df2 = pd.DataFrame({'A': np.random.randn(8), 'B': pd.date_range('1/1/2011',
    periods=8, freq='H'), 'C': np.random.randn(8)})
df2[['D', 'E']] = df2.apply(function, axis=1)
df2
Pandas apply with list output gives ValueError once df contains timeseries