NEWBIE QUESTIION: Comparing Lists in Python

[Mark McEahern]

[Dianne van Dulken]
> I want to return the difference between the two lists as again two lists
> 
> eg:
> 
> list 1 = item1, item5, item8, item10
> list2 = item 3, item4, item5
> 
> I want to return
> 
> returnlist1 = item1, item8, item10
> returnlist2 = item3, item4

You can do this easily with list comprehension.  Here's a demo...

#!/usr/bin/env python

def not_in_list(l1, l2):
  """
  Return a list of elements from l1 that are not in l2.
  """
  return [x for x in l1 if x not in l2]

l1 = [1,5,8,10]
l2 = [3,4,5]

print not_in_list(l1, l2)
print not_in_list(l2, l1)

// mark