Patent Publication Number: US-11048744-B1

Title: Computer architecture for weighting search results by stylistic preferences

Description:
TECHNICAL FIELD 
     The present disclosure generally relates to a computer architecture for a database of files, and more specifically relates to identifying and weighting files in the database responsive to a search query. 
     BACKGROUND 
     Network accessible data file repositories for content commonly hosted on server devices ordinarily provide users of client devices with an ability to access search algorithms for searching and accessing data files for content in the data file repositories. For example, for a network accessible media content repository with a large volume of data files, such as for images and videos, a user that seeks to search for media related to cats may enter the search query “cats” into a search interface for the online image content repository accessible by and displayed on the user&#39;s client device. Media associated with the keyword “cat” or “cats” that is determined by the server to be responsive to the search query may then be returned to the client device for display to the user. 
     Searching for content, such as images, can present challenges to the user because it can often be difficult to express in text what the user is looking for—particularly the user&#39;s stylistic preferences. For example, if a user is looking for an image of an elderly couple photographed in a certain style, most image retrieval systems for data file repositories are limited to supporting textual keyword searches. In this case, the user submits a search query for “elderly couple,” and then browses through many images from the data file repository provided in response to the search query that do not match the user&#39;s stylistic interests until the user identifies at least one or two images that do match those stylistic preferences. 
     The description provided in the background section should not be assumed to be prior art merely because it is mentioned in or associated with the background section. The background section may include information that describes one or more aspects of the subject technology. 
     SUMMARY 
     The disclosed system provides for building a style profile for a user based on images the user has previously indicated a preference for, and using that style profile to improve search results for images responsive to the user&#39;s search query. The image search results can then be sorted, categorized, or filtered based on one or many of the user&#39;s style profiles. 
     According to certain aspects of the present disclosure, a computer-implemented method for identifying data files responsive to a search query and weighted according to a stylistic preference is provided. The method includes receiving a search query for a collection of media files from a device associated with a user, the user associated with a user identifier, and identifying a set of image files from the collection of media files that is responsive to the search query, wherein each image file in the set of image files is associated with a relevancy score indicating a relevance of the respective image file to the search query. The method also includes retrieving a stylistic preference profile associated with the user identifier to apply to the set of image files, and weighting the relevancy score for each image file in the set of image files according to the stylistic preference profile associated with the user identifier to generate a weighted stylistic preference score for each image file in the set of image files. The method further includes creating a listing of the set of image files that is sorted according to the weighted stylistic preference score of each respective image file in the set of image files, and providing the listing to the device associated with the user for display. 
     According to certain aspects of the present disclosure, a system for identifying data files responsive to a search query and weighted according to a stylistic preference is provided. The system includes a memory that includes instructions, and a processor. The processor is configured to execute instructions which, when executed, cause the processor to identify a subset of image files, from a collection of media files, with which a user has previously interacted, and cluster the subset of image files into a number of clusters based on their stylistic similarity. The stylistic similarity of each image file in the subset of image files is determined using an image vector corresponding to each image file. Each image file in the collection of media files has an associated unique index value mapping each image file to a corresponding dense image vector for the image file capturing a visual nature of the image file. Each image file in the subset of image files is associated with a stylistic centroid of one of the clusters. The processor is also caused to assign a user profile cluster weight value for the user to each cluster based on a normalized count of images in the cluster, receive a search query for the collection of media files from a device associated with the user, the user associated with a user identifier, and identify a set of image files from the collection of media files that is responsive to the search query, wherein each image file in the set of image files is associated with a relevance score indicating a relevance of the respective image file to the search query. The processor is also caused to retrieve a stylistic preference profile associated with the user identifier to apply to the set of image files which includes the user profile cluster weight values and information regarding the clusters, and weight the relevancy score for each image file in the set of image files according to the stylistic preference profile associated with the user identifier to generate a weighted stylistic preference score for each image file in the set of image files. The processor is further caused to create a listing of the set of image files that is sorted according to the weighted stylistic preference score of each respective image file in the set of image files, and provide the listing to the device associated with the user for display. 
     According to certain aspects of the present disclosure, a non-transitory machine-readable storage medium includes machine-readable instructions for causing a processor to execute a method is provided. The method includes receiving a search query for a collection of media files from a device associated with a user, the user associated with a user identifier, and identifying a set of image files from the collection of media files that is responsive to the search query, wherein each image file in the set of image files is associated with a relevancy score indicating a relevance of the respective image file to the search query. The method also includes retrieving a stylistic preference profile associated with the user identifier to apply to the set of image files, and weighting the relevancy score for each image file in the set of image files according to the stylistic preference profile associated with the user identifier to generate a weighted stylistic preference score for each image file in the set of image files. The method further includes creating a listing of the set of image files that is sorted according to the weighted stylistic preference score of each respective image file in the set of image files, and providing the listing to the device associated with the user for display. 
     According to certain aspects of the present disclosure, a system for identifying data files responsive to a search query and weighted according to a stylistic preference is provided. The system includes means for storing instructions and means for executing the instructions. The means for executing the instructions is configured to identify a subset of image files, from a collection of media files, with which a user has previously interacted, and cluster the subset of image files into a number of clusters based on their stylistic similarity. The stylistic similarity of each image file in the subset of image files is determined using an image vector corresponding to each image file. Each image file in the collection of media files has an associated unique index value mapping each image file to a corresponding dense image vector for the image file capturing a visual nature of the image file. Each image file in the subset of image files is associated with a stylistic centroid of one of the clusters. The means for executing the instructions is also configured to assign a user profile cluster weight value for the user to each cluster based on a normalized count of images in the cluster, receive a search query for the collection of media files from a device associated with the user, the user associated with a user identifier, and identify a set of image files from the collection of media files that is responsive to the search query; wherein, each image file in the set of image files is associated with a relevance score indicating a relevance of the respective image file to the search query. The means for executing the instructions is further configured to retrieve a stylistic preference profile associated with the user identifier to apply to the set of image files, which includes the user profile cluster weight values and information regarding the clusters, and weight the relevancy score for each image file in the set of image files according to the stylistic preference profile associated with the user identifier to generate a weighted stylistic preference score for each image file in the set of image files. The means for executing the instructions is yet further configured to create a listing of the set of image files that is sorted according to the weighted stylistic preference score of each respective image file in the set of image files, and provide the listing to the device associated with the user for display. 
     According to certain aspects of the present disclosure, a computer-implemented method for identifying data files responsive to a search query and weighted according to a stylistic preference is provided. The method includes providing a search query for a collection of media files from a device associated with a user to a server, the user associated with a user identifier, and receiving, from the server and for display on the device, a listing of a set of image files that is responsive to the search query and that is sorted according to a weighted stylistic preference score of each respective image file in the set of image files generated based on a stylistic preference profile associated with the user identifier. The provided listing of the set of image files is grouped according to a stylistic similarity cluster to which the respective image file belongs. 
     It is understood that other configurations of the subject technology will become readily apparent to those skilled in the art from the following detailed description, wherein various configurations of the subject technology are shown and described by way of illustration. As will be realized, the subject technology is capable of other and different configurations and its several details are capable of modification in various other respects, all without departing from the scope of the subject technology. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide further understanding and are incorporated in and constitute a part of this specification, illustrate disclosed embodiments and together with the description serve to explain the principles of the disclosed embodiments. In the drawings: 
         FIG. 1  illustrates an example architecture for identifying data files responsive to a search query and weighted according to a stylistic preference. 
         FIG. 2  is a block diagram illustrating the example client and server from the architecture of  FIG. 1  according to certain aspects of the disclosure. 
         FIG. 3A  illustrates an example process for pre-processing data files to weight them according to a user&#39;s stylistic preference using the example server of  FIG. 2 . 
         FIG. 3B  illustrates an example process for identifying data files responsive to a search query and weighted according to a user&#39;s stylistic preference. 
         FIGS. 4A-4F  are example illustrations associated with the example processes of  FIGS. 3A and 3B . 
         FIG. 5  is a block diagram illustrating an example computer system with which the client and server of  FIG. 2  can be implemented. 
     
