CODEWITHSUNDEEP
python
jessiehitech
jessiehitech

Reputation: 25

Printing an index of a list

Hey beautiful community :)

I have this code:

list1 = ['aaaa', 'bbb', 'c', 'ddddd', '', 'ff']

def getLongestStringIndex(list_of_strings):
    longest_string = ""
    for string in list_of_strings:
        if len(string) > len(longest_string):
            longest_string = string
    return longest_string

print(getLongestStringIndex(list1))

I had a task to do it without max function so I dont need to change a lot of the code, but instead of printing the longest string, I need to print the longest string INDEX, so it will return 3

What I need to do to make it done ?

EDIT: I've been asked to do it without .index method and enumerate ..

Thanks in advance :)

Upvotes: 1

Views: 117

Answers (4)

mo1ein
mo1ein

Reputation: 605

I solved that in a short and pythonic way!

>>> strings = ['aaaa', 'bbb', 'c', 'ddddd', '', 'ff']
>>> strings.index(max(strings, key=len))
>>> 3

Upvotes: 3

VoidTwo
VoidTwo

Reputation: 637

One way to do this without the use of max(), list.index(), or enumerate() is by iterating over the entire list and storing the index of the longest string found.

However, we can bypass the entire list iteration by directly finding the longest string and only needing to obtain its index. Assuming of course there are no other restrictions on what to do if more than 1 string is the longest string. Here is an example of how this can be accomplished:

list1 = ['aaaa', 'bbb', 'c', 'ddddd', '', 'ff']

def getLongestStringIndex(list_of_strings):
    longest_string = sorted(list_of_strings, key=len, reverse=True)[0]

    idx: int
    for k in range(len(list_of_strings)):
        if list_of_strings[k] == longest_string:
            idx = k
            break
    return idx

Note: This is especially helpful if the longest string is closer to the beginning of the list since the iteration will be much faster, but if the longest string is near the end or at the end of the list then this method is potentially slower than the initial solution I proposed.

Edit (Better Solution)

A much more Pythonic way to do this is with this one-liner which keeps the list indices "mapped" to the sorted list:

def getLongestStringIndex(list_of_strings):
    return sorted(range(len(list_of_strings)), key=lambda k: len(list_of_strings[k]), reverse=True)[0]

Upvotes: 0

John Gordon
John Gordon

Reputation: 33335

As you're iterating over the string list, keep track of the current position in the list (enumerate is a handy way to do that). When you find a longer string, remember that position.

def getLongestStringIndex(list_of_strings):
    longest_length = 0
    longest_position = 0
    for position,string in enumerate(list_of_strings):
        if len(string) > longest_length:
            longest_length = len(string)
            longest_position = position
    return longest_position

Upvotes: 2

Wojtek TQ
Wojtek TQ

Reputation: 25

In my opinion, you just need a tiny modification.

list1 = ['aaaa', 'bbb', 'c', 'ddddd', '', 'ff']

def getLongestStringIndex(list_of_strings):
    longest_string = ""
    for string in list_of_strings:
        if len(string) > len(longest_string):
            longest_string = string
    return list1.index(longest_string)

print(getLongestStringIndex(list1))

Upvotes: 0

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