Talk:Dynamic time warping

message: I think that it would be useful if the formal definition was given, instead of just a code implementation.  The code is useful, but it would be easier to understand if the formal definition was given first.  Also, it would be useful if there was a formal derivation of the algorithm, with proof given of its various properties.  
It would be nice if there was an example or note how can be the DTW array used afterwards. Petulda (talk) 16:28, 19 December 2009 (UTC)
replies: text: The displayed algorithm is actually the Levenstein distance. The Levenstein or string edit distance is a particular case of DTW, when the sequences consist of discrete symbol, and the distance between any two different symbols (including the 'empty' symbol) is 1, and 0 for identical symbols. However, in its most general form, the sequences may consist of continuous feature vectors. I think this should be made clear in the page.   —Preceding unsigned comment added by 131.231.126.100 (talk) 12:04, 16 December 2008 (UTC)

text: No. All algorithms should be in pseudocode. Obviously.65.183.135.231 (talk) 04:37, 20 April 2008 (UTC)
replies: text:  The obviousness escapes me. You can't compare two pseudocodes. 70.225.163.208 (talk) 01:09, 17 June 2011 (UTC)

text: The thing is that if you serialize a 2d sequence (e.g., concatenate the rows of an image), you loose the connections between each pixel and its neighbors above and below, and can match only in the horizontal direction, each row indepent of the other rows. For example, if you want to match the pixels of two images, you get a pretty stripey correspondence map. --IdS (talk) 21:57, 20 March 2011 (UTC)
thread_title: Suggested errors and improvments

message: Please, someone, fix the formatting where it talks about "bold" it doesn't show in the code.  — Preceding unsigned comment added by Gforman44 (talk • contribs) 20:46, 5 October 2016 (UTC)
replies: text: Already fixed.Rgiusti (talk) 13:19, 24 January 2017 (UTC)

text: Series start at s[1] and t[1].Rgiusti (talk) 13:19, 24 January 2017 (UTC)

text: Series start at s[1] and t[1]. If anything in row or column 0 (except DTW[0,0]) is not infinity, the algorithm will produce out-of-bounds matches.Rgiusti (talk) 13:19, 24 January 2017 (UTC)
thread_title: Obsolete

message: It isn't clear why return DTW[n, m] is returned, rather than return DTW.  —DIV (120.18.188.52 (talk) 09:53, 5 July 2018 (UTC)
thread_title:  Pseudocode 

message: A very simple example with concrete numbers/symbols would be useful.  —DIV (120.18.188.52 (talk) 09:54, 5 July 2018 (UTC)
thread_title:  Example 

message: There are sources that claim that Hirschberg's algorithm cannot be used to compute the DTW cost in linear space. This claim seems to be wrong as it relies on an example from the paper SparseDTW: A Novel Approach to Speed up Dynamic Time Warping that was calculated wrongly. It is quite clear that one can find a middle node of the optimal warping path and then recurse on the two new subproblems, as it is simply a shortest path problem in a planar grid graph. AnusserWP (talk) 13:29, 17 September 2021 (UTC)
thread_title:  Linear Space Using Hirschberg's Algorithm 

message: The figure showing a matching between two piecewise linear curves does not show an optimal matching, since it can be improved by assigning the 4th vertex of the upper curve to the 3rd vertex of the lower curve. (The left ends are counted as 1st vertices).
The illustration should be corrected or removed.
AVM2019 (talk) 20:03, 6 September 2022 (UTC)
thread_title:  Figure with 2 piecewise linear curves