Pandas: select all dates with specific month and day

Question

I have a dataframe full of dates and I would like to select all dates where the month==12 and the day==25 and add replace the zero in the xmas column with a 1.<

Answer 1

Pandas Series with datetime now behaves differently. See .dt accessor.

This is how it should be done now:

df.loc[(df['date'].dt.day==25) & (cust_df['date'].dt.month==12), 'xmas'] = 1

Answer 2

Basically what you tried won't work as you need to use the & to compare arrays, additionally you need to use parentheses due to operator precedence. On top of this you should use loc to perform the indexing:

df.loc[(df['date'].month==12) & (df['date'].day==25), 'xmas'] = 1