    
    
     In one or more implementations, not all of the depicted components in each figure may be required, and one or more implementations may include additional components not shown in a figure. Variations in the arrangement and type of the components may be made without departing from the scope of the subject disclosure. Additional components, different components, or fewer components may be utilized within the scope of the subject disclosure. 
     DETAILED DESCRIPTION 
     The detailed description set forth below is intended as a description of various implementations and is not intended to represent the only implementations in which the subject technology may be practiced. As those skilled in the art would realize, the described implementations may be modified in various different ways, all without departing from the scope of the present disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. 
     General Overview 
     The disclosed system provides for generating one or several profiles of stylistic preferences of a user for image files using, for example, past interaction data for the user with image files or asking the user to provide stylistic preference data (and thereafter saving the stylistic preferences as a stylistic preference profile for the user). Thereafter, when a user submits a search query for image files from a collection of images, the image files that are responsive to the search query and the user&#39;s selected stylistic preference profile can be returned. The responsive image files can be, for example, ranked according to their relevance and/or a stylistic preference profile score, grouped by stylistic profile, and/or filtered by stylistic profile. 
     The disclosed system provides an improvement to computer functionality by allowing computer performance of a function not previously performed by a computer. Specifically, the disclosed system provides for an identification, using user-specific weighted stylistic preference scores, of image files that are responsive both to a user&#39;s search query and a stylistic preference profile of the user. 
     The ability to separately extract both a stylistic representation and a content representation from an image file can be used to help power an image search engine informed by stylistic preferences as disclosed herein. In this regard, the disclosed system can take a set of image files and group them based on a notion of distance in their stylistic representation alone. If operating over a set of image files known to interest a particular user, the disclosed system can generate a compact representation of the user&#39;s stylistic preferences. This representation is used to alter a standard set of search results, essentially boosting all images that are also stylistically similar to the user&#39;s past stylistic preferences. The ability to compare any pair of images in a style space also enables a novel way of grouping a set of images, e.g. search results, by style, irrespective of a user&#39;s preferences. This allows for a new user who has not yet expressed any style preferences to the system to quickly browse a set of search results grouped by style, where, for example, every row of results contains images in a particular style. It is also shown that the stylistic “cold-start problem” can be addressed by presenting a user with a series of image pairs and allowing the user to indicate which images the user stylistically prefers. 
     Although certain examples provided herein may describe a user&#39;s information (e.g., a user&#39;s interaction data with image files) being stored in memory, in certain aspects each user must grant explicit permission for such user information to be stored. The explicit permission may be granted using privacy controls integrated into the disclosed system. If requested user information includes demographic information, then the demographic information is aggregated on a group basis and not by individual user. Each user is provided notice that such user information will be stored with such explicit consent, and each user may at any time end having the user information stored, and may delete the stored user information. The stored user information may be encrypted to protect user security. 
     The user can at any time delete the user information from memory and/or opt out of having the user information stored in memory. Additionally, the user can, at any time, adjust appropriate privacy settings to selectively limit the types of user information stored in memory, or select the memory in which the user information is stored (e.g., locally on the user&#39;s device as opposed to remotely a server). In many examples, the user information does not include and/or share the specific identification of the user (e.g., the user&#39;s name) unless otherwise specifically provided or directed by the user. 
     Example System Architecture 
       FIG. 1  illustrates an example architecture  100  for identifying data files responsive to a search query and weighted according to a stylistic preference. The architecture  100  includes servers  130  and clients  110  connected over a network  150 . 
     One of the many servers  130  is configured to host a search engine, a collection of media files, a user profile database, and a convolutional neural network. For purposes of load balancing, multiple servers  130  can host the search engine, collection of media files, and the convolutional neural network. The servers  130  can be any device having an appropriate processor, memory, and communications capability for hosting the search engine, collection of media files, user profile database, and convolutional neural network. In certain aspects, one or more of the servers  110  can be a cloud computing server of an infrastructure-as-a-service (IaaS) and be able to support a platform-as-a-service (PaaS) and software-as-a-service (SaaS) services. 
     As discussed herein, the search engine is configured to receive a search query associated with a user identifier (e.g., from one of the clients  110  over the network  150 ), and search the collection of media files to identify image files that are responsive to the search query. The identification of the image files can be facilitated by use of an index of data vectors for the image files in the collection of media files that is generated using the convolutional neural network. In certain aspects, media files (and their corresponding data vectors) may be provided over the network  150  from other devices, such as devices owned by users that generate the media files for consumption. 
     The clients  110  can be, for example, desktop computers, mobile computers, tablet computers (e.g., including e-book readers), mobile devices (e.g., a smartphone or PDA), set top boxes (e.g., for a television), video game consoles, or any other devices having appropriate processor, memory, and communications capabilities. The network  150  can include, for example, any one or more of a personal area network (PAN), a local-area network (LAN), a campus area network (CAN), a metropolitan area network (MAN), a wide-area network (WAN), a broadband network (BBN), the Internet, and the like. Further, the network  150  can include, but is not limited to, any one or more of the following network topologies, including a bus network, a star network, a ring network, a mesh network, a star-bus network, tree or hierarchical network, and the like. 
     The search engine is configured to assign a relevancy score to each identified image file. The relevancy score can be based on, for example, a distance of a data vector associated with an image file from a centroid of a cluster associated with a parameter of the received search query. The search engine is also configured to retrieve a stylistic preference profile associated with the user identifier from the user profile database. Alternatively, if the user identifier is associated with more than one stylistic preference profile, the search engine can retrieve several stylistic preference profiles associated with the user identifier (e.g., a particular stylistic preference profile associated with a user identifier can be received along with the search query). The search engine is configured to weight the relevancy score assigned to each identified image file according to the stylistic preference profile associated with the user identifier in order to generate a weighted stylistic preference score for each image file. The identified image files (as responsive to the user&#39;s search query) are then returned by the search engine on one of the servers  130  either ranked, categorized, and/or filtered by weighted stylistic preference score or stylistic preference profile back to the client  110  from which the search query was received. 
     Example User Stylistic Preference Profile Weighting System for Image Files 
       FIG. 2  is a block diagram illustrating an example server  130  and client  110  in the architecture  100  of  FIG. 1  according to certain aspects of the disclosure. 
     The client  110  and the server  130  are connected over the network  150  via respective communications modules  218  and  238 . The communications modules  218  and  238  are configured to interface with the network  150  to send and receive information, such as data, requests, responses, and commands to other devices on the network. The communications modules  218 ,  258 , and  238  can be, for example, modems or Ethernet cards. 
     The server  130  includes a processor  236 , a communications module  238 , and a memory  232  that includes a search engine  242 , a collection of media files  244 , a convolutional neural network  234 , and a user profile database  240 . 
     The search engine  242  is configured to receive a search query (e.g., from an application  222  running in a memory  220  of the client  110  over the network  150 ), and search the collection of media files for media files that are responsive to the search query based on identifiers associated with the media files that match or otherwise have a sufficient degree of similarity to parameters (e.g., terms) of the search query. The search query can include search parameters (e.g., keywords) entered by the user of the client  110  using an input device  216  of the client  110  and processed by a processor  212  of the client  110  prior to being sent by the application  222  (e.g., a web browser) on the client  110  over the network  150  to the search engine  242  on the server  130 . 
