I have managed to do this manually at Geoprocessing>Environments>Processing Extent and setting the shapefile in the drop down bar.

I was wonder if this could be automated with a python script?

My goal is to create a loop to change the processing extent prior to using spatial analysis tools on a various rasters that represent the areas of the shapefiles. This will keep their extent size minimal.

Edit (Current Code): (Not working)

for i in range (31):
... arcpy.env.extent = (r"C:\Folder\Shapefile"+str(i)+".shp")

Receiving a runtime error stating "Error in accessing environment "

  • so I don't define what str (i) is?
    – JC11
    Feb 7, 2014 at 20:34
  • You already defined i in your for loop
    – user2856
    Feb 7, 2014 at 22:31

2 Answers 2


Yes. As per the the extent help, set arcpy.env.extent = 'path to shapefile' (assuming ArcGIS 10+ as you didn't specify). Don't forget to set the Snap Raster environment so your output raster isn't shifted.

  • I set my extent in a loop and received the runtimeerror: error in accessing environment <extent> Here is my code: for i in range (31): ... arcpy.env.extent = (r"E:\data\Shapefile"+str(i)) Is something stated wrong here?
    – JC11
    Feb 7, 2014 at 19:50
  • you are missing the + ".shp" after str(i)
    – radouxju
    Feb 7, 2014 at 19:56
  • @radouxju: I've added the +".shp" after str (i). Still giving the same error. I'll post the code as an edit in the question.
    – JC11
    Feb 7, 2014 at 20:09
  • 2
    Took a break from attempting this. Tried again with the same code, worked fine. No idea what was wrong before.
    – JC11
    Feb 14, 2014 at 19:58

here is another approach, with some test in the loop to help you identify if something goes wrong :

import arcpy

fcs = arcpy.ListFeatureClasses("C:\\folder\\Shapefile_root*") #shapefile_root is the start of the name of your shapefile

for fc in fcs:
    print fc #just checking that you are looping on the good shp
    arcpy.env.extent = fc
    print arcpy.env.extent # checking that the extent is updated
  • I haven't managed to get this code to work. When i type fc, it trys to autocomplete it to fcs. Nothing prints
    – JC11
    Feb 7, 2014 at 20:39
  • what do you have when you type "fcs" (it should be an object) ? Is your indentation in the "for" loop correct ?
    – radouxju
    Feb 7, 2014 at 20:43
  • you should try copying this script and launching it as a stand alone. Make sure that your path is correct (once it is E, once it is C in your question)
    – radouxju
    Feb 7, 2014 at 20:47

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