If statement in expression / virtual column

[abf7d]

I want to set a virtual column to a calculation using another column in Vaex. I need to use an if statement inside this calculation. In general I want to call

df['calculation_col'] = log(df['original_col']) if df['original_col'] == 0 else -4

I then try to run the count function in Vaex:

hist = df.count(
        binby='calculation_col',
        limits=limits,
        shape=binnum,
        delay=True
    )

When I try to execute this code I get the error ValueError: zero-size array to reduction operation minimum which has no identity.

How can I use a conditional for a virtual column in Vaex?

[maartenbreddels]

Hi,

debug tip: If you print this out (in the repr) you'll probably see what is evaluates into

df['original_col']) if df['original_col'] == 0 else -4

you can use where instead:

(df['original_col']) == 0).where(df['original_col'], -4)

Hope that helps

cheers,

Maarten

[abf7d]

This worked! Thank you so much!