Merging all feature classes with same name nested in multiple geodatabases using ArcPy says feature class already exists?

Question

I'm following very closely this topic Merging all feature classes with same name nested in multiple geodatabases using ArcPy?, it seems very useful to my python script

this is the script I following from made by Emil Brundage (answered Sep 8 '17 at 15:21):

import arcpy
import os

workspace = "C:/Wiley/P1/gis"
outdir = "C:/Wiley/P1/gis/HK80.gdb"

walk = arcpy.da.Walk(workspace, datatype="FeatureClass", type="Polygon")
di = {}

for dirpath, dirnames, filenames in walk:
          for filename in filenames:
             fcFullPath = os.path.join(dirpath, filename)
             #try adding feature class to dictionary with already-existing key
             try: di [filename] += [fcFullPath]
             #key not in dictionary yet. Create key
             except: di [filename] = [fcFullPath]

#iterate dictionary
for filename in di:
    #get merge feature classes
    mergeFcs = di [filename]
    output = os.path.join(outdir, os.path.basename(fcFullPath) + "_merge")
    arcpy.Merge_management(mergeFcs, output)

However, when I run the script I get a message error show up, a feature class already exists. The script does exactly what I want, but how could I fix the script to avoid this error type.

Following the suggestion from amasephy add the arcpy.Exists and arcpy.Delete_management function on my script:

workspace = r'...\GDBESTATALES_PRUEBA'
outdir = r'...\GDB_Nacional.gdb'

walk = arcpy.da.Walk(workspace, datatype="FeatureClass", type="Polygon")
di = {}

for dirpath, dirnames, filenames in walk:
          for filename in filenames:
             fcFullPath = os.path.join(dirpath, filename)
             #try adding feature class to dictionary with already-existing key
             try: di [filename] += [fcFullPath]
             #key not in dictionary yet. Create key
             except: di [filename] = [fcFullPath]

#iterate dictionary
for filename in di:
    #get merge feature classes
    mergeFcs = di [filename]
    output = os.path.join(outdir, os.path.basename(fcFullPath) + "_merge")
    arcpy.Merge_management(mergeFcs, output)
    if arcpy.Exists(output):
     arcpy.Delete_management(output)

However, nothing happens what I want it, the only one happens is the script takes the last geodatabase and save the last feature class in the other feature class (GDB_Nacional.gdb), that's all.

Answer 1

Try using the arcpy.Exists function. If the output name exists, then append a numerical digit to the output. Alternatively, use arcpy.Delete_management to delete the feature that already exists.