Hi Ari,
cascaded_union() expects the argument to be a sequence of geometries,
either a multi-part geometry or a list of geometries. The problem with
OGR's shapefile driver is that it can give you LineStrings and
MultiLineStrings from a single file. Until I have a patch for Shapely or a
new release, I'll have to ask you to test the input items and wrap them in
a list if they are single-part geometries. Something like this:
for item in input:
geom = shape(item['geometry'])
if not geom.type.startswith('Multi'):
geom = [geom]
dissolve_feat = cascaded_union(geom)
...
On Mon, Jun 9, 2014 at 4:55 PM, Ari Simmons <ari.ucb.f...@gmail.com> wrote:
> This is my first time trying a cascaded_union, and I am getting the
> following "..no len()..." error. I don't seem to have any 'NoneType'
> geometry..so I'm not sure what it is picking up on...anybody else see it?
>
> >>Traceback (most recent call last):
> >> File "<stdin>", line 1, in <module>
> >> File "I:/It_25/116609_global_hwy_shields/dissolve/dissolve.py", line
> 17, in >>dissolve
> >> dissolve_feat = cascaded_union(geom)
> >>File "C:\Python27\lib\site-packages\shapely\ops.py", line 112, in
> >>cascaded_union
> >> L = len(geoms)
> >>TypeError: object of type 'LineString' has no len()
>
> import fiona
> from shapely.geometry import shape
> from shapely.ops import cascaded_union
>
> def dissolve(inFile, outFile):
> with fiona.open(inFile, 'r', encoding='utf-8') as input:
> input_driver = input.driver
> input_crs = input.crs
> input_schema = input.schema.copy()
> with fiona.open(outFile, 'w', driver=input_driver, crs=input_crs,
> schema=input_schema, encoding='utf-8') as output:
> for item in input:
> geom = shape(item['geometry'])
> dissolve_feat = cascaded_union(geom)
> output.write({'geometry':mapping(dissolve_feat),
> 'properties': item['properties']})
>
>
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>
>
--
Sean Gillies
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