How to count the difference between two nested lists in Python?

Question

If I had the two following lists with tuples in the form of (x,y):

 [(a,1),(b,2),(c,7),(d,1)]
 [(a,3),(b,2),(c,7),(d,8)]

I want to count the number of differences with respect to 'y' value for corresponding 'x' values. In the above case, the answer is 2

(a,1) doesn't match with (a,3)

(d,1) doesn't match with (d,8)

EDIT: This is not a duplicate, the position of the elements matter. I want to check if element 1 in list 1 is same as element 1 in list 2 and so on.

this might have been answered here: http://stackoverflow.com/questions/16138015/python-comparing-two-lists — keda, Oct 15 '15 at 20:36
Possible duplicate of [python find difference between two lists](http://stackoverflow.com/questions/22559627/python-find-difference-between-two-lists) — Leb, Oct 15 '15 at 20:38
THis is not a duplicate. I am trying to do something different here — Rakesh Adhikesavan, Oct 15 '15 at 20:39

score 2 · Accepted Answer · answered Oct 15 '15 at 20:40

2

You can use zip function and a generator expression within sum function :

count=sum(i!=j for i,j in zip(list1,list2))

answered Oct 15 '15 at 20:40

Mazdak

score 0 · Answer 2 · answered Oct 15 '15 at 20:44

0

Another method is

x = [("a", 1) ,("b", 2), ("c", 7), ("d", 1)]
y = [("a", 3), ("b", 2), ("c", 7), ("d", 8)]
count = len(set(x).intersection(y))

answered Oct 15 '15 at 20:44

Shawn Mehan

This doesn't take into account position does it? (that x[1] != y[1]), just that there is a difference somewhere in x respective to y? – stian Nov 09 '15 at 08:31

2 Answers2