date      people_count
0   30/03/17  6

1   31/03/17  4

2   1/04/17   7

3   2/04/17   9

date      people_count   weekend
0   30/03/17  6              0

1   31/03/17  4              0

2   1/04/17   7              1

3   2/04/17   9              1

df = pd.read_csv('myfile.csv', encoding = 'ISO-8859-1')

df['weekend'] = pd.DatetimeIndex(df['date']).dayofweek

if pd.DatetimeIndex(df['date']).dayofweek in (5, 6):
    df['weekend'] = 1
else:
    df['weekend'] = 0