Incrementing number in file name when file exists

Question

I am still very new to Python (3). I have a BUNCH of sensor data, but the download limit forces me to retrieve the data in chunks instead of all at once (each .zip file downloaded contains a folder of .csv files for each sensor's data during a given time period). Thus, I have dozens of large .csv files distributed among several folders that I would eventually like to concat/merge/append into one .csv file for each sensor's full data. To make things more complicated, .csv file names for each sensor are identical across the folders. I have developed the following code to rename and move the files into one folder so that later I can concat/merge/append. It works fine except for the fact that the number I am inserting into the new file name is not incrementing.

import os
path = r"C:\directory\sensordatafolders" #folders with .csv files
newPath = r"C:\directory\new" #destination for renamed files
for root, dirs, files in os.walk(path):
    for name in files:
        base, extension = os.path.splitest(name)
        if not os.path.exists(os.path.join(newPath, base + extension))
             oldfile = os.path.join(os.path.abspath(root), name)
             newfile = os.path.join(newPath, base + extension)
             os.rename(oldfile, newfile)
        else:
             i = 1
             oldfile = os.path.join(os.path.abspath(root), name)
             newfile = os.path.join(newPath, base + '_' + str(i) + extension)
             i +=1
             os.rename(oldfile, newfile)

After the second loop (*.csv and *_1.csv files successfully moved), it gives me the 'cannot create a file when that file already exists' error. This is because (I think) it keeps trying to create *_1.csv files instead of incrementing to *_2.csv, etc..

Answer 1

Your

i = 1 

After else should not be there, it keeps setting i to 1 thus always making i's value in to a 2, try to have it outside of the for statements