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I am trying to clip a shapefile based on the extents of a smaller raster. I find the extent of the raster using this code:

Extents = arcpy.sa.Raster(MyRaster).extent`

Then, I use these lines to make a polygon out of these extents:

pnt_array = arcpy.Array()
pnt_array.add(Extents2.lowerLeft)
pnt_array.add(Extents.lowerRight)
pnt_array.add(Extents.upperRight)
pnt_array.add(Extents.upperLeft)
poly = arcpy.Polygon(pnt_array)

Finally, I cut clip my shapefile using this code

arcpy.Clip_analysis(shp, poly, Shp_clip)

The problem is that I am using accuracy in two places. Please take a look:

Extents.XMax =                          -86.22649016383502
poly.extent.XMax =                      -86.22650146484375
arcpy.Describe(Shp_clip).extent.XMax=   -86.22650146517043

Is there anyway that I can get a clipped shapefile with the extent exactly as Extents?

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Yes, the extent isn't accurate. If you have spatial analyst extension then use IsNull to create a binary raster, raster to polygon (no simplify) and then dissolve with no fields to create a clipping polygon.

Once you've got that then just clip as normal.

If you haven't got Spatial Analyst then it's a bit more tricky.

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  • I do have spatial analyst toolbox. I am going to give it a try and will post the result.
    – ahoosh
    Commented Jul 14, 2014 at 21:48
  • Your method works great. Though, it is still not accurate enough to the extent I want. Eventually, I want to convert the clipped shapefile into a 1/0 raster with the cells exactly as the raster. When I use feature to raster, I end up with a raster with 1635, 544 columns and rows rather than 1635, 543. I have 1 row less although I am using the exact same cell size when using feature to raster!
    – ahoosh
    Commented Jul 14, 2014 at 22:27
  • Are you setting your snap raster to the existing raster?
    – Michael Stimson
    Commented Jul 14, 2014 at 22:29
  • What do you mean by snap raster? I am using the clipped shapefile shp_clp as input to make a raster out of it using this code: arcpy.FeatureToRaster_conversion(shp_clp, Dummy_Int, output_raster, input_raster) where I use cell size of input_raster in the code.
    – ahoosh
    Commented Jul 14, 2014 at 22:36
  • Snap raster is an environment setting resources.arcgis.com/en/help/main/10.2/index.html#//… that ensures the output cells align perfectly with an existing raster. Also consider output extent environment setting, that may help.
    – Michael Stimson
    Commented Jul 14, 2014 at 22:52

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