Python: How do I use a list loop with the buffer analysis tool to create three buffer zones with user input distance in feet?

Question

I think I can make my analysis work if I can fill in the blanks.  I know the first two and the distanceList values, but beyond that everything I have tried does not work.

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DavidPike · Answer

I can only guess it wants you to pass them as parameters before the list rather than as magic numbers e.g

buff_dist1 = 100

buff_dist2 = 200

buff_dist3 = 300

distanceList = [ buff_dist1' ....

Also be aware your "riverbuffer" + ".shp" needs to change name during the iteration to reflect the input distance. Currently it will just overwrite with the same name.

Use something like

"Riverbuffer_" + str(distance) + "_ft.shp"

CateEliz · Answer

Thank you so much!  What you did makes sense.  I am trying to fit that to the template I have since I am only supposed to fill in the blanks, but I cannot figure out how to fill the three middle lines without having to change the rest of the code, which I do not think we are supposed to do.  All of the lines are to have something filled in, but those three do not seem necessary for it to work, so I am not sure what would go there. Possibly argument variables?  But I think if I did that then I would need to also import sys and change the parameters listed within the buffer analysis.

DavidPike · Answer

#set a list of 100, 200 and 300ft #variables should be snake case btw... distanceList = [100, 200, 300] #buffer river by ieterating values supplied in distanceList #for every number in distanceList, input this numbe as a variable in the #buffer function below #within the for loop, the 'distance' variable will represent a distance in your list #If you dont pass this in with 'Feet' it will default to metres #for the out_feature_class, I'll take this distance value, covert it to a string (str) #and add it on to the end of the buffer name (concatenating). for distance in distance_List: out_feature_class = "riverbuffer_" + str(distance) + "_ft" # turn your distance into a string with 'Feet' on the end #e.g. "100 Feet" distance_ft = str(distance) + " Feet" arcpy.Buffer_analysis(in_features, out_feature_class, distance_ft)‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ print "buffer for distance " + distance_ft + " is done"‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