python - Creating a new column in a pandas csv file through conditions -

i've searched thoroughly hours answer this, unfortunately haven't been able find anything.

i have csv file looks on picture.

what want is, example, create new column every row 0, except if month==1 and day>11. did similar, made new column rows=0 when hour>8 , hour<20, , rest ones:

datatest['day_or_night'] = 0  datatest['day_or_night'][datatest['hour'] < 8] = 1  datatest['day_or_night'][datatest['hour'] > 20] = 1 

any appreciated!

try this:

df['new'] = np.where((df.month==1) & (df.day>11), 1 0)