topic Re: Unsupported operand error writing to file in Python Questions

Unsupported operand error writing to file

Zeke — Fri, 13 Dec 2013 13:43:05 GMT

In the code below, I get a "TypeError: unsupported operand type(s) for +: 'NoneType and 'str'" on the f.write line. If I don't concatenate, it runs fine, but all the layer names run together.

I understand what the error means, but not why I'm getting a NoneType. I've tried casting lyr.name to str, same result. All I'm trying to do is write out a text file of layer names. Any idea what's causing this and how to get around it? Thanks.

for lyr in arcpy.mapping.ListLayers(mxd, "", df):         f.write(lyr.name) + "\n"         count += 1

Re: Unsupported operand error writing to file

JoshuaChisholm — Fri, 13 Dec 2013 18:44:22 GMT

Hey Greg,

Looks like a simple typo to me. The new line is on the wrong side of the bracket. Try this:

for lyr in arcpy.mapping.ListLayers(mxd, "", df):         f.write(lyr.name + "\n")         count += 1

Good luck!
~Josh

Re: Unsupported operand error writing to file

Zeke — Fri, 13 Dec 2013 20:38:19 GMT

You are right, that was a dumb mistake. Thanks.