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Felipe Gorcóa
Felipe Gorcóa

Reputation: 39

Creating lists from a list of strings without list comprehension

I have a list m:

m = ['Apple', 'Lemon', 'Orange']

and I want output as follows:

['Apple'], ['Lemon'], ['Orange']

How can this be done without using list comprehension and for cycles?

In my approach I dont understand what variables to use. Any ideas?

def lists(m):    
    count=0`
    while count < len(m):            
        len(m)
        count += 1
        
    return #separated lists?

print(lists(m))

Upvotes: 0

Views: 327

Answers (4)

Alain T.
Alain T.

Reputation: 42143

you could use recursion and parameter unpacking

def makeLists(first,*rest): 
    return [[first]] + (makeLists(*rest) if rest else [])

m = ['Apple', 'Lemon', 'Orange']

print(makeLists(*m))

# [['Apple'], ['Lemon'], ['Orange']]

You can also make it without parameter unpacking:

def makeLists(strings): 
    return ([strings[:1]] + makeLists(strings[1:])) if strings else []

m = ['Apple', 'Lemon', 'Orange']

print(makeLists(m))

# [['Apple'], ['Lemon'], ['Orange']]

Upvotes: 0

superb rain
superb rain

Reputation: 5520

No list comprehension, presumably no "for cycles" (might depend on what you mean), and results in a tuple as requested.

>>> *map(lambda s: [s], m),
(['Apple'], ['Lemon'], ['Orange'])

Upvotes: 0

costaparas
costaparas

Reputation: 5237

Here's a traditional while loop approach. Details of how it works are in the comments.

m = ['Apple', 'Lemon', 'Orange']

def list_to_lists(lst):
    i = 0

    # this will be the result list, containing lists of strings
    res = []

    while i < len(lst):

        # [lst[i]] creates a new list containing the i'th element of lst
        # res.append will append this to the result list
        res.append([lst[i]])

        i += 1

    # return the result list
    return res

lists = list_to_lists(m)
print(lists)

Its been an incredibly long time since I've actually written a while loop. Do note that for loops are often neater for this sort of thing - see @daniel-hao's example.

Upvotes: 0

Daniel Hao
Daniel Hao

Reputation: 4980

Since you have asked to avoid List Comprehension, you could try something like this: (BTW, while is just kind of for loop!)

m = ['Apple', 'Lemon', 'Orange']

from typing import List

def split_list(lst: List[str]):
    
    res = []
    
    for item  in lst:
        res.append([item])

    return res


print(split_list(m))

Upvotes: 1

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