Is Fiona's collections.OrderedDict immutable?

Question

After opening shapefile I want to use all of its attributes (geometry column, crs, etc), but want to delete the contents of the OrderedDict in the 'properties' key. I want to append new data to it, and write it back to a shapefile. The standard syntax for deleting keys from Python dicts like so

D = {'spam': 2, 'ham': 1, 'eggs': 3}
D.popitem()
('eggs', 3)
D
{'ham': 1, 'spam': 2}

does not apply to the fiona collections object: How can I manipulate a fiona.collection object? Or are those immutable?

Answer 1

Simply use del

import fiona
shape = fiona.open("ashape.shp")
one = shape.next()
print one
{'geometry': {'type': 'Point', 'coordinates': (-0.7989756722151089, 0.5492957746478874)}, 
'type': 'Feature', 'id': '0', 
'properties': OrderedDict([(u'id', 0), (u'test', 5), (u'hello', u'you')])}
# delete one "field"
del one['properties']['hello']
print one
{'geometry': {'type': 'Point', 'coordinates': (-0.7989756722151089, 0.5492957746478874)}, 
 'type': 'Feature', 'id': '0', 
 'properties': OrderedDict([(u'id', 0), (u'test', 5)])}
# add a new "field"
one['properties']['bb']= "hello"
print one
{'geometry': {'type': 'Point', 'coordinates': (-0.58898847631242, 0.17797695262484003)}, 
'type': 'Feature', 'id': '1', 
'properties': OrderedDict([(u'id', 1), (u'test', 5), ('bb', 'hello')])}

If you want to delete all the key/values

 one['properties'].clear()
 print one['properties']
 OrderedDict()
 one['properties']['test'] = 1
 one['properties']
 OrderedDict([('test', 1)])

But be careful, if you modify the properties, you need to modify also the schema of the original shapefile.