renameDates.py

#! python3
# renameDates.py - Renames filenames with American MM-DD-YYY date format
# to European DD-MM-YYYY


import shutil, os, re

# Create a regex that matches files with the American date format.
datePattern = re.compile(r"""^(.*?)  	# all text before the date
	((0|1)?\d)-							# one or two digits for the month
	((0|1|2|3)?\d)-						# one or two digits for the day
	((19|20|)\d\d)						# four digits for the year
	(.*?)$								# all text after the date
	""", re.VERBOSE)

# Loop over the files in the working directory.
for amerFilename in os.listdir('.'):
	mo = datePattern.search(amerFilename)


# Skip files without a date.
	if mo == None:
		continue

# Get the different parts of the filename.
	beforePart = mo.group(1)
	monthPart = mo.group(2)
	daypart = mo.group(4)
	yearPart = mo.group(6)
	afterPart = mo.group(8)
# Form the European-style filename.
	euroFilename = beforePart + dayPart + '-' + monthPart + '-' + yearPart + afterPart

# Get the full, absolute file paths.
	absWorkingDir = os.path.abspath('.')
	amerFilename = os.path.join(absWorkingDir, amerFilename)
	euroFilename = os.path.join(absWorkingDir, euroFilename)
# Rename the files.
	print('Renaming "%s" to "%s"...' % (amerFilename, euroFilename))
	# shutil.move(amerFilename, euroFilename) # uncomment after testing