     The search engine  242 , upon receipt of the search query from the client  110 , may access an index of identifiers that is accessible for the collection of media files  244  in order to more quickly identify media files responsive to the search query. Once media files are identified as responsive to a received search query, the search engine is configured to return a listing (e.g., a copy of a web page) with identifiers (e.g., links to thumbnails) of the media files responsive to the received search query. In certain aspects, each of the media files responsive to the received search query, such as image files, are associated with a relevance score indicating a relevance of the respective image file to the search query. 
     The collection of media files  240  includes files such as images, video recordings with or without audio, visual multimedia (e.g., slideshows). In certain aspects the collection of media files  240  also includes a dense vector for each media file in the collection of media files  240 , and each media file in the collection of media files  240  is mapped to its corresponding dense vector representation using a unique index value for the media file that is listed in an index. The dense vector representation of a media file (e.g., a 256 dimensional vector) captures the visual nature of the corresponding media file (e.g., of a corresponding image). The dense vector representation of a media file is such that, for example, given a pair of dense vector representations for a corresponding pair of images, similarity calculations, such as by using a cosine similarity algorithm, can meaningfully capture a stylistic similarity between the images. In certain aspects, each dense image vector can be normalized (e.g., to be the same scale) prior to later processing, e.g., prior to applying the cosine similarity algorithm to each dense image vector in order to expedite such later processing. 
     The convolutional neural network  234  can be a type of feed-forward artificial neural network where individual neurons are tiled in such a way that the individual neurons respond to overlapping regions in a visual field. The architecture of the convolutional neural network  234  may be in the style of existing well-known image classification architectures such as AlexNet, GoogLeNet, or Visual Geometry Group (VGG) models. In certain aspects, the convolutional neural network  234  consists of a stack of convolutional layers followed by several fully connected layers. The convolutional neural network  234  can include a loss layer (e.g., softmax or hinge loss layer) to back propagate errors so that the convolutional neural network  234  learns and adjusts its weights to better fit provided image data. The convolutional neural network  234  can be used to train a model to generate the dense vector representations for media files, such as for images, and map each media file to its corresponding dense vector representation in a dense vector space, wherein distance can be calculated between points associated with the dense vector representations in the dense vector space. 
     The user profile database  240  includes user identifiers and stylistic preference information for the user identifiers. For example, for a particular user identifier, the user profile database  240  can store one or several user stylistic preference profiles associated with that particular user identifier, past browsing behavior (e.g., user selections or downloads of particular image files) associated with that particular user identifier, responses to stylistic preference prompts associated with training images from the collection of media files  244 , and predicted image files the user is likely to stylistically prefer based on past browsing behavior of the user. The user profile database  240  can further store, for example, an identification of image files from the collection of media files  244  with which the user has interacted or is likely to stylistically prefer, a cluster mapping of these identified images, described in further detail below, and weight values associated with the clusters, also described in further detail below. 
     Data vectors for each of the media files from the collection of media files  244  can be clustered by the processor  236  into a predetermined number of clusters according to a clustering algorithm, such as agglomerative clustering. As noted above, information on the clustering as described herein can be stored by the user profile database  240 . 
     Agglomerative clustering may be performed using Ward or average linkage over a set of image files indicated as preferred by the user using the stylistic loss between each image file pair as the affinity measure. For example, the data vectors for the media files from the collection of the media files  244  can be assigned to clusters by the clustering algorithm based on a similarity threshold. The tree of clusters may be cut when K clusters remain, and the existing clusters can be treated as representing stylistically cohesive groups. In other words, the number of clusters can be manually selected (e.g., as a predetermined number of clusters), such as, for example, designating that the collection of the media files be divided into 1000 clusters. 
     Alternatively, the number of clusters can be decided using a threshold linkage score. The thresholded linkage score can be used as a stopping criteria for the agglomerative clustering algorithm. For instance, clusters may be combined until the average linkage value is more than a universal threshold determined to ensure clusters retain some minimal stylistic cohesiveness. In certain aspects, the universal threshold can be determined by manually examining a large number of user-defined threshold values and evaluating the results of clusterings for a large set of examples based on those user-defined threshold values to determine the largest value that stylistically maintains cohesive clusters. In certain aspects, the universal threshold can be determined by tuning the universal threshold value via A-B testing where different values are used for different segments of users and the value that produces the best user satisfaction is chosen, with metrics such as engagement or total downloaded images used as proxies of user satisfaction. 
     Data vectors for the media files from the collection  244  can also be designated to belong to one of the clusters based on a similarity threshold using a clustering algorithm. The similarity threshold can indicate stylistic similarity, visual similarity, conceptual similarity, keyword similarity, or another measurement of similarity between media files. Other clustering algorithms can also be used, including other methods of vector quantization, or other clustering approaches such as affinity propagation clustering, agglomerative clustering, Birch clustering, density-based spatial clustering of applications with noise (DBSCAN), feature agglomeration, mini-batch k means clustering, mean shift clustering using a flat kernel, or spectral clustering. The clustering may occur prior to a user submitting a search query, but subsequent to the user indicating that user is available to submit the search query (e.g., after a web page including a search interface for the search engine  242  is requested from the server  130  by the application  222  on the client  110  of the user. 
     Subsequent to completion of clustering of the image files, a centroid is computed for each cluster. The centroid, which is used to represent the cluster, may be considered a stylistic average of the image files of the centroid. In certain aspects, the centroid for a cluster is computed as the image file in the cluster that has the lowest average distance to all other image files in the cluster. 
     In certain aspects, weighting the relevancy score for each image file (e.g., for which the user has indicated a preference such as based on past interaction) to generate the weighted stylistic preference score occurs in a process of first, for each image file in the set of image files, setting a style boost score as zero. Next, for each cluster, the process includes computing a distance between each image file in the set of image files (e.g., by calculating the stylistic loss between the two image files) and the stylistic centroid of the respective cluster. 
     The distance can be computed according to various approaches. For example, in certain aspects, the disclosed system builds on the stylistic loss function between a pair of image files that captures the degree to which two images differ stylistically, as disclosed by Gatys et al in “Style Transfer Using Convolutional Neural Networks,” which builds upon the Visual Geometry Group (VGG) convolutional neural network  234  and its feature space defined in K. Simonyan et al&#39;s “Very Deep Convolutional Networks for Large-Scale Image Recognition” (2015), for which the feature space of the VGG network is built on top of “Texture Synthesis Using Convolutional Neural Networks” by Gatys et al (2015), each of which are incorporated by reference herein in its entirety for all purposes. 
     In the disclosed system, the processor  236  of the server  130  is configured to obtain a representation of a style of an input image using a feature space designed to capture texture information. In certain aspects, the feature space is built on top of filter responses in any layer of the VGG network. The feature space consists of correlations between different filter responses, where expectation is taken over a spatial extent of feature maps. These feature correlations are given by the Gram matrix G l ϵR N     l     ×N     l   , where G l   ij  is the inner product between the vectorized feature maps i and j in layer l: 
     
