CODEWITHSUNDEEP
pythonlist
Leonardo Moreira
Leonardo Moreira

Reputation: 11

Comparing two lists each elements together

I want to compare two lists (list a and list b).

For example:

list a = [a1, a2, a3, a4, a5]

list b = [b1, b2, b3, b4, b5]

if we have...

a1 == b1
a2 == b2
a3 == b3
a4 == b4
a5 == b5

Result: 5

Other example:

list 1 = [1, 2, 3, 4, 5]

list 2 = [1, 7, 9, 4, 5]

Result: 3

Can anybody suggest how to do this in python?

Upvotes: 1

Views: 77

Answers (3)

Rahul K P
Rahul K P

Reputation: 16081

You can do a different approach. If both numbers equal then both are substrated the value will be zero. So, we can count the value of zero.

NB: This approach will only work for numbers.

In [13]: list(map(int.__sub__, list1, list2)).count(0)
Out[13]: 3

Upvotes: 0

luuk
luuk

Reputation: 1855

You can use a generator expression.

list1 = [1, 2, 3, 4, 5]
list2 = [1, 7, 9, 4, 5]

num_equal = sum(i == j for i, j in zip(list1, list2))
print(num_equal)  # 3

zip(list1, list2) returns an iterator containing tuples of each value in list1 and list2, essentially forming pairs of corresponding items from the two lists:

print(list(zip(list1, list2)))  # [(1, 1), (2, 7), (3, 9), (4, 4), (5, 5)]

You can then check if each pair is equal or not in a list comprehension, creating a list of True or False:

print([i == j for i, j in zip(list1, list2)])  # [True, False, False, True, True]

You can take the sum of this list, as True casts to the integer 1 and False casts to the integer 0. Note that we can use a generator expression instead of a list comprehension (leave out the []) in the sum call to be more memory-efficient.

Upvotes: 5

Have a nice day
Have a nice day

Reputation: 1005

Just loop over both lists and check if the values are the same:

list1 = [1, 2, 3, 4, 5]
list2 = [1, 7, 9, 4, 5]

same = 0
for i in range(len(list1)):  # assuming the lists are the same length
    if list1[i] == list2[i]:
        same += 1

print(same)

Output: 3

Upvotes: 0

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