Python GDAL and Fiona: How to Resolve NoneType Error in Raster Clipping

fionagdalpython

I am using the following code to first divide a vector layer to many polygons and after that use them to clipping parts of a raster layer. The Name attribute in the vector data has a text data type. I am not sure why I receive the error of 'NoneType' object is not subscriptable. Can anyone help me to solve this error?

import glob
import gdal
import fiona

with fiona.open('E:/data/vector.shp', 'r') as dst_in:
    for index, feature in enumerate(dst_in):
        with fiona.open('E:/data/polygons/NO_{}.shp'.format(index), 'w', **dst_in.meta) as dst_out:
            dst_out.write(feature)

polygons = glob.glob('E:/data/polygons/*.shp')  ## Retrieve all the .shp files

for polygon in polygons:
    feat = fiona.open(polygon, 'r')
    name = feat['properties']['Name']  
    command = 'gdalwarp -dstnodata -9999 -cutline {} ' \
              '-crop_to_cutline -of GTiff E:/data/raster.tif E:/data/outputraster/NO_{}.tif'.format(polygon, name)

TypeError                                 Traceback (most recent call last)
<ipython-input-3-ad6d7471adf6> in <module>
      1 for polygon in polygons:
      2     feat = fiona.open(polygon, 'r')
----> 3     name = feat['properties']['Name']
      4     command = 'gdalwarp -dstnodata -9999 -cutline {} ' \
      5               '-crop_to_cutline -of GTiff E:/data/raster.tif E:/data/outputraster/NO_{}.tif'.format(polygon, name)

TypeError: 'NoneType' object is not subscriptable

Best Answer

polygons in your script are not polygons/features. They are shapefiles. fiona.open returns an opened Collection object. That means feat in your code is not a feature, it is a feature collection. You must iterate over the collection to get features.

Use like this:

shapefiles = glob.glob('E:/data/polygons/*.shp')

for shapefile in shapefiles:
    features = fiona.open(shapefile, 'r')
    for feat in features:
         name = feat['properties']['Name']
         ...
         ...
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