python - How to change the time of a pandas datetime object to the start of the hour?

Question

I have a pandas Dataframe in which one of the column is pandas datetime column created using pd.to_datetime()1. I want to extract the date and hour from each datetime object, in other words, I want to change the minute and seconds to 0.

I used normalize() to change the time to midnight but don't how how to change the time to start of the hour. Please suggest a way to do so.

Answer 1

making some test data and turning it into a dataframe

rng = pd.date_range('1/1/2018 11:59:00', periods=3, freq='min')
df = pd.DataFrame(rng)
