Python: Using split on a string and returning a tuple?

Question

Say I do the following:

>>> a = foo@bar.com
>>> uname, domain = a.split('@')

But what if I only ever want domain, and never uname? For example, if I only ever wanted uname and not domain, I could do this:

>>> uname, = a.split('@')

Is there a better way to split a into a tuple and have it throw away uname?

josh-fuggle · Accepted Answer · 2011-04-21T10:25:33.127

13

To take into account some of the other answers, you have the following options:

If you know that the string will have an '@' symbol in it then you can simply do the following:

>>> domain = a.split('@')[1]

If there is a chance that you don't have an '@' symbol, then one of the following is suggested:

>>> domain = a.partition('@')[2]

Or

try:
    domain = a.split('@')[1]
except IndexError:
    print "Oops! No @ symbols exist!"

edited Apr 21 '11 at 10:25

answered Apr 21 '11 at 10:12

josh-fuggle

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There's a reason why split and partition both exist. Sometimes split is the right thing to use, but this is not one of those times. – John La Rooy Apr 21 '11 at 10:32
Can you please explain when to use split and when to use partition? – john Apr 21 '11 at 21:40

score 6 · Answer 2 · answered Apr 21 '11 at 10:17

6

You could use your own coding style and specify something like "use '_' as don't care for variables whose value you want to ignore". This is a general practice in other languages like Erlang.

Then, you could just do:

uname, _ = a.split('@')

And according to the rules you set out, the value in the _ variable is to be ignored. As long as you consistently apply the rule, you should be OK.

answered Apr 21 '11 at 10:17

João Neves

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This use of `_` is actually quite well established, see [What is the purpose of the single underscore “_” variable in Python?](http://stackoverflow.com/q/5893163/699305). – alexis Mar 14 '17 at 13:09

score 4 · Answer 3 · answered Jul 07 '12 at 00:05

4

This gives you an empty string if there's no @:

    >>> domain = a.partition('@')[2]

If you want to get the original string back when there's no @, use this:

    >>> domain = a.rpartition('@')[2]

answered Jul 07 '12 at 00:05

sjcrowe

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score 4 · Answer 4 · answered Apr 21 '11 at 10:13

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If you know there's always an @ in your string, domain = a.split('@')[1] is the way to go. Otherwise check for it first or add a try..except IndexError block aroudn it.

answered Apr 21 '11 at 10:13

ThiefMaster

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You might also consider `domain = a.partition('@')[2]`. This will set `domain` to `''` if there is no `@` in the string, and will also only split on the first `@` if there is more than one. – Karl Knechtel Apr 21 '11 at 10:16

score 2 · Answer 5 · answered Apr 21 '11 at 10:17

2

This could work:

domain = a[a.index("@") + 1:]

answered Apr 21 '11 at 10:17

Rumple Stiltskin

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Python: Using split on a string and returning a tuple?

5 Answers5