pythonic way to split string into two lists

Question

I have a lot of files with string pairs looking like:

first_string~second_string

The first part is what to change and the second, to what change the first part.

These are regular expressions and I run my app with these collections to apply all modifications to dirty tv schedule listings for more than a hundred channels. I did it before with C# but now I am reworking it in Python.

Let's imagine I have a text file with many strings each on its own line that look like find_this~change_to_this. I need to get two lists. First will contain all find strings and the second will contain all change strings.

Let's imagine, I have 120 such pairs. Now I divide these pairs into two lists, each has size of 120 items. One has finds, the other - changes. Now I can get both strings by some index, for example, 57, and it will give me 57th item from both lists, so I get a right change string for any find string. I found some variants, but not sure which one is better.

What is the pythonic to split a collection of strings like this:

first_string~second_string

Using that input to split it into two lists where first list contains items before ~ and the second one - after.

"better"? Faster? Cheaper? Most like Ruby? What do you mean by "Better"? "beautiful" is subjective. "consistent" with what? Are you using partition? — S.Lott
– S.Lott, Commented Apr 18, 2011 at 17:47
Ok, sorry for the subjective requirements. Let's call it pythonic. Does it make any sense now? :) — Sergei Basharov
– Sergei Basharov, Commented Apr 18, 2011 at 17:48
Not really. Your first_string~second_string example seems incomplete. Further, you haven't shown the code you're already using. This is just partition and split. Please include your solution so we can comment on it. — S.Lott
– S.Lott, Commented Apr 18, 2011 at 17:50
solution to what? What does this mean? "Surely, they need to be in the same positions in the lists. So that when I I want to get 6th item from the first list, I get the same position item from the second list as they were in original string"? Can you please update the question to explain what that means? Others may benefit from this question. It would help if the question were more clear. — S.Lott
– S.Lott, Commented Apr 18, 2011 at 19:14

Sven Marnach · Accepted Answer · 2011-04-18 17:48:56Z

13

x = ["c~d", "e~f", "g~h"]
a, b = zip(*(s.split("~") for s in x))
print a
print b

prints

('c', 'e', 'g')
('d', 'f', 'h')

answered Apr 18, 2011 at 17:48

Sven Marnach

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2 Comments

Nagabhushan S N Over a year ago

How to get them (a, b) as lists instead of tuples? I tried zip(*[s.split("~") for s in x]), but it still returns them as tuple

Sven Marnach Over a year ago

@NagabhushanSN a, b = map(list, zip(*(s.split("~") for s in x)))

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