       
         
           
             
               
                 
                   
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     There are multiple Gram matrices, one at each layer of the convolutional neural network  234 , which correspond to a multi-scale representation of the image designed to capture texture information representative of style but not content. In other words, each image file from the collection of media files  244  can be associated with a Gram matrix when processed by the convolutional neural network  234 . 
     For example, for a given pair of image files from the collection of media files  244 , the processor  236  is configured to compute the Gram matrices for each image file separately. For each layer in the convolutional neural network  234 , the processor  236  is configured to then compute the contribution to a total loss function using equation (2) below, where G l   ij  is the i,jth entry in the lth layer Gram matrix for the one of the image files and A l   ij  is the corresponding entry for the Gram matrices A for the second image file: 
     
       
         
           
             
               
                 
                   
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     Equation (3) represents a total loss across all layers in the network, where a weight factor indicates how important each layer is to the total loss: 
     
       
         
           
             
               
                 
                   
                     
                       
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     The disclosed configuration allows for taking any pair of image files, pass each image through the convolutional neural network  234 , obtain filter responses for each layer in the network, generate Gram matrices from these filter responses, and then calculate a loss function which indicates a distance in style space between any pair of image files. 
     After computing the distance in style space, the process for weighting the relevancy score for each image file to generate the weighted stylistic preference score includes updating the style boost score for a respective image file as a sum of the current style boost score for the image file and the user profile cluster weight value for the respective cluster, divided by a sum of a threshold value plus the computed distance between the respective image file and the stylistic centroid of the respective cluster. 
     The user profile cluster weight value for a cluster can be based on a normalization of the count of image files in each cluster by the total number of image files that have been clustered. For example, if there are 5, 10, and 15 image files in clusters 1, 2, and 3, respectively, then because there are a total of 30 image files, the user profile cluster weight value for clusters 1, 2, and 3 are 5/30, 10/30, and 15/30, or [0.17, 0.33, 0.5]. 
     When no clusters remain, the weighted stylistic preference score is calculated for a respective image file as the updated style boost score for the respective image file multiplied by the relevancy score for the respective image file. The process then proceeds to iterate through each of the clusters for the next image file in the set of image files, until no image files remain in the set of image files to process. 
     In certain aspects, the user profile database  240  includes pre-processed stylistic preference information (e.g., processed before receiving a search query) for users. For example, in certain aspects, the processor  236  of the server  130  is configured to identify a subset of image files, from the collection of media files  244 , with which a user (based on a user identifier associated with the user) has previously interacted. The subset of image files can include, for example, image files that are predicted to be preferred by the user based on past browsing behavior of the user, or the subset of image files can include a predetermined number of images previously downloaded by or selected by the user. The subset of image files can also include image files previously presented to the user in subgroups with other image files, where the user has indicated their preference for the respective image file among the subgroups with the other image files. For example, if a user is presented with two image files and asked which image file the user prefers, and the user indicates a first of the two image files, then the first of the two image files is included in the subset of image files indicated as preferred by the user. In certain aspects, an image selection bias may be corrected for, for example, where a user might prefer an image of a person smiling over a person frowning regardless of a stylistic preference of the user. 
     The processor  236  is configured to cluster this subset of image files into a number of clusters based on their stylistic similarity. The stylistic similarity of each image file in the subset of image files is determined using an image vector corresponding to each image file. Each image file in the subset of image files is associated with a stylistic centroid of one of the clusters. The processor  236  is further configured to assign a user profile cluster weight value for the user to each cluster based on a normalized count of images in the cluster. The user profile cluster weight values and information regarding the clusters in the stylistic preference profile associated with the user identifier are stored in the user profile database  240 . 
     The processor  236  of the server  130  is configured to execute instructions, such as instructions physically coded into the processor  236 , instructions received from software in memory  240  (e.g., search engine  242 ), or a combination of both. For example, the processor  236  of the server  130  executes instructions to receive a search query for the collection of media files  244  from the client  110  that is associated with a user, the user being associated with a user identifier, and identify a set of image files from the collection of media files  244  that is responsive to the search query. Each image file in the set of image files is associated (e.g., by the processor  236  by instructions from the search engine  242 ) with a relevancy score indicating a relevance of the respective image file to the search query. The processor  236  is also configured to retrieve a stylistic preference profile associated with the user identifier (e.g., from the user profile database  240 ) to apply to the set of image files, and weight the relevancy score for each image file in the set of image files according to the stylistic preference profile associated with the user identifier to generate a weighted stylistic preference score for each image file as described above. The processor  236  is further configured to create a listing of the set of image files that is sorted according to the weighted stylistic preference score of each respective image file in the set of image files, and provide the listing to the client  110  (e.g., as a web page for display in the application  222 ) associated with the user for display (e.g., on an output device  214 ) of the client  110 . 
     In certain aspects, when the listing is provided to the client  110  associated with the user for display, the provided listing of the set of image files is grouped according to the associated cluster to which the respective image file belongs. For example, a copy of web page with a user interface displaying the provided listing of the set of image files in response to the search query can be provided by the server  130  to the application  222  on the client  110  for display in the application  222 . In certain aspects, the listing is filterable by the associated cluster to which the respective image file belongs. For example, if listings each associated with a different cluster representative of a stylistic preference of the user are displayed, then the user can select or de-select in the user interface a label associated with a respective stylistic preference in order to display or remove from display in the user interface the image files associated with the stylistic preference. In certain aspects, the label can be named or renamed by the user. For example, if the label is simply titled “Style  1 ,” but the user views the stylistic preference associated with the style as representative of tilt-shift photography, then the label can be relabeled in the user interface by the user from “Style  1 ” to “Tilt-Shift.” 
