Nested list Comparision with format string in python

Question

l = ["Youtube", "Instagram", "Facebook"]

a = [
    [
        "{} {}".format(i[2 * j : 2 * j + 1], i[2 * j + 1 : 2 * j + 2])
        for j in range(len(i) // 2)
    ]
    for i in l
]
print(a)

This will return

[['Y o', 'u t', 'u b'], ['I n', 's t', 'a g', 'r a'], ['F a', 'c e', 'b o', 'o k']]

How the above list I can join first character space with the second character, Please tell if i missing anything in the inner array List.

Below is the output I want the odd space with even character

[['Yuu otb'], ['Isar ntga'], ['Fcbo aeok']]

And you want to discard any final odd letter, correct? I.e. the "e" in "Youtube" and the "m" in "Instagram"? — Tom Karzes
– Tom Karzes, Commented Oct 1, 2019 at 12:47
What have you tried so far? You have pretty good code in here, you don't need to join the elements, just modify how the inner part works. — h4z3
– h4z3, Commented Oct 1, 2019 at 12:48

yatu · Accepted Answer · 2019-10-01 12:58:08Z

4

You could join slices of the strings as follows:

[[' '.join((s[:-1:2], s[1::2]))] for s in l]
# [['Yuu otb'], ['Isar ntga'], ['Fcbo aeok']]

answered Oct 1, 2019 at 12:58

yatu

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3 Comments

Scott Hunter Over a year ago

Slickest solution so far (IMHO).

sarvesh kumar Over a year ago

@yatu, you are a man, how you think in that way one-liner solution, I really appreciate your solution thanks!

sarvesh kumar Over a year ago

@yatu the first slice should be s[::2] because it will go untill the end of the string, it fails for l = ["ivvkxq", "ivvkx"], So please edit your awswer

James · Accepted Answer · 2019-10-01 12:49:48Z

1

You don't actually need a double list comp for this. You can accomplish this by slicing up to the last even element and stepping by 2.

If you want them as single strings in a one-deep list:

[f'{x[:2*(len(x)//2):2]} {x[1:2*(len(x)//2):2]}' for x in l]
# returns:
['Yuu otb', 'Isar ntga', 'Fcbo aeok']

If you want them 2-deep:

[[f'{x[:2*(len(x)//2):2]} {x[1:2*(len(x)//2):2]}'] for x in l]
# returns:
[['Yuu otb'], ['Isar ntga'], ['Fcbo aeok']]

answered Oct 1, 2019 at 12:49

James

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Comments

Scott Hunter · Accepted Answer · 2019-10-01 12:51:07Z

0

Sticking with the main structure of your original solution,

a = [
    [
        "{} {}".format("".join([i[2 * j : 2 * j + 1] for j in range(len(i) // 2)]),
            "".join([i[2 * j + 1 : 2 * j + 2] for j in range(len(i) // 2)]))
    ]
    for i in l
]

answered Oct 1, 2019 at 12:51

Scott Hunter

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2 Comments

sarvesh kumar Over a year ago

Scott Hunterr, I agree with your solution will give desire output, but this seems to be take high time complexity as there are 3*for loop

Scott Hunter Over a year ago

Time is comparable to your original code; additional loop isn't nested. Your code did 2 expressions for each j; mine does 1 expression for each j, twice.

Celius Stingher · Accepted Answer · 2019-10-01 12:54:22Z

0

I have combined zip and join

l = ["Youtube", "Instagram", "Facebook"]
a = [["{} {}".format(i[2 * j : 2 * j + 1], i[2 * j + 1 : 2 * j + 2])for j in range(len(i) // 2)]for i in l]
b = [[''.join(x) for x in zip(*i) if ''.join(x).replace(' ', '')] for i in a]
c = [' '.join(i) for i in b]
print(c)

Output:

['Yuu otb', 'Isar ntga', 'Fcbo aeok']

answered Oct 1, 2019 at 12:54

Celius Stingher

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