Using %i%".csv" in ArcPy to name output CSV file?

Question

I am using arcpy to describe datasets and output the results into a csv file. I am doing this via a script in arctoolbox and would like to save the file in the same folder as the file being analysed. I don ́t want to overwrite any existing files, and thus would like to simply add a number to the file name.

In the FieldCalculator we can use %i% or %n% to have a variable suffix - for example if my output txt file is called output.txt and a second output.txt is created, this is automatically changed to output01.txt

I want to do the same with ModelBuilder but if I can ́t use %i%.

import arcpy, os
from arcpy import env
import os.path
env.overwriteOutput = True
#Enter FeatureClass path in modelbuilder dialog
fc = arcpy.GetParameterAsText(0)
ischecked = arcpy.GetParameterAsText(1)
#Get FeatureClass name
fcname = os.path.basename(fc)
#define Output Directory
outputTxtFilePath = "PATH"
#Define filename
outputTxtFilename = "\\"+fcname+ %i% +".txt"
#full path of file
outputTxtFile = outputTxtFilePath+outputTxtFilename
# Create a list of fields using the ListFields function
fields = arcpy.ListFields(fc)
#open csv file
csv = open(outputTxtFile,'w')
#write describe results to txt file
csv.write(fc)
for field in fields:
 #create string
 txtStr = "Feldname: {0} \n Type: {1} \n Länge {2}".format(field.name, field.type, field.length) + '\n' 
 csv.write(txtStr)
csv.close()
#Open the txt file if is checked
if str(ischecked) == 'true':
 os.system('notepad '+outputTxtFile)
else:
 exit

it works ok if I remove %i%, but then each file gets overwritten.

• TsvGis: is %i% meant to represent the date or number?
• PolyGeo: Would you be able to edit your question to include a code snippet that works up to the point where you are stuck, please? For any ArcPy questions I think providing a code snippet is your best starting point to attract potential answerers here.
• Robert Buckley: yes...ArcGIS can use %i% for an integer or %n% for an existing name.
• PolyGeo: Using %i% for an integer or %n% for an existing name seems to be a ModelBuilder thing and unrelated or only loosely related to ArcPy and GetParameterAsText. Can you include a code snippet to show how you are using it here, please?
• TsvGis: doh, I just finished some code for this (ill save it for now), but like @PolyGeo said, code snippet would be good just to see how its put together

Answer 1

You could add a python function that pulls any number value from the defined output text file name and adds or assigns 1 to it:

def getValue(x): 
 try:
 return ''.join(i for i in x if i.isdigit()) 
 except ValueError:
 pass
fcname = os.path.basename(fc)
fcnameNoEXT = fcname.split('.')[0]
i = 1
if os.path.exists(fc):
 value = getValue(fcname)
 if value:
 newValue = i + int(value)
 outputTxtFilename = "\\"+fcnameNoEXT.replace(str(value),str(newValue))+ ".txt"
 else:
 outputTxtFilename = "\\"+fcnameNoEXT+ "{}.txt".format(i)