     The techniques described herein may be implemented as method(s) that are performed by physical computing device(s); as one or more non-transitory computer-readable storage media storing instructions which, when executed by computing device(s), cause performance of the method(s); or, as physical computing device(s) that are specially configured with a combination of hardware and software that causes performance of the method(s). 
       FIG. 3A  illustrates an example process  300  for pre-processing data files to weight them according to a user&#39;s stylistic preference using the example client  110  of  FIG. 2 . While  FIG. 3  is described with reference to  FIG. 2 , it should be noted that the process steps of  FIG. 3  may be performed by other systems. 
     The process  300  begins by proceeding from beginning step  301  when a request for pre-processing of image files is received to step  302  a subset of image files, from the collection of media files  244 , with which a user has previously interacted is identified. As noted above, each image file in the collection of media files  244  has an associated unique index value mapping each image file to a corresponding dense image vector for the image file capturing a visual nature of the image file. For example, with reference to the example illustration  400  of  FIG. 4A , the user may previously have presented with a survey of image files, presented in pairs, prompting the user to identify a stylistic preference of the user for one image file  401  as compared to the other image file  402 . The stylistic preference of the user can be indicated as a binary preference (i.e., the user prefers one image file over another image file without reference to a degree of preference), or as a degree of preference that can be indicated by a user on a scale  403 . In the example illustration  400 , the user indicates a stylistic preference for images of women with arms crossed. Surveying the user with such subgroups of image files can facilitate identifying a stylistic preference of the user where no previous stylistic preference data for the user exists in the user profile database  240 . The stylistic preference of the user for a particular image file, and the degree of that preference, may then be stored for the user according to the user&#39;s identifier in the user profile database  240 . An inference can then be made from the user&#39;s indicated stylistic preference as to other image files from the collection of media files  244  that the user would likely prefer stylistically. The user can then confirm  413  the inference by way of a second user interface presenting the other image files  411  and  412  from the collection of media files  244  as provided in the example illustration  410  of  FIG. 4B . 
     Next, in step  303 , the subset of image files is clustered into a number of clusters based on their stylistic similarity using one of the clustering approaches disclosed herein, wherein the stylistic similarity of each image file in the subset of image files is determined using an image vector corresponding to each image file, and wherein each image file in the subset of image files is associated with a stylistic centroid of one of the clusters. Finally, in step  304 , a user profile cluster weight value for the user is assigned to each cluster based on a normalized count of images in the cluster, as described above. The process  300  ends in step  305 . 
       FIG. 3B  illustrates an example process  350  for identifying data files responsive to a search query and weighted according to a user&#39;s stylistic preference. The process  350  begins by proceeding from beginning step  351 , for example, when a user indicates an interest in submitting a search query for the collection of media files  244  to the search engine  242 , such as by the application  222  on the client  110  of the user requesting a copy of a web page with an interface to submit a search query to the search engine  242  from the server, to step  352  when the search query for the collection of media files  244  is received from the client  110  associated with the user, where the user associated with a user identifier. In certain aspects, the user identifier may be provided by the application  222  along with the search query submitted by the user.  FIG. 4C  provides an example illustration  420  of a copy of the web page displayed by the application  222  (e.g., a web browser) on the client  110  with a user seeking to submit a search query of the term “woman”  422  in a search input field  421  for the search engine  421 . 
     Next, in step  353 , a set of image files from the collection of media files  244  is identified that is responsive to the search query. As noted above, each image file in the set of image files is associated with a relevance score (e.g., by the search engine  242 ) indicating a relevance of the respective image file to the search query.  FIG. 4D  provides an example illustration  430  of a set of image files as search results  431  responsive to the search query “woman”  422  (in the input field  421 ) and ranked by relevance score that would be displayed in the application  222  prior to analysis of the user&#39;s stylistic preference. Included in the set of image files are three images  432 ,  433 , and  434  of women with their arms crossed. 
     In step  354  a stylistic preference profile associated with the user identifier (associated with the client  110  or received with the search query) is retrieved (e.g., from the user profile database  240 ) to apply to the set of image files (identified as responsive to the search query). The stylistic preference profile includes the user profile cluster weight values for the image files in the set, and information regarding the clusters with which the image files in the set are associated. 
     Subsequently, in beginning loop step  355 , a loop begins for each image file in the set of image files, in which at first in step  356  a style boost score is set as zero for the current image file from the set for which the loop is being performed. 
     Next, in subloop beginning step  357 , a subloop begins for each cluster among all of the clusters, in which at first in step  358  a distance is computed between each image file in the set of image files and the stylistic centroid of the respective cluster for which the subloop is being performed. Next, in subloop step  359 , the style boost score for the respective image file of the loop is updated as a sum of the current style boost score for the image file of the loop and the weight value for the respective cluster of the subloop, divided by a sum of a threshold value plus the computed distance between the respective image file of the loop and the stylistic centroid of the respective cluster of the subloop. 
     If another cluster remains at end subloop step  360 , the process  350  returns to beginning subloop step  357 , otherwise the process  350  proceeds to end loop step  361 . 
     If another image file remains in the set of image files at end loop step  361 , the process  350  returns to beginning loop step  355 , otherwise the process  350  proceeds to step  362 . 
