如何计算一个列表中一个数字重复多少次（以及是否基于另一个列表中的值不使用一个数字）？

Question

I have two lists :

list1 = [1,2,3]
list2= [1,1,2,2,2]

Is there a way to print how many times a number in list1 has occurred in list2/ or if a number hasn't appeared in the list2, then say 0.

i tried using:

Counter(list2)

but this gives me the output:

{2: 3, 1: 2}

the outcome I want is:

{1: 2, 2: 3, 3:0}

When I use counter it doesn't say how many 3's are seen in list2. is there a simple way around this problem?

Answer 1

You need to iterate list1 and then give reference to list2

>>> {i: list2.count(i) for i in list1}
{1: 2, 2: 3, 3: 0}

Answer 2

Use simple for loop

list1 = [1,2,3]
list2= [1,1,2,2,2]

dict = {}
count = 0
for num1 in list1:
   for num2 in list2:
      if num1 == num2:
        count = count +1
   dict[num1] = count
   count = 0


print(dict)

output

{1: 2, 2: 3, 3:0}