Comparing values in two lists in Python

Question

In Python 2.7, I have two lists of integers:

x = [1, 3, 2, 0, 2]
y = [1, 2, 2, 3, 1]

I want to create a third list which indicates whether each element in x and y is identical, to yield:

z = [1, 0, 1, 0, 0]

How can I do this using list comprehension?

My attempt is:

z = [i == j for i,j in ...]

But I don't know how to complete it.

Answer 1

You are looking for zip

z = [i == j for i,j in zip(x,y)]

But you better add int call to get your desired output

>>> z = [int(i == j) for i,j in zip(x,y)]
>>> z
[1, 0, 1, 0, 0]

else you'll get a list like [True, False, True, False, False]

---

As ajcr mentions in a comment, it is better to use itertools.izip instead of zip if the lists are very long. This is because it returns an iterator instead of a list. This is mentioned in the documentation

Like zip() except that it returns an iterator instead of a list.

demo

>>> from itertools import izip
>>> z = [int(i == j) for i,j in izip(x,y)]
>>> z
[1, 0, 1, 0, 0]

Answer 2

You can change it a little bit and do:

[x[i] == y[i] for i in xrange(len(x))]

If you use Python3 - change xrange to range