     In step  362 , the weighted stylistic preference score for the respective image file is calculated as the updated style boost score for the respective image file multiplied by the relevancy score for the respective image file. In step  363 , a listing of the set of image files is created that is sorted according to the weighted stylistic preference score of each respective image file in the set of image files. In step  364  the listing is provided (e.g., over the network  150 ) as search results  441  for the search query  422  (e.g., in the search input field  421 ) to the client  110  associated with the user for display (e.g., through the output device  214  via the application  222 ), as provided in the example illustration  440  of  FIG. 4E . In the example illustration  440 , the three images that would have been provided as search results  432 ,  433 , and  434  without reference to a stylistic preference of the user (as illustrated in  FIG. 4D ) now appear earlier in the sort, and the search results  441  include many more images of women with their arms crossed, which is indicative of the stylistic preference of the user submitting the search as noted earlier for the user with reference to  FIG. 4A . 
     Additionally, in certain aspects and as provided in the example illustration  450  of  FIG. 4F , search results for the “woman” search query  422  in the input field  421  can be grouped according to stylistic preference, with a first group of image files  453  grouped according to a first stylistic preference of the user, “Style  1 ”  451  (e.g., with images of women with their arms crossed), and a second group of image files  454  grouped according to a second stylistic preference of the user, “Style  2 ”  452  (e.g., with images of women with a bright light source and in nature). For each group of image files  453  and  454 , the image files that are displayed may be sorted according to the highest weighted stylistic preference score for the style of the group (e.g., image files sorted by lowest distance to the centroid for the style). The process  350  ends in step  365 . 
     Hardware Overview 
       FIG. 5  is a block diagram illustrating an example computer system  500  with which the client  110  and server  130  of  FIG. 2  can be implemented. In certain aspects, the computer system  500  may be implemented using hardware or a combination of software and hardware, either in a dedicated server, or integrated into another entity, or distributed across multiple entities. 
     Computer system  500  (e.g., client  110  and server  130 ) includes a bus  508  or other communication mechanism for communicating information, and a processor  502  (e.g., processor  212  and  236 ) coupled with bus  508  for processing information. According to one aspect, the computer system  500  can be a cloud computing server of an IaaS that is able to support PaaS and SaaS services. According to one aspect, the computer system  500  is implemented as one or more special-purpose computing devices. The special-purpose computing device may be hard-wired to perform the disclosed techniques, or may include digital electronic devices such as one or more application-specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs) that are persistently programmed to perform the techniques, or may include one or more general purpose hardware processors programmed to perform the techniques pursuant to program instructions in firmware, memory, other storage, or a combination. Such special-purpose computing devices may also combine custom hard-wired logic, ASICs, or FPGAs with custom programming to accomplish the techniques. The special-purpose computing devices may be desktop computer systems, portable computer systems, handheld devices, networking devices or any other device that incorporates hard-wired and/or program logic to implement the techniques. By way of example, the computer system  500  may be implemented with one or more processors  502 . Processor  502  may be a general-purpose microprocessor, a microcontroller, a Digital Signal Processor (DSP), an ASIC, a FPGA, a Programmable Logic Device (PLD), a controller, a state machine, gated logic, discrete hardware components, or any other suitable entity that can perform calculations or other manipulations of information. 
     Computer system  500  can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them stored in an included memory  504  (e.g., memory  220  and  234 ), such as a Random Access Memory (RAM), a flash memory, a Read Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Erasable PROM (EPROM), registers, a hard disk, a removable disk, a CD-ROM, a DVD, or any other suitable storage device, coupled to bus  508  for storing information and instructions to be executed by processor  502 . The processor  502  and the memory  504  can be supplemented by, or incorporated in, special-purpose logic circuitry. Expansion memory may also be provided and connected to computer system  500  through input/output module  510 , which may include, for example, a SIMM (Single In Line Memory Module) card interface. Such expansion memory may provide extra storage space for computer system  500 , or may also store applications or other information for computer system  500 . Specifically, expansion memory may include instructions to carry out or supplement the processes described above, and may include secure information also. Thus, for example, expansion memory may be provided as a security module for computer system  500 , and may be programmed with instructions that permit secure use of computer system  500 . In addition, secure applications may be provided via the SIMM cards, along with additional information, such as placing identifying information on the SIMM card in a non-hackable manner. 
     The instructions may be stored in the memory  504  and implemented in one or more computer program products, e.g., one or more modules of computer program instructions encoded on a computer-readable medium for execution by, or to control the operation of, the computer system  500 , and according to any method well known to those of skill in the art, including, but not limited to, computer languages such as data-oriented languages (e.g., SQL, dBase), system languages (e.g., C, Objective-C, C++, Assembly), architectural languages (e.g., Java, .NET), and application languages (e.g., PHP, Ruby, Perl, Python). Instructions may also be implemented in computer languages such as array languages, aspect-oriented languages, assembly languages, authoring languages, command line interface languages, compiled languages, concurrent languages, curly-bracket languages, dataflow languages, data-structured languages, declarative languages, esoteric languages, extension languages, fourth-generation languages, functional languages, interactive mode languages, interpreted languages, iterative languages, list-based languages, little languages, logic-based languages, machine languages, macro languages, metaprogramming languages, multiparadigm languages, numerical analysis, non-English-based languages, object-oriented class-based languages, object-oriented prototype-based languages, off-side rule languages, procedural languages, reflective languages, rule-based languages, scripting languages, stack-based languages, synchronous languages, syntax handling languages, visual languages, wirth languages, embeddable languages, and xml-based languages. Memory  504  may also be used for storing temporary variable or other intermediate information during execution of instructions to be executed by processor  502 . 
     A computer program as discussed herein does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, subprograms, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network, such as in a cloud-computing environment. The processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. 
