Renaming files with a sequence number format (001, 002, etc)

renaming_files_sequence.py

# Reducing sample names of QN61 by 1 value to match QN62, QN63 and the DieMap

root_dir = os.path.abspath(path_string)
files = os.listdir(root_dir)
prefix =  ".csv"
files = [file for file in files if prefix in file]
for file in files:
    number = int(file[1:4])-1
#     print("%03d"%number)
    newfile = "S%03d.csv"%number
#     print(newfile)
    os.rename(os.path.join(root_dir,file),os.path.join(root_dir,newfile))
    print("saved to %s"%newfile)
#     print(os.path.join(root_dir,file))