Batch Union Features

These scripts allow batch unioning of shapefiles in a target folder into a new shapefile. The features must be the same data type (points, lines, or polygons).

Union Tool

This script uses the Union tool, which needs the following parameters:

• A list of feature classes with their complete path separated by #;. Example: "C:\\Myfolder\\shape1.shp #;C:\\Myfolder\\shape2.shp #;C:\\Myfolder\\shape3.shp"

• The name of the output feature

import arcpy

# Set the workspace where shapefiles are
workfolder = "E:\\myfolder"
arcpy.env.workspace = workfolder

# List all features in the folder
features = arcpy.ListFeatureClasses()

# Remove the first shapefile from list with pop([position])
firstfc = features.pop(0)

# Create the string to define the input parameter
infeatures = workfolder + "\\" + firstfc

# Iterate the features in the list
for feature in features:
    # Add the separating characters, the path, and the feature name
    infeatures += " #;" + workfolder + "\\" + feature

# Define the output feature
outfeature = workfolder + "\\union.shp"

# Process the union of features
arcpy.Union_analysis(infeatures, outfeature)

Update Tool

The Union tool adds fields from every input feature to the output attribute table. To get an output with the same fields as the input features, use the Update tool instead — but it works only with a pair of features at a time.

It is necessary to create temporary files as intermediate results of every update. Processing n features will produce n-2 intermediate files plus the final result.

import arcpy

# Set the workspace where shapefiles are
workfolder = "D:\\Temp"
arcpy.env.workspace = workfolder

# List all features in the folder
features = arcpy.ListFeatureClasses()

# Remove the first and second shapefile from the list
firstfc = workfolder + "\\" + features.pop(0)
secondfc = workfolder + "\\" + features.pop(0)

# Define the output name of the first update
firstupdate = workfolder + "\\update0.shp"

# Process the first update
arcpy.Update_analysis(firstfc, secondfc, firstupdate)

# Iterate the other features in the list and enumerate them from 0
for position, feature in enumerate(features):
    # Process all features except the last one
    if position < (len(features) - 1):
        # Define one input name from the list of features
        infc = workfolder + "\\" + feature
        # Define the other input name according to its position
        inupdate = workfolder + "\\update" + str(position) + ".shp"
        # Define the output name (adding 1 to be the input for next cycle)
        outupdate = workfolder + "\\update" + str(position + 1) + ".shp"
        arcpy.Update_analysis(infc, inupdate, outupdate)
    # Process the last iteration
    if position == (len(features) - 1):
        infc = workfolder + "\\" + feature
        inupdate = workfolder + "\\update" + str(position) + ".shp"
        # Define the final output feature name
        outupdate = workfolder + "\\final_update.shp"
        arcpy.Update_analysis(infc, inupdate, outupdate)