CODEWITHSUNDEEP
pythondictionary
orsettomorbido
orsettomorbido

Reputation: 31

How to delete items from a dictionary

I wanted to know how to delete an element from a dictionary, but I am going directly to my case. For example, I have a dictionary like this one

dic = {(0, 0, 255): [(255, 255, 0), (0, 255, 255)],
       (255, 0, 0): [(0, 0, 255), (0, 255, 0), (255, 255, 0), (0, 255, 255)],
       (0, 255, 0): [(0, 0, 255), (255, 255, 0), (0, 255, 255)],
       (255, 255, 0): [],
       (0, 255, 255): [(255, 255, 0)]}

My purpose is to delete the key that corresponds to the empty list, that here is (255, 255, 0): [] but I would also like to delete the following tuple (i.e. the key) in all other cases where it is present in the dictionary (therefore as a value). So I would like to get to have this:

dic = {(0, 0, 255): [(0, 255, 255)],
       (255, 0, 0): [(0, 0, 255), (0, 255, 0), (0, 255, 255)],
       (0, 255, 0): [(0, 0, 255), (0, 255, 255)],
       (0, 255, 255): []}

I want to specify the fact that I save each deleted key in a list, in fact I used this to be able to delete from the dictionary every key that had an empty list as a value, but I cannot then take the deleted value and delete it from the whole dictionary How can I do this?

Upvotes: 1

Views: 96

Answers (3)

Nestor
Nestor

Reputation: 559

To delete a key-value pair from a dictionary just del dictionary[key]

Updated:

In your case:

dic = {(0, 0, 255): [(255, 255, 0), (0, 255, 255)],
   (255, 0, 0): [(0, 0, 255), (0, 255, 0), (255, 255, 0), (0, 255, 255)],
   (0, 255, 0): [(0, 0, 255), (255, 255, 0), (0, 255, 255)],
   (255, 255, 0): [],
   (0, 255, 255): [(255, 255, 0)]}


if __name__ == '__main__':
    to_delete = []
    for key, value in dict(dic).items():
        if len(value) == 0:
            to_delete.append(key)
            del dic[key]

    for key in dict(dic):
        dic[key] = [item for item in dic[key] if item not in to_delete]

    print(dic)

Output:

{
    (0, 0, 255): [(0, 255, 255)], 
    (255, 0, 0): [(0, 0, 255), (0, 255, 0), (0, 255, 255)], 
    (0, 255, 0): [(0, 0, 255), (0, 255, 255)], 
    (0, 255, 255): []
}

Upvotes: 2

mujjiga
mujjiga

Reputation: 16856

to_del = [k for k, v in dic.items() if len(v) == 0]
_ = [dic.pop(k) for k in to_del]
_ = [dic[k].remove(d) for k in dic.keys() for d in to_del if d in dic[k]]
print (dic)

Output:

{(0, 0, 255): [(0, 255, 255)],
 (255, 0, 0): [(0, 0, 255), (0, 255, 0), (0, 255, 255)],
 (0, 255, 0): [(0, 0, 255), (0, 255, 255)],
 (0, 255, 255): []}

Upvotes: 0

Kebby
Kebby

Reputation: 329

You can do something like this:

list1 = [k for k, v in dic.items() if v == []]
newDict1 = {k: v for k, v in dic.items() if v != []}
newDict2 = {k: v for k, v in newDict1.items() if not any(xs in v for xs in list1)}

Explanation of the code:

  1. list1 will keep a copy of all the blank arrays in dic
  2. newDict1 will eliminate all the blank arrays from dic and save a copy
  3. newDict2 will check all the remaining tuples and eliminate any tuple which contains the deleted keys as values.

Upvotes: 2

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