Try to find the number of times an item appears in another list (of string)-CodePudding

Have this list and another search list number:

animal = ['cat', 'cat', 'dog']
number = ['cat', 'dog']

how do I make in on python so that it calculates the number of times each str inside number can be found in animal? for example, for 'cat' the answer would be 2 and for dog it would be 1. I tried to use the count method for list, but it works only if I have a str, I need it to search it using the list.

I tried to do a for loop (only for the first index):

found = 0
for char in animal:
    if str(number[0]) in str(animal):
        found = found 1
return found

the problem is that I cannot do that if I have an infinite number of str in number! If I have let's say 10 str in number I would have to do that loop for [0],[1],[2],[3],[4],[5],... which can take a lot of time.

CodePudding user response：

you could try this in simple form

list2 = ['cat', 'cat', 'dog']
number = ['cat', 'dog']


print([list2.count(j) for j in number])

output

[2, 1] #2 is times he find the first value 'cat' inside list2

CodePudding user response：

You may want to try this simple Counter:


from collections import Counter

L =  ['cat', 'cat', 'dog']
to_search = ['cat', 'dog']

counts = Counter(L)       # a dictionary - find item is O(1) 
print(counts)


for item in to_search:
    if item in counts:
        print(item, counts[item])

Output:

cat 2
dog 1

If you're only interested in search one single word/animal, you can just do this:

search_word  = 'cat'
print(counts[search_word])    # 2