Append to list if not None, within a list comprehension

Question

I have a dictionary containing some None values under a key, like:

tmp = {"frames": ['0', '12', '56', '35', None, '77', '120', '1000']}

I need to create a list of elements from the dict, under the "frame" key, which are not None (None should be left out). The explicit way is to do:

for frame in tmp['frames']:
    if frame:
        output.append(frame)

But I was wondering if there's a one-liner expression to do the same. I could think of something like:

output = [frame if frame else None for frame in tmp['frames']]

but this way, I don't know how to exclude the None values

what do you want to do with the `None`s? remove them? turn them to a value? leave them in? — Nullman, Mar 10 '22 at 11:17

deadshot · Accepted Answer · 2022-03-10T11:20:27.347

2

You can use if condition in list comprehension

[int(value) for value in tmp['frames'] if value is not None]

edited Mar 10 '22 at 11:20

answered Mar 10 '22 at 11:17

deadshot

what is the value is the result of a function that I don't want to execute twice ? Can i use lambda ? – thanos.a Sep 14 '22 at 09:17
1

you can use walrus operator – deadshot Sep 14 '22 at 10:16

1 Answers1