python 2.7 : remove a key from a dictionary by part of key

Question

I have a python dictionary , the dictionary key composed from tupples,

like this :

{
 (u'A_String_0', u'A_String_1', u'B_String_3', u'Remove_Me'): 300, 
 (u'A_String_0', u'B_String_4'): 301, 
 (u'A_String_0', u'A_String_1', u'B_String_3', u'Remove_Key'): 301,
}

I'd like to remove all keys from dictionary when only part of tupple appears in key :

for example 'Remove_'

In this case , must pop two keys: one contains u'Remove_Me' and another contains u'Remove_Key'

Finally the dictionary will look like this :

{
  (u'A_String_0', u'B_String_4'): 301
}

Thanks a lot !

Possible duplicate of [filter items in a python dictionary where keys contain a specific string](http://stackoverflow.com/questions/23862406/filter-items-in-a-python-dictionary-where-keys-contain-a-specific-string) — Eugene Soldatov, Dec 22 '15 at 15:23

Iron Fist · Accepted Answer · 2015-12-22T12:38:38.193

7

One way:

    >>> d = {
     (u'A_String_0', u'A_String_1', u'B_String_3', u'Remove_Me'): 300, 
     (u'A_String_0', u'B_String_4'): 301, 
     (u'A_String_0', u'A_String_1', u'B_String_3', u'Remove_Key'): 301,
    }
    >>> 
    >>> 
    >>> d_out = {k:v for k,v in d.items() if not any(x.startswith('Remove_') for x in k)}
    >>> d_out
{(u'A_String_0', u'B_String_4'): 301}

EDIT: In case you wanted to check if Remove_ is part of any item of the tuple key, then you are better with:

>>> d_out = {k:v for k,v in d.items() if not any('Remove_' in x for x in k)}

edited Dec 22 '15 at 12:38

answered Dec 22 '15 at 12:28

Iron Fist

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or `{i:j for i,j in d.items() if not any('Remove_' in x for x in i)}` – Avinash Raj Dec 22 '15 at 12:30
Thanks @AvinashRaj for the head's up – Iron Fist Dec 22 '15 at 12:32
1

Don’t use this if there may be elements `DontRemove_Me` inside the key ;) – poke Dec 22 '15 at 12:32
@poke op says "only part of the tuple appears in key", not about startswith. – Avinash Raj Dec 22 '15 at 12:36
@AvinashRaj That could refer to the string being anywhere within the tuple key, or that substring being anywhere within a particular string. Not completely clear, so it’s probably best to just mention the impact of one solution over another :) – poke Dec 22 '15 at 12:38
I would like to know why this has been down voted...please comment – Iron Fist Dec 22 '15 at 17:54

score 5 · Answer 2 · answered Dec 22 '15 at 12:30

Since keys are always a combined thing without any structure or pattern, you always need to have the full key in order to access elements in the dictionary. In particular this means that you cannot find elements using some partial key. So in order to do this, there is no way other than looking at all keys:

>>> d = {
 (u'A_String_0', u'A_String_1', u'B_String_3', u'Remove_Me'): 300, 
 (u'A_String_0', u'B_String_4'): 301, 
 (u'A_String_0', u'A_String_1', u'B_String_3', u'Remove_Key'): 301}
>>> { k: v for k, v in d.items() if not any(x.startswith('Remove_') for x in k) }
{(u'A_String_0', u'B_String_4'): 301}

This will create a new dictionary from the source dictionary, taking every key k for which any(x.startswith('Remove_') for x in k) is not true. That any() expression will be true if there is an element in x that starts with 'Remove_'.

score 2 · Answer 3 · answered Dec 22 '15 at 12:35

Using the same dictionnary, not a one-liner though. Also note that original post said "part of tupple appears in key" so it hasn't to be in the beginning i.e startswith()

>>> d = {
...      (u'A_String_0', u'A_String_1', u'B_String_3', u'Remove_Me'): 300, 
...      (u'A_String_0', u'B_String_4'): 301, 
...      (u'A_String_0', u'A_String_1', u'B_String_3', u'Remove_Key'): 301,
...     }
>>> for k in d.keys():
...     for i in k:
...         if 'Remove_' in i:
...             del d[k]
...             break
... 
>>> d
{(u'A_String_0', u'B_String_4'): 301}

score 2 · Answer 4 · answered Dec 22 '15 at 12:38

if it is sartswith you have already got your answer. If not then you could use in or re for more complex checking

Code:

import re
dic = {
 (u'A_String_0', u'A_String_1', u'B_String_3', u'Remove_Me'): 300, 
 (u'A_String_0', u'B_String_4'): 301, 
 (u'A_String_0', u'A_String_1', u'B_String_3', u'Remove_Key'): 301,
}
print {k:v for k,v in dic.items() if not any(re.match("Remove", val)for val in k)} # Using in
print {k:v for k,v in dic.items() if not any("Remove" in val for val in k)} # Using re.match

Output:

{(u'A_String_0', u'B_String_4'): 301}

Note:

This would remover the key if Remove occurs any where in the key

python 2.7 : remove a key from a dictionary by part of key

4 Answers4