Count the identical pairs in two lists

One way would be to map both lists with operator.eq and take the sum of the result:

from operator import eq

a = [1,2,3,4,2,7,3,5,6,7]
b = [1,2,3,1,2,5,6,2,6,7]

sum(map(eq, a, b))
# 6

Where by mapping the eq operator we get either True or False depending on whether items with the same index are the same:

list(map(eq, a, b))
# [True, True, True, False, True, False, False, False, True, True]

In a one-liner:

sum(x == y for x, y in zip(a, b))

You can use some of Python's special features:

sum(i1 == i2 for i1, i2 in zip(a, b))

This will

pair the list items with zip()
use a generator expression to iterate over the paired items
expand the item pairs into two variables
compare the variables, which results in a boolean that is also usable as 0 and 1
add up the 1s with sum()

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