date_regex.py

import re

# 04-20-2009; 04/20/2009; 4/20/09;
date1 = r"\b(0?[1-9]|[12][0-9]|3[01])\b(\s|,|-|\/|.)(\s|,|-|\/|.)?\b(0?[1-9]|[12][0-9]|3[01])\b(\s|,|-|\/|.)(\s|,|-|\/|.)?\b((20(0|1|2)\d)|((0|1|2)\d))\b"

# Monthname Date, Year; Mar 20, 2009;
date2 = r"\b(Jan(uary)?|Feb(ruary)?|Mar(ch)?|Apr(il)?|May|Jun(e)?|Jul(y)?|Aug(ust)?|Sep(tember)?|Oct(ober)?|Nov(ember)?|Dec(ember)?)\b(\s|,|-|\/|.)(\s|,|-|\/|.)?\b(0?[1-9]|[12][0-9]|3[01])(st|nd|th)?\b(\s|,|-|\/|.)(\s|,|-|\/|.)?\b((20(0|1|2)\d)|((0|1|2)\d))\b"

# Date Monthname, Year;  20 March, 2009;
date3 = r"\b(0?[1-9]|[12][0-9]|3[01])(st|nd|th)?\b(\s|,|-|\/|.)(\s|,|-|\/|.)?\b(Jan(uary)?|Feb(ruary)?|Mar(ch)?|Apr(il)?|May|Jun(e)?|Jul(y)?|Aug(ust)?|Sep(tember)?|Oct(ober)?|Nov(ember)?|Dec(ember)?)\b(\s|,|-|\/|.)(\s|,|-|\/|.)?\b((20(0|1|2)\d)|((0|1|2)\d))\b"

# Month, Year; Feb 2009; 12/2009;
date4 = r"\b(Jan(uary)?|Feb(ruary)?|Mar(ch)?|Apr(il)?|May|Jun(e)?|Jul(y)?|Aug(ust)?|Sep(tember)?|Oct(ober)?|Nov(ember)?|Dec(ember)?)\b(\s|,|-|\/|.)(\s|,|-|\/|.)?\b((20(0|1|2)\d)|((0|1|2)\d))\b"

# date_formats_supported = "04-20-2009; 04/20/09; 4/20/09; 4/3/2009; Mar 20, 2009; March 20, 2009; Mar. 20, 2009; Mar 20 2009; 20 Mar 2009; 20 March 2009; 2 Mar. 2009; 20 March, 2009; Mar 20th, 2009; Mar 21st, 2009; Mar 22nd, 2009; Feb 2009; Sep 2009; Oct 2010; 6/2008; 12/2009; 2009; 2010"

ans = "Not Found"

def get_date(text):
	dates = []
	lines = text.split("\n")
	for test_str in lines:
		if 'w.e.f' in test_str.lower():
			continue
		matches = re.finditer(date1, test_str)
		for m in matches:
		    dates += [m.group()]

		matches = re.finditer(date2, test_str)
		for m in matches:
		    dates += [m.group()]

		matches = re.finditer(date3, test_str)
		for m in matches:
		    dates += [m.group()]

		matches = re.finditer(date4, test_str)
		for m in matches:
		    dates += [m.group()]

	print("\nSuspected values for Date: ", dates)
	# print(type(dates[0]))
	return dates[0] if dates else "Not Found"
	# return ans