Shapefile Naming conventions in ArcPy?

Question

I have shapefile named `band-tailed_pigeon.shp which is fine and no problem on displaying or geoprocessing on Desktop but in ArcPy when I try to merge some layes to it I am getting this error

ExecuteError: ERROR 000354: The name contains invalid characters

Failed to execute (Merge).

I tried to do the proccess with a simple name like sample.shp which it works but I HAVE TO keep the same name as we are using them in several projects.

Here is the code which I have

FinaloutLocation = "E:\\GIS\\Data\\Final\\band-tailed_pigeon.shp"
inFeaturesToMerge = [dissolve_1, dissolve_2, dissolve_3, dissolve_4, dissolve_5]
arcpy.Merge_management(inFeaturesToMerge, FinaloutLocation)

Answer 1

The problem is with the dash (-) in the shapefile name. This restriction is from geoprocessing tool and not the shapefile name since you can have dashes in your shapefile name.

Some Geoprocessing methods allow you to validate table (feature class) and field names. Consider using either the ValidateTableName or ValidateFieldName function to ensure your names are valid

Answer 2

If you're having issues with shapefile names, a quick script before your merge to find the culprits and make a new copy of the shapefiles will fix the problem. Iterate through each shapefile, test its name, and copy if needed. Merge, then delete whatever new shapefiles you created.

Something like this (untested):

import arcpy
import os

inFeaturesToMerge = [dissolve_1, dissolve_2, dissolve_3, dissolve_4, dissolve_5]

#empty list for merge
mergeFcs = []

#empty list for delete
garbage = []

#iterate feature classes
for fc in inFeaturesToMerge:

    #directory of shapefile
    shpPath = os.path.dirname (fc)

    #set workspace to shapefile directory
    arcpy.env.workspace = shpPath

    #Get shapefile name
    shpName = os.path.basename (fc)

    #Check shapefile name to see if it's kosher
    if not shpName.lower().replace ("_", "").rstrip (".shp").isalnum():

        #Create unique name
        uName = arcpy.CreateUniqueName ("file.shp")

        #create new shapefile with new legit name
        arcpy.CopyFeatures_management (fc, uName)

        #add to list to be merged
        mergeFcs += [uName]

        #add to list to be deleted
        garbage += [uName]
    else:
        #add legit name to merge feature classes
        mergeFcs += [fc]


#merge
arcpy.Merge_management(mergeFcs, FinaloutLocation)

#Clean up
for trash in garbage:
    arcpy.Delete_mangement (trash)

A faster variation on this script is to use Rename_management, rename the culprits, and then change the name back after the merge. This one's a bit dangerous though, as if it fails halfway though you'll have lost some file names:

import arcpy
import os

inFeaturesToMerge = [dissolve_1, dissolve_2, dissolve_3, dissolve_4, dissolve_5]

#empty list for merge
mergeFcs = []

#empty dictionary to track renames
nameChangeDi = {}

#iterate feature classes
for fc in inFeaturesToMerge:

    #directory of shapefile
    shpPath = os.path.dirname (fc)

    #set workspace to shapefile directory
    arcpy.env.workspace = shpPath

    #Get shapefile name
    shpName = os.path.basename (fc)

    #Check shapefile name to see if it's kosher
    if not shpName.lower().replace ("_", "").rstrip (".shp").isalnum():

        #Create unique name
        uName = arcpy.CreateUniqueName ("file.shp")

        #create new shapefile with new legit name
        arcpy.Rename_management (fc, uName)

        #Add changed name to dictionary
        nameChangeDi [uName] = fc

        #add to list to be merged
        mergeFcs += [uName]

    else:
        #add legit name to merge feature classes
        mergeFcs += [fc]


#merge
arcpy.Merge_management(mergeFcs, FinaloutLocation)

#Rename back changed shapefiles
for newName in nameChangeDi:
    arcpy.Rename_management (newName, nameChangeDi [newName])