Split the first item of a python list using whitespace

Question

I have a simple list as below:

lst = ['11 12221/n']

I want to split the first item into a list as below:

['11', '12221']

This seems relatively simple to me but I cant get it to work. My first approach was to do:

lst[0].split()

but when I print list no changes have occurred. I therefore tried:

newLst=[]

for x in lst:
    newList.append(x.split())

But from this I get

[['11', '12221\n']]

I think I must fundamentally be misunderstanding list comprehension, could someone explain why my code didnt work and how it should be done?

Thank you

It seems that you need to use "extend" instead of "append". See [here][1] [1]: http://stackoverflow.com/questions/252703/python-append-vs-extend — Avision, Apr 19 '14 at 14:51

score 5 · Answer 1 · 2014-04-19T15:04:20.760

5

I believe you are looking for this:

>>> lst = ['11 12221\n']
>>> # Split on spaces explicitly so that the \n is preserved
>>> lst[0].split(" ")
['11', '12221\n']
>>> # Reassign lst to the list returned by lst[0].split(" ")
>>> lst = lst[0].split(" ")
>>> lst
['11', '12221\n']
>>>

edited Apr 19 '14 at 15:04

answered Apr 19 '14 at 14:51

I think it originally was lst anyway… – Quintec Apr 19 '14 at 15:02
@thecoder16 - No, the OP changed it. It used to be `list`. Let me edit my answer. – Apr 19 '14 at 15:04
Okay. I can’t see a “edited x secs ago” link though… – Quintec Apr 19 '14 at 15:05
@thecoder16 - He edited his question within the 5-minute grace period given after posting. Thus, the changes to the post will not be recorded in the edit history. – Apr 19 '14 at 15:07
@thecoder16, iCodez is right. It __did__ used to be `list` in the OP's question. – sshashank124 Apr 19 '14 at 15:07
@sshashank124 Okay, I am just asking! – Quintec Apr 19 '14 at 15:11

score 2 · Answer 2 · answered Apr 19 '14 at 14:49

2

Use a list comprehension:

[part for entry in origlist for part in entry.split(None, 1)]

This allows for multiple strings and splits just once (so only two elements are ever created for each string).

answered Apr 19 '14 at 14:49

Martijn Pieters

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score 2 · Accepted Answer · answered Apr 19 '14 at 14:49

2

You can do it as:

lst = ['11 12221\n']

lst = lst[0].split()

list[0] gets you '11 12221\n' which you then split() and assign back to lst giving you:

['11', '12221\n']

You have to assign the split back to the variable

Note: You should not name your variables as ony of the python reserved words. Use perhaps lst instead.

If you only want to split at a space, do: split(' ') instead.

Demo: http://repl.it/R8w

answered Apr 19 '14 at 14:49

sshashank124

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1

`lst[0].split()` will *remove* the trailing `\n` newline, so the output will be `['11', '12221']`. – Martijn Pieters Apr 19 '14 at 15:15
@PaulBarr This code doesn't do what you claim to want. If this answer fixes your problem you should edit the question to reflect that. – juanchopanza Apr 19 '14 at 15:19
@juanchopanza what result would my question want literally? I have probably misused the term whitespace – PaulBarr Apr 19 '14 at 15:31
@PaulBarr You claim you want this: `['11', '12221\n']`. The code above gives `['11', '12221']`. – juanchopanza Apr 19 '14 at 15:32
1

@juanchopanza ok, I meant to split ['11 12221\n'] into ['11', '12221'], what would the correct terminology be for this? – PaulBarr Apr 19 '14 at 15:34
@PaulBarr Just fix your answer so that it asks for what you actually want. – juanchopanza Apr 19 '14 at 15:35

juanchopanza · Answer 4 · 2014-04-19T16:19:50.940

1

You need to assign the result of the call to std.split to something:

>>> my_list = ['11 12221\n']     # do not name a variable after a std lib type
>>> my_list = my_list[0].split()
>>> print my_list
['11', '12221']

The main issue is that the call to str.split returns a list of strings. You were just discarding the result.

edited Apr 19 '14 at 16:19

answered Apr 19 '14 at 14:50

juanchopanza

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Split the first item of a python list using whitespace

4 Answers4