Pandas - Append Column With Sum Of Row Values (if Sum Is Even), Or Nan (if Odd)

I have a dataframe and I want a new column t with sum of other columns in the same row. Criteria is I want NaN if the sum is odd, and the sum if the value is even. df = pd.DataFram

Solution 1:

Using np.where:

df['new'] = np.where(df.sum(1)%2==0, df.sum(1), np.nan)

df
   p  q  r  s   new
0  1  8  7  2  18.0
1  8  5  9  4  26.0
2  1 -5  3 -2   NaN