Python del if in dictionary in one line

Question

Is there a one line way of doing the below?

myDict = {}
if 'key' in myDic:
    del myDic['key']

thanks

First thing to do with such questions: read the `dict` docs entirely. — Chris Morgan, Feb 21 '12 at 12:04
@user683111: you should accept the answer, if it worked for you :) — avasal, Feb 21 '12 at 12:07
possible duplicate of [How to remove a key from dictionary?](http://stackoverflow.com/questions/11277432/how-to-remove-a-key-from-dictionary) — strongMA, Feb 17 '14 at 19:35

score 22 · Accepted Answer · answered Feb 21 '12 at 12:02

22

You can write

myDict.pop(key, None)

answered Feb 21 '12 at 12:02

Jochen Ritzel

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It should only remove it if 'key' is in myDic (which is different than myDict) – Michel Keijzers Feb 21 '12 at 12:04
1

@MichelKeijzers: Do you really think that is not a typo? – Jochen Ritzel Feb 21 '12 at 12:10
If not, it would be an empty dictionary and trying to remove an item would be useless. – Michel Keijzers Feb 21 '12 at 12:12
yeah it was a impractical example, but it was meant for didactic purposes. It helped – scruffyDog Feb 21 '12 at 12:20

score 4 · Answer 2 · answered Feb 21 '12 at 13:42

Besides the pop method one can always explictly call the __delitem__ method - which does the same as del, but is done as expression rather than as an statement. Since it is an expression, it can be combined with the inline "if" (Python's version of the C ternary operator):

d = {1:2}

d.__delitem__(1) if 1 in d else None

score 0 · Answer 3 · answered Feb 21 '12 at 12:17

0

Would you call this a one liner:

>>> d={1:2}
>>> if 1 in d: del d[1]
... 
>>> d
{}

answered Feb 21 '12 at 12:17

Rusty Rob

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I call it not one line because it's two lines, just scrunched into one in a form not permitted by [PEP 8](http://www.python.org/dev/peps/pep-0008/). Two other reasons I'd never do it this way are (a) it's not as short and pretty; (b) it requires mentioning the dictionary name and the key twice each rather than once. The same arguments apply with `d[k] if k in d else v` versus `d.get(k, v)`. – Chris Morgan Feb 21 '12 at 13:03

Python del if in dictionary in one line

3 Answers3