Union analysis fails to execute

[RichardThurau]

Anyone see what's causing this tool to fail?

Gridnums = range(1,18)

for i in Gridnums:
    #vis6class = ws + "/" + "TVvis6class_G" + str(i)
    inList = arcpy.ListFeatureClasses("*ProcGrid_"+str(i), "")
    print "inList: " + str(inList)
    arcpy.Union_analysis(InList, ws + "/" + "TVvis6class_G" + str(i))

Error Code:
inList: [u'Road_ProcGrid_1', u'FPs_S_ProcGrid_1', u'er_di_ProcGrid_1', u'TV_v_ProcGrid_1']

Traceback (most recent call last):
  File "E:\Projects\TV\01_Python\LandCover\LC_2_Vector_Tile_6class_091312.py", line 48, in <module>
    arcpy.Union_analysis([InList], ws + "/" + "TVvis6class_G" + str(i))
  File "C:\Program Files\ArcGIS\Desktop10.0\arcpy\arcpy\analysis.py", line 483, in Union
    raise e
RuntimeError: Object: Error in executing tool
>>>



It's making a good list. I've tried messing with the output format.

Any suggestions, much appreciated!!

Rich

[ChristopherThompson]

Out of curiousity what license level are you running? and how many items are in inList?  If you are at anything below the ArcInfo (or perhaps advanced i think is the new terminology.. ?) I don't think the union tool accepts more than two inputs.

[RichardThurau]

True. I am Info (advanced). Manually using the tool works fine, so error must be in the Python.

Thanks.

RT

[ChristopherThompson]

I suspect they way the output is being created is your problem

ws + "/" + "TVvis6class_G" + str(i))

See if you can enclose that entire term inside double quotes and see if that works out.
So something like this might be what it looks like:

"'" + ws + "/" + "TVvis6class_G" + str(i)) + "'"

[RichardThurau]

No Dice. Took a while to get back to this.

Another one of these cases where a lot of people are looking but no one has any suggestions?

Am I doing something so fundamentally wrong that folks think it's hopeless?

Is there a better way to line this up that makes sense?

Is this really something that shouldn't be going wrong, but is?

Do I need to post more info? The error code is exceptionally meaningless in this case.

I really don't want to revert to using ArcToolbox. Please, please!

Current code:

for i in Gridnums:
    vis6classi = "'" + ws + "/" + "TVvis6class_G" + str(i) + "i" + "'"
    inList = arcpy.ListFeatureClasses("*ProcGrid_"+str(i), "")
    print "inList: " + str(inList)
    arcpy.Union_analysis(InList, vis6classi)
    print "Union completed for Grid " + str(i)

same error.

RT

[ThomasEmge]

Please do print the variable vis6classi and take a look what it currently contains.

My guess would be that it is pointing to a location/workspace that isn't correctly formulated.

If you are able to post your complete script or a more extended section showing where the workspace originates that would be great.

Thanks,
- Thomas

[RichardThurau · Accepted solution]

Turns out I had an empty geography as one of my union inputs. When I tested the tool, it was within a study site where the geography had data. The first union the code was calling was using a dataset that had no data in the analysis area.

RT

[ChristopherThompson]

Don't you just hate that?  Glad you found the error!

[JamieKass]

I am getting the exact same error, but my input is just one feature class (in order to find overlapping regions). It is called within a Python Toolbox workflow, and consistently throws this error. When I run it outside the tool run session, it works fine. Maddening. Any clues as to what might be going on?

[JamieKass]

Just solved it. I never had this issue before, but perhaps this is a new limitation in 10.1? The input parameter to Union must be a list, at least in my case. I put the single input into a list, i.e.

arcpy.Union_analysis([input], output)

and my tool runs smoothly. If this is a hard rule, it should be emphasized in the tool help.