     Computer system  500  further includes a data storage device  506  such as a magnetic disk or optical disk, coupled to bus  508  for storing information and instructions. Computer system  500  may be coupled via input/output module  510  to various devices. The input/output module  510  can be any input/output module. Example input/output modules  510  include data ports such as USB ports. In addition, input/output module  510  may be provided in communication with processor  502 , so as to enable near area communication of computer system  500  with other devices. The input/output module  510  may provide, for example, for wired communication in some implementations, or for wireless communication in other implementations, and multiple interfaces may also be used. The input/output module  510  is configured to connect to a communications module  512 . Example communications modules  512  (e.g., communications module  218  and  238 ) include networking interface cards, such as Ethernet cards and modems. 
     The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. The communication network (e.g., network  150 ) can include, for example, any one or more of a PAN, a LAN, a CAN, a MAN, a WAN, a BBN, the Internet, and the like. Further, the communication network can include, but is not limited to, for example, any one or more of the following network topologies, including a bus network, a star network, a ring network, a mesh network, a star-bus network, tree or hierarchical network, or the like. The communications modules can be, for example, modems or Ethernet cards. 
     For example, in certain aspects, communications module  512  can provide a two-way data communication coupling to a network link that is connected to a local network. Wireless links and wireless communication may also be implemented. Wireless communication may be provided under various modes or protocols, such as GSM (Global System for Mobile Communications), Short Message Service (SMS), Enhanced Messaging Service (EMS), or Multimedia Messaging Service (MMS) messaging, CDMA (Code Division Multiple Access), Time division multiple access (TDMA), Personal Digital Cellular (PDC), Wideband CDMA, General Packet Radio Service (GPRS), or LTE (Long-Term Evolution), among others. Such communication may occur, for example, through a radio-frequency transceiver. In addition, short-range communication may occur, such as using a BLUETOOTH, WI-FI, or other such transceiver. 
     In any such implementation, communications module  512  sends and receives electrical, electromagnetic or optical signals that carry digital data streams representing various types of information. The network link typically provides data communication through one or more networks to other data devices. For example, the network link of the communications module  512  may provide a connection through local network to a host computer or to data equipment operated by an Internet Service Provider (ISP). The ISP in turn provides data communication services through the world wide packet data communication network now commonly referred to as the “Internet.” The local network and Internet both use electrical, electromagnetic or optical signals that carry digital data streams. The signals through the various networks and the signals on the network link and through communications module  512 , which carry the digital data to and from computer system  500 , are example forms of transmission media. 
     Computer system  500  can send messages and receive data, including program code, through the network(s), the network link and communications module  512 . In the Internet example, a server might transmit a requested code for an application program through Internet, the ISP, the local network and communications module  512 . The received code may be executed by processor  502  as it is received, and/or stored in data storage  506  for later execution. 
     In certain aspects, the input/output module  510  is configured to connect to a plurality of devices, such as an input device  514  (e.g., input device  216 ) and/or an output device  516  (e.g., output device  214 ). Example input devices  514  include a keyboard and a pointing device, e.g., a mouse or a trackball, by which a user can provide input to the computer system  500 . Other kinds of input devices  514  can be used to provide for interaction with a user as well, such as a tactile input device, visual input device, audio input device, or brain-computer interface device. For example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, tactile, or brain wave input. Example output devices  516  include display devices, such as a LED (light emitting diode), CRT (cathode ray tube), LCD (liquid crystal display) screen, a TFT LCD (Thin-Film-Transistor Liquid Crystal Display) or an OLED (Organic Light Emitting Diode) display, for displaying information to the user. The output device  516  may comprise appropriate circuitry for driving the output device  516  to present graphical and other information to a user. 
     According to one aspect of the present disclosure, the client  110  and server  130  can be implemented using a computer system  500  in response to processor  502  executing one or more sequences of one or more instructions contained in memory  504 . Such instructions may be read into memory  504  from another machine-readable medium, such as data storage device  506 . Execution of the sequences of instructions contained in main memory  504  causes processor  502  to perform the process steps described herein. One or more processors in a multi-processing arrangement may also be employed to execute the sequences of instructions contained in memory  504 . Processor  502  may process the executable instructions and/or data structures by remotely accessing the computer program product, for example by downloading the executable instructions and/or data structures from a remote server through communications module  512  (e.g., as in a cloud-computing environment). In alternative aspects, hard-wired circuitry may be used in place of or in combination with software instructions to implement various aspects of the present disclosure. Thus, aspects of the present disclosure are not limited to any specific combination of hardware circuitry and software. 
     Various aspects of the subject matter described in this specification can be implemented in a computing system that includes a back end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the subject matter described in this specification, or any combination of one or more such back end, middleware, or front end components. For example, some aspects of the subject matter described in this specification may be performed on a cloud-computing environment. Accordingly, in certain aspects a user of systems and methods as disclosed herein may perform at least some of the steps by accessing a cloud server through a network connection. Further, data files, circuit diagrams, performance specifications and the like resulting from the disclosure may be stored in a database server in the cloud-computing environment, or may be downloaded to a private storage device from the cloud-computing environment. 
     Computing system  500  can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. Computer system  500  can be, for example, and without limitation, a desktop computer, laptop computer, or tablet computer. Computer system  500  can also be embedded in another device, for example, and without limitation, a mobile telephone, a personal digital assistant (PDA), a mobile audio player, a Global Positioning System (GPS) receiver, a video game console, and/or a television set top box. 
