[FIXED] replacing values in pandas df column with values from another of same row if condition is met

Issue

I've got a df that I'm trying to clean. In instances where the value in col1 is = 0 I want to replace the 0 with the corresponding value from col2. What's the easiest way to do this?

edit: I got it nevermind..

Solution

One way is to use:

df['col1'] = df['col1'].replace(0, np.nan).fillna(df['col2'])

Another way with mask:

df['col1'] = df['col1'].mask(df['col1'] == 0, other=df['col2'])

Or the opposite with where:

df['col1'] = df['col1'].where(df['col1'] != 0, other=df['col2'])

And with loc:

df.loc[df['col1'].eq(0), 'col1'] = df['col2']

Answered By - Corralien