Why do I keep getting a “list indices must be integers or slices, not str”?

Question

I keep getting a "list indices must be integers or slices, not str" when I run this function, and Im not sure why. This function takes an equation and splits it by number and operator ie: 1+8-9 = ['1','+','8','-','9']

def trimFunction(p):
    list = re.split("([+ -])", p)
    if list[0] == '':
        list.remove('')
        
    counter = 0
    for x in list:
#the error happens here vvvv
        if list[x].isnumeric(): 
            counter += 1
    return list, counter 

Answer 1

Because you are iterating over each item in a list which is a string.

x in your loop for x in list with given ['1','+','8','-','9'] is '1', '+', '8', '-', '9', not the index of them (0, 1, 2, 3, 4).

So your loop should be:

for x in list:
    if x.isnumeric():
        counter += 1
return list, counter

or

for index in range(len(list)):
    if list[index].isnumeric():
        counter += 1
return list, counter

Answer 2

You need to x.isnumeric() inplace of list[x].isnumeric()

import re
def trimFunction(p):
    list = re.split("([+ -])", p)
    print(list)
    if list[0] == '':
        list.remove('')
    counter = 0
    for x in list:
#Correction
        if x.isnumeric(): 
            counter += 1
    return list, counter 
trimFunction('1+8-9')

OUTPUT (['1', '+', '8', '-', '9'], 3)