Django-1.2.1/django/contrib/gis/utils/ogrinfo.py

   1 """
   2 This module includes some utility functions for inspecting the layout
   3 of a GDAL data source -- the functionality is analogous to the output
   4 produced by the `ogrinfo` utility.
   5 """
   6
   7 from django.contrib.gis.gdal import DataSource
   8 from django.contrib.gis.gdal.geometries import GEO_CLASSES
   9
  10 def ogrinfo(data_source, num_features=10):
  11     """
  12     Walks the available layers in the supplied `data_source`, displaying
  13     the fields for the first `num_features` features.
  14     """
  15
  16     # Checking the parameters.
  17     if isinstance(data_source, str):
  18         data_source = DataSource(data_source)
  19     elif isinstance(data_source, DataSource):
  20         pass
  21     else:
  22         raise Exception('Data source parameter must be a string or a DataSource object.')
  23
  24     for i, layer in enumerate(data_source):
  25         print "data source : %s" % data_source.name
  26         print "==== layer %s" % i
  27         print "  shape type: %s" % GEO_CLASSES[layer.geom_type.num].__name__
  28         print "  # features: %s" % len(layer)
  29         print "         srs: %s" % layer.srs
  30         extent_tup = layer.extent.tuple
  31         print "      extent: %s - %s" % (extent_tup[0:2], extent_tup[2:4])
  32         print "Displaying the first %s features ====" % num_features
  33
  34         width = max(*map(len,layer.fields))
  35         fmt = " %%%ss: %%s" % width
  36         for j, feature in enumerate(layer[:num_features]):
  37             print "=== Feature %s" % j
  38             for fld_name in layer.fields:
  39                 type_name = feature[fld_name].type_name
  40                 output = fmt % (fld_name, type_name)
  41                 val = feature.get(fld_name)
  42                 if val:
  43                     if isinstance(val, str):
  44                         val_fmt = ' ("%s")'
  45                     else:
  46                         val_fmt = ' (%s)'
  47                     output += val_fmt % val
  48                 else:
  49                     output += ' (None)'
  50                 print output
  51
  52 # For backwards compatibility.
  53 sample = ogrinfo