How to merge every two columns, with pandas, substituting only if the left column value is nan or 0-CodePudding

I have 2n columns and each pair looks like this:

I want to turn each pair of columns into a single one where the 0 or NaN of the left column are substituted by the values on the right column. In this example the result would be

And it is important that this is done for every pair of columns in the dataframe.

CodePudding user response：

try this :

import pandas as pd
import numpy as np
d = {'col1': [1,2,45,44,43,0,0,0,2],
     'col2': [0,0,1,10,22,55,46,75,np.nan],
      }

df = pd.DataFrame(data=d)
df=df.replace(np.nan,0)
df['col2']=np.where(df['col1']==0,df['col2'],df['col1'])

CodePudding user response：

import pandas as pd
import numpy  as np

d = {'col1': [0,0,1,10,22,55,46,34,np.nan],
     'col2': [1,2,45,44,43,0,0,0,2]}

df = pd.DataFrame(d)
df.replace(0, np.nan, inplace=True)
df['col1'].fillna(df['col2']).to_frame()