Package: rasdapy
*RasdaPy is a client API for rasdaman that enables building and
executing rasql queries with python.*Requirementsnumpy, grpcio, protobuf.a running rasdaman instance, seehttp://rasdaman.org/wiki/DownloadInstallationMake sure you have Python 2.7 or newer if using Python 2 and Python
3.4 or newer if using Python 3. If in doubt, run:$ python –versionIf you do not have setuptools, numpy, grpcio, and protobuf installed,
note that they will be downloaded as dependencies of rasdapy with:
pip install rasdapy.UsageA full client is available that demonstrates how to use rasdapy to send
queries to rasdaman and handle the results:http://rasdaman.org/browser/applications/rasdapy/rasql.pyImport RasdaPy core API$ from rasdapy.db_connector import DBConnector
$ from rasdapy.query_executor import QueryExecutorConnect to rasdamanThe DBConnector maintains the connection to rasdaman. In order to
connect it is necessary to specify the host and port on which rasmgr is
running, as well as valid rasdaman username and password.$ db_connector = DBConnector("localhost", 7001, "rasadmin", "rasadmin")Create the query executorQueryExcutor is the interface through which rasql queries (create,
insert, update, delete, etc.) are executed.$ query_executor = QueryExecutor(db_connector)Open the connection to rasdaman$ db_connector.open()Execute sample queriesThe query below returns a list of all the collections available in
rasdaman.$ collection_list = query_executor.execute_read("select c from RAS_COLLECTIONNAMES as c")
$ print(collection_list)Calculate the average of all values in collection mr2.$ result = query_executor.execute_read("select avg_cells(c) from mr2 as c")
$ type(result)Depending on the query the result will have a different type (e.g.
scalar value, interval, array). Each data type is wrapped in a
corresponding class:http://rasdaman.org/browser/applications/rasdapy/rasdapy/modelsSelect a particular subset of each array in collection mr2. This query
will return raw array data that can be converted to a Numpy ndarray.$ result = query_executor.execute_read("select m[0:10 ,0:10] from mr2 as m")
$ numpy_array = result.to_array()Encode array subset to PNG format and write the result to a file.$ result = query_executor.execute_read("select encode(m[0:10 ,0:10], "png") from mr2 as m")
$ with open("/tmp/output.png", "wb") as binary_file:
$   binary_file.write(result.data)Create a rasdaman collection. Note that you should be connected with a
user that has write permission; by default this is rasadmin/rasadmin in
rasdaman, but this can be managed by the administrator.$ query_executor.execute_write("create collection test_rasdapy GreySet")Insert data from a PNG image into the collection. Similarly you need to
have write permissions for this operation.$ query_executor.execute_write("insert into test_rasdapy values decode($1)", "your_path/rasdaman/systemtest/testcases_services/test_all_wcst_import/test_data/wcps_mr/mr_1.png")Alternatively, you can import data from a raw binary file; in this case
it is necessary to specify the spatial domain and array type.$ query_executor.execute_update_from_file("insert into test_rasdapy values $1", "your_path/rasdaman/systemtest/testcases_mandatory/test_select/testdata/101.bin", "[0:100]", "GreyString")Further example queries and a general guide for rasql can be found in
the rasql Query Language guide
(http://rasdaman.org/browser/manuals_and_examples/manuals/doc-guides).Close the connection to rasdaman$ db_connector.close()Best practices:It is recommended to follow this template in order to avoid problems
with leaked transactions:from rasdapy.db_connector import DBConnector
from rasdapy.query_executor import QueryExecutor

db_connector = DBConnector("localhost", 7001, "rasadmin", "rasadmin")
query_executor = QueryExecutor(db_connector)

db_connector.open()

try:
    query_executor.execute_read("...")
    query_executor.execute_write("...")
    # ... more Python code
finally:
    db_connector.close()Development WarningThe Python implementation of Protocol Buffers is not as mature as the
C++ and Java implementations. It may be more buggy, and it is known to
be pretty slow at this time. Since this library relies heavily on
Protocol Buffers and GRPC, it might be prone to occasional hiccups and
unexpected behaviour.ContributorsBang Pham HuuSiddharth ShuklaDimitar MisevThanks also toAlex Mircea DumitruVlad MerticariuGeorge MerticariuAlex ToaderPeter Baumann