CODEWITHSUNDEEP
pythondictionary
ustroetz
ustroetz

Reputation: 6312

How to remove a list value from a dictionary?

Given a dictionary with lists as values.

myDict = {0: [0, 1, 2], 1: [], 2: [20, 25, 26, 28, 31, 34], 3: [], 4: [0, 1, 2, 3, 4, 7, 10], 5: [], 6: [10, 20, 24]}

How can I remove items from the dictionary if the value list is empty?

I tried to iterate over the dictionary and remove items, but the dictionary size is not allowed to change during iteration.

for item in myDict:
    if myDict[item] == []:
        print item
        del myDict[item]

Upvotes: 3

Views: 177

Answers (2)

Schechter
Schechter

Reputation: 223

for k in myDict.keys():
  if myDict[k] == []:
    del myDict[k]

This will remove any key for which the value is and empty array.

Upvotes: 0

falsetru
falsetru

Reputation: 369424

Using dict comprehension:

>>> myDict = {0: [0, 1, 2], 1: [], 2: [20, 25, 26, 28, 31, 34], 3: [], 4: [0, 1, 2, 3, 4, 7, 10], 5: [], 6: [10, 20, 24]}
>>> myDict = {k: v for k, v in myDict.items() if v}
>>> myDict
{0: [0, 1, 2], 2: [20, 25, 26, 28, 31, 34], 4: [0, 1, 2, 3, 4, 7, 10], 6: [10, 20, 24]}

Adding, deleting dictionary entries are not allowed while iterating it. Make a copy of keys to overcome it. For example, in the following, I used tuple(myDict) to get copy of the keys.

>>> myDict =  {0: [0, 1, 2], 1: [], 2: [20, 25, 26, 28, 31, 34], 3: [], 4: [0, 1, 2, 3, 4, 7, 10], 5: [], 6: [10, 20, 24]}
>>> for item in tuple(myDict):
...     if myDict[item] == []:
...         del myDict[item]
...
>>> myDict
{0: [0, 1, 2], 2: [20, 25, 26, 28, 31, 34], 4: [0, 1, 2, 3, 4, 7, 10], 6: [10, 20, 24]}

Upvotes: 5

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