how to collapse columns in pandas on null values?

Question

Suppose I have the following dataframe:

pd.DataFrame({\'col1\':    [\"a\", \"a\", np.nan, np.nan, np.nan],
            \'override1\': [\"b\", np.nan, \"b\",          


        

Answer 1

With focus on performance, here's one with NumPy -

In [106]: idx = df.shape[1] - 1 - df.notnull().to_numpy()[:,::-1].argmax(1)

In [107]: pd.Series(df.to_numpy()[np.arange(len(df)),idx])
Out[107]: 
0      c
1      a
2      b
3      c
4    NaN
dtype: object