find function in python list code example

Example 1: python find in list

# There is several possible ways if "finding" things in lists.
'Checking if something is inside'
3 in [1, 2, 3] # => True
'Filtering a collection'
matches = [x for x in lst if fulfills_some_condition(x)]
matches = filter(fulfills_some_condition, lst)
matches = (x for x in lst if x > 6)
'Finding the first occurrence'
next(x for x in lst if ...)
next((x for x in lst if ...), [default value])
'Finding the location of an item'
[1,2,3].index(2) # => 1
[1,2,3,2].index(2) # => 1
[1,2,3].index(4) # => ValueError
[i for i,x in enumerate([1,2,3,2]) if x==2] # => [1, 3]

Example 2: find in python

def find_all_indexes(input_str, search_str):
    l1 = []
    length = len(input_str)
    index = 0
    while index < length:
        i = input_str.find(search_str, index)
        if i == -1:
            return l1
        l1.append(i)
        index = i + 1
    return l1


s = 'abaacdaa12aa2'
print(find_all_indexes(s, 'a'))
print(find_all_indexes(s, 'aa'))