adding keys to dict if condition is met, otherwise skip key if False

Asked Oct 07 '17 at 21:23

Active Oct 07 '17 at 21:30

Viewed 893 times

Is there a pythonic way to add a key to a dictionary if the condition is True, and just completely ignore it (skip) if it is false?

dict = {}

frame = scatter[x > y]
if frame.empty == False:
    dict[pct] = frame
else:
    None

I've tried writing:

dict[pct] = frame if frame.empty == False else None

But the problem here is that the "else None" adds a "None" value to the dictionary , and I need it to completely ignore/skip (not do anything) if else is activated.

asked Oct 07 '17 at 21:23

thomas.mac

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4

Just remove the `else: None` part from the first code – vaultah Oct 07 '17 at 21:23
1

but then I can't write it in 1 line , dict[pct] = frame if frame.empty == False raises an error – thomas.mac Oct 07 '17 at 21:25
1

Note also that `x == False` is better written as `not x`. – Izaak van Dongen Oct 07 '17 at 21:25
1

shouldn't just: **if frame:** work? – Anton vBR Oct 07 '17 at 21:26
2

@thomas.mac Just write it in two lines. You can't use a ternary operator because it just fundamentally has to evaluate to something. Having an extra line of code isn't a disaster. – Izaak van Dongen Oct 07 '17 at 21:27
@thomas.mac why must you write it on 1 line? – juanpa.arrivillaga Oct 07 '17 at 21:34
was just trying to write shorter / cleaner code, but I think I'll just remove the else statement – thomas.mac Oct 07 '17 at 21:36
1

Shorter and cleaner are often very different goals IMHO. – miradulo Oct 07 '17 at 21:38
1

cleaner != shorter – juanpa.arrivillaga Oct 07 '17 at 21:40
`frame.empty and dct.__setitem__(pct, frame)` is one non-pythonic way but I am just putting it here to make its relationship with the duplicate clearer. – ayhan Oct 07 '17 at 21:42
@ayhan Wouldn't that be `not frame.empty`? – miradulo Oct 07 '17 at 21:44
1

@Mitch Yes, my mistake. Thanks. – ayhan Oct 07 '17 at 21:46

adding keys to dict if condition is met, otherwise skip key if False

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