List of the indexes of the cappital letters

Question

i want to return a list of the indexes of the capital letters in a word based on a "user_input" word. i tried the code with lot of words and it actually works except wih "TEsT", it returns [0, 1, 0] instead of [0, 1, 3] :\ What's wrong?

I actually just read the similar question here, the answer was using "enumerate" to get the tuple of (index, char) at the same time, and check if the character is capital case. But i still wanna know what's wrong with my code :)

def capital_indexes(string):
    my_list = list(string)
    one_list = []
    for capital in my_list:
        if capital.isupper():
           capital_index = int(my_list.index(capital))
           one_list.append(capital_index)
    print(one_list)
    #return(one_list)
    
    return (one_list)

#capital_indexes("HeLlO")          

user_input = str(input("Enter a word"))
capital_indexes(user_input)

Just because you call `my_list.index("T")` a second time, it doesn't mean it will find the second "T". — gre_gor, Aug 28 '22 at 11:27
Does this answer your question? [Accessing the index in 'for' loops](https://stackoverflow.com/questions/522563/accessing-the-index-in-for-loops) — TheFungusAmongUs, Aug 28 '22 at 12:15

Ahmed Katary · Answer 1 · 2022-08-28T11:38:52.640

The reason your code returns [0, 1, 0] is because the .index method of a list returns the first instance of the element, so in your example, TEsT has T at index 0 then again at index 3, but int(my_list.index("T")) will always return 0.
Your code will actually always be incorrect for strings with repeated characters,
Ex: AAAA or EVIL EVIL
There are several ways you can solve this, here are two approaches that preserve your code structure

Iterate over the array using its indices rather than elements

 def capital_indexes(string):
     my_list = list(string)
     one_list = []
     for capital_index in range(len(my_list)):
        capital = my_list[capital_index]
        if capital.isupper():
            one_list.append(capital_index)
        print(one_list)

     return (one_list)

Use enumerate to get element and index at the same time

 def capital_indexes(string):
     my_list = list(string)
     one_list = []
     for capital_index, capital in enumerate(my_list):
         if capital.isupper():
             one_list.append(capital_index)
         print(one_list)

     return (one_list)

score 1 · Answer 2 · answered Aug 28 '22 at 11:37

The problem was with .index function. Try this instead:

  def capital_indexes(string):
        strings_list = list(string)
        store_list = []
        for index in range(len(strings_list)):
            if strings_list[index].isupper():
                store_list.append(index)
        print(store_list)
    
    user_input = str(input("Enter a word: "))
    capital_indexes(user_input)

arshovon · Answer 3 · 2022-08-28T11:36:29.157

When you find an uppercase character in the string, you are searching for the first appearance of that character using the index built-in function. That is why you are getting the 0, 1, 0 for TEsT as you can see, the first occurrence of T is found at index 0.

From Python documentation:

list.index(x[, start[, end]])

Return zero-based index in the list of the first item whose value is equal to x. Raises a ValueError if there is no such item.

You can keep an index variable and increase it in the loop. Then when you get an uppercase character, you insert the index in the result list.

def capital_indexes(string):
    one_list = []
    i = 0
    for c in string:
        if c.isupper():
            one_list.append(i)
        i += 1
    return one_list


print(capital_indexes("TEsT"))

Output:

[0, 1, 3]

Alternative solution:

You can use a list comprehension to do the same task:

def capital_indexes(string):
    return [i for i, c in enumerate(string) if c.isupper()]


print(capital_indexes("TEsT"))

References:

Python documentation on data structure

score 0 · Answer 4 · answered Aug 28 '22 at 11:35

We can also use the enumerate class to generate the indices of the iterable object.

def capital_indexes(string):
    one_list = []
    for i, char in enumerate(string):
        if char.isupper():
            one_list.append(i)
    print(one_list)
    return one_list


user_input = str(input("Enter a word"))
capital_indexes(user_input)

Here, i will act as the index of the string as the list, and the char will be the element in the string at index i.

List of the indexes of the cappital letters

4 Answers4

Alternative solution:

References: