"""
This module includes some utility functions for inspecting the layout
of a GDAL data source -- the functionality is analogous to the output
produced by the `ogrinfo` utility.
"""
from django.contrib.gis.gdal import DataSource
from django.contrib.gis.gdal.geometries import GEO_CLASSES
def ogrinfo(data_source, num_features=10):
"""
Walks the available layers in the supplied `data_source`, displaying
the fields for the first `num_features` features.
"""
# Checking the parameters.
if isinstance(data_source, str):
data_source = DataSource(data_source)
elif isinstance(data_source, DataSource):
pass
else:
raise Exception('Data source parameter must be a string or a DataSource object.')
for i, layer in enumerate(data_source):
print "data source : %s" % data_source.name
print "==== layer %s" % i
print " shape type: %s" % GEO_CLASSES[layer.geom_type.num].__name__
print " # features: %s" % len(layer)
print " srs: %s" % layer.srs
extent_tup = layer.extent.tuple
print " extent: %s - %s" % (extent_tup[0:2], extent_tup[2:4])
print "Displaying the first %s features ====" % num_features
width = max(*map(len,layer.fields))
fmt = " %%%ss: %%s" % width
for j, feature in enumerate(layer[:num_features]):
print "=== Feature %s" % j
for fld_name in layer.fields:
type_name = feature[fld_name].type_name
output = fmt % (fld_name, type_name)
val = feature.get(fld_name)
if val:
if isinstance(val, str):
val_fmt = ' ("%s")'
else:
val_fmt = ' (%s)'
output += val_fmt % val
else:
output += ' (None)'
print output
# For backwards compatibility.
sample = ogrinfo
|