     The term “machine-readable storage medium” or “computer-readable medium” as used herein refers to any medium or media that participates in providing instructions or data to processor  502  for execution. The term “storage medium” as used herein refers to any non-transitory media that store data and/or instructions that cause a machine to operate in a specific fashion. Such a medium may take many forms, including, but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical disks, magnetic disks, or flash memory, such as data storage device  506 . Volatile media include dynamic memory, such as memory  504 . Transmission media include coaxial cables, copper wire, and fiber optics, including the wires that comprise bus  508 . Common forms of machine-readable media include, for example, floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, an EPROM, a FLASH EPROM, any other memory chip or cartridge, or any other medium from which a computer can read. The machine-readable storage medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more of them. 
     As used in this specification of this application, the terms “computer-readable storage medium” and “computer-readable media” are entirely restricted to tangible, physical objects that store information in a form that is readable by a computer. These terms exclude any wireless signals, wired download signals, and any other ephemeral signals. Storage media is distinct from but may be used in conjunction with transmission media. Transmission media participates in transferring information between storage media. For example, transmission media includes coaxial cables, copper wire and fiber optics, including the wires that comprise bus  508 . Transmission media can also take the form of acoustic or light waves, such as those generated during radio-wave and infra-red data communications. Furthermore, as used in this specification of this application, the terms “computer,” “server,” “processor,” and “memory” all refer to electronic or other technological devices. These terms exclude people or groups of people. For the purposes of the specification, the terms display or displaying means displaying on an electronic device. 
     In one aspect, a method may be an operation, an instruction, or a function and vice versa. In one aspect, a clause or a claim may be amended to include some or all of the words (e.g., instructions, operations, functions, or components) recited in other one or more clauses, one or more words, one or more sentences, one or more phrases, one or more paragraphs, and/or one or more claims. 
     To illustrate the interchangeability of hardware and software, items such as the various illustrative blocks, modules, components, methods, operations, instructions, and algorithms have been described generally in terms of their functionality. Whether such functionality is implemented as hardware, software or a combination of hardware and software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application. 
     As used herein, the phrase “at least one of” preceding a series of items, with the terms “and” or “or” to separate any of the items, modifies the list as a whole, rather than each member of the list (e.g., each item). The phrase “at least one of” does not require selection of at least one item; rather, the phrase allows a meaning that includes at least one of any one of the items, and/or at least one of any combination of the items, and/or at least one of each of the items. By way of example, the phrases “at least one of A, B, and C” or “at least one of A, B, or C” each refer to only A, only B, or only C; any combination of A, B, and C; and/or at least one of each of A, B, and C. Furthermore, to the extent that the term “include,” “have,” or the like is used in the description or the claims, such term is intended to be inclusive in a manner similar to the term “comprise” as “comprise” is interpreted when employed as a transitional word in a claim. 
     The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. Phrases such as an aspect, the aspect, another aspect, some aspects, one or more aspects, an implementation, the implementation, another implementation, some implementations, one or more implementations, an embodiment, the embodiment, another embodiment, some embodiments, one or more embodiments, a configuration, the configuration, another configuration, some configurations, one or more configurations, the subject technology, the disclosure, the present disclosure, other variations thereof and alike are for convenience and do not imply that a disclosure relating to such phrase(s) is essential to the subject technology or that such disclosure applies to all configurations of the subject technology. A disclosure relating to such phrase(s) may apply to all configurations, or one or more configurations. A disclosure relating to such phrase(s) may provide one or more examples. A phrase such as an aspect or some aspects may refer to one or more aspects and vice versa, and this applies similarly to other foregoing phrases. 
     A reference to an element in the singular is not intended to mean “one and only one” unless specifically stated, but rather “one or more.” The term “some” refers to one or more. Underlined and/or italicized headings and subheadings are used for convenience only, do not limit the subject technology, and are not referred to in connection with the interpretation of the description of the subject technology. Relational terms such as first and second and the like may be used to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions. All structural and functional equivalents to the elements of the various configurations described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and intended to be encompassed by the subject technology. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the above description. No claim element is to be construed under the provisions of 35 U.S.C. § 112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.” 
     While this specification contains many specifics, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of particular implementations of the subject matter. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. 
     The subject matter of this specification has been described in terms of particular aspects, but other aspects can be implemented and are within the scope of the following claims. For example, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. The actions recited in the claims can be performed in a different order and still achieve desirable results. As one example, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the aspects described above should not be understood as requiring such separation in all aspects, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. 
     The title, background, brief description of the drawings, abstract, and drawings are hereby incorporated into the disclosure and are provided as illustrative examples of the disclosure, not as restrictive descriptions. It is submitted with the understanding that they will not be used to limit the scope or meaning of the claims. In addition, in the detailed description, it can be seen that the description provides illustrative examples and the various features are grouped together in various implementations for the purpose of streamlining the disclosure. The method of disclosure is not to be interpreted as reflecting an intention that the claimed subject matter requires more features than are expressly recited in each claim. Rather, as the claims reflect, inventive subject matter lies in less than all features of a single disclosed configuration or operation. The claims are hereby incorporated into the detailed description, with each claim standing on its own as a separately claimed subject matter. 
     The claims are not intended to be limited to the aspects described herein, but are to be accorded the full scope consistent with the language claims and to encompass all legal equivalents. Notwithstanding, none of the claims are intended to embrace subject matter that fails to satisfy the requirements of the applicable patent law, nor should they be interpreted in such a way.