CODEWITHSUNDEEP
pythondictionary-comprehension
montoisky
montoisky

Reputation: 177

Dictionary comprehension with list.extend applied to each value

I want to replace the following for loop into a one-liner dict comprehension

my_dict={'i':([3,4,5,6]), 'j':[10,20,30,40]}

for key, value in my_dict.items():
    zeros=[0]*2  
    zeros.extend(value)
    my_dict[key] = zeros

into:

{key:([0]*2).extend(value) for key, value in my_dict.items()}

However that does not seem to work. I have also tried:

{key:value.insert(0, [0,0]) for key, value in my_dict.items()}

without success.

Desired output is

{'i': [0, 0, 3, 4, 5, 6], 'j': [0, 0, 10, 20, 30, 40]}

Upvotes: -2

Views: 101

Answers (1)

Jab
Jab

Reputation: 27515

list.extend and list.insert both return None. What you could do is just append the values list to a list of zero's:

{key: [0, 0] + value for key, value in my_dict.items()}

Upvotes: 2

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