rss - Python: efficient comparison of strings in lists -

i monitoring rss feed using feedparser. feed has 100 items , extracting time stamp unique identifier in form of list of strings. single item looks of list like: 2017-07-25t20:41:59-04:00 next, doing python magic other data feed parsed lists (same index, different lists though) extract information want. part works well, love it.

now problem: after time delay

import time time.sleep(60)

i'd monitor feed again , see efficiently if time stamp observed before. if so, i'd pass on executing code , wait more until uniqe time stamp shows up.

i failed implement far. thought making second list , comparing two. each list has 100 items. new items appear on top of feed , move down on time. should fine if run first match. should make code more efficient comparing everything.

i'd happy iif point me towards solution. stuck whatever have tried, failed.

edit:

def compare(feed_id_l, feed_id_check_l): #compares items in lists , returns index in range(0, len(feed_id_l)):     j in range(0, len(feed_id_check_l)):         if feed_id_l[i] == feed_id_check_l[j]:             print('match id ' + feed_id_l[i])             return i, j         else:             return -1 

works , returns 0, 0 if first feed item unchanged.

i have figure out other cases, let's 0, 6.

cheers!