python-dwca-reader 0.1.1

Major limitations

• Early support for DwC-A extensions.

• It sometimes assumes the file has been produced by GBIF’s IPT. For example, only zip compression is curently supported, even tough the Darwin Core Archive allows other compression formats.

• No write support.

Installation

Quite simply:

$ pip install python-dwca-reader

Example use

1. Basic use, access to metadata and “Core lines”

from dwca import DwCAReader
from dwca.darwincore.utils import qualname as qn

# Let's open our archive...
# Using the with statement ensure that resources will be properly freed/cleaned after use.
with DwCAReader('my_archive.zip') as dwca:
    # We can now interact with the 'dwca' object

    # We can read scientific metadata (EML) through a BeautifulStoneSoup object in the 'metadata' attribute
    # BeautifulStoneSoup is provided by BS3: http://www.crummy.com/software/BeautifulSoup/bs3/documentation.html
    print dwca.metadata.prettify()

    # We can get inspect archive to discover what is the Core Type (Occurrence, Taxon, ...):
    print "Core type is: %s" % dwca.core_rowtype
    # => Core type is: http://rs.tdwg.org/dwc/terms/Occurrence

    # Check if a Darwin Core term in present in the core file
    if dwca.core_contains_term('http://rs.tdwg.org/dwc/terms/locality'):
        print "This archive contains the 'locality' term in its core file."
    else:
        print "Locality term is not present."

    # Using full qualnames for DarwincCore terms (such as 'http://rs.tdwg.org/dwc/terms/country') is verbose...
    # The qualname() helper function make life easy for common terms.
    # (here, it has been imported as 'qn'):
    qn('locality')
    # => u'http://rs.tdwg.org/dwc/terms/locality'

    # Combined with previous examples, this can be used to things more clear:
    # For example:
    if dwca.core_contains_term(qn('locality')):
        pass

    # Or:
    if dwca.core_rowtype == qn('Occurrence'):
        pass

    # Finally, let's iterate over the archive lines and get the data:
    for line in dwca.each_line():
        # line is an instance of DwCALine

        # Print can be used for debugging purposes...
        print line

        # => --
        # => Rowtype: http://rs.tdwg.org/dwc/terms/Occurrence
        # => Source: Core file
        # => Line ID:
        # => Data: {u'http://rs.tdwg.org/dwc/terms/basisOfRecord': u'Observation', u'http://rs.tdwg.org/dwc/terms/family': # => u'Tetraodontidae', u'http://rs.tdwg.org/dwc/terms/locality': u'Borneo', u'http://rs.tdwg.#
        # => org/dwc/terms/scientificName': u'tetraodon fluviatilis'}
        # => --

        # You can get the value of a specific Darwin Core term through
        # the "data" dict:
        print "Locality for this line is: %s" % line.data[qn('locality')]
        # => Locality for this line is: Mumbai

    # Alternatively, we can get a list of core lines instead of using each_line():
    lines = dwca.lines

    # Or retrieve a specific line by its id:
    occurrence_number_three = dwca.get_line(3)

2. Use of Darwin Core Archives using extensions (star schema)

from dwca import DwCAReader
from dwca.darwincore.utils import qualname as qn

with DwCAReader('archive_with_vernacularnames_extension.zip') as dwca:
    # Let's ask the archive what kind of extensions are in use:
    print dwca.extensions_rowtype
    # => [u'http://rs.gbif.org/terms/1.0/VernacularName']

    # For convenience
    core_lines = dwca.lines

    # a) Data access
    # Extension lines are accessible as a list of DwcALine instances in the 'extensions' attribute:
    for e in core_lines[0].extensions:
        # Display all extensions line that refers to the first Core line
        print e

    # b) We can now see in a given archive, a DwcALine can come from multiple sources...
    # Se we can ask it where it's from:
    print core_lines[0].from_core
    # => True
    print core_lines[0].extensions[0].from_extension
    # => True

    # ... and what its rowtype is:
    print core_lines[0].rowtype
    # => http://rs.tdwg.org/dwc/terms/Taxon

3. Another example with multiple extensions (no new API here):

from dwca import DwCAReader
from dwca.darwincore.utils import qualname as qn

with DwCAReader('multiext_archive.zip') as dwca:
    lines = dwca.lines
    ostrich = lines[0]

    print "You'll find below all extensions line reffering to Ostrich"
    print "There should be 3 verncaular names and 2 taxon description"
    for ext in ostrich.extensions:
        print ext

    print "We can then simply filter by type..."
    for ext in ostrich.extensions:
        if ext.rowtype == 'http://rs.gbif.org/terms/1.0/VernacularName':
            print ext

    print "We can also use list comprehensions for this:"
    description_ext = [e for e in ostrich.extensions if
                   e.rowtype == 'http://rs.gbif.org/terms/1.0/Description']

    for ext in description_ext:
        print ext

Run the test suite

$ pip install nose
$ nosetests

Test coverage can easily be obtained after installing coverage.py

$ nosetests --with-coverage --cover-erase --cover-package=dwca
.....................
Name                    Stmts   Miss  Cover   Missing
-----------------------------------------------------
dwca                        0      0   100%
dwca.darwincore             0      0   100%
dwca.darwincore.terms       1      0   100%
dwca.darwincore.utils       3      0   100%
dwca.dwca                 130     16    88%   23-45
dwca.utils                  5      1    80%   12
-----------------------------------------------------
TOTAL                     139     17    88%
----------------------------------------------------------------------
Ran 21 tests in 0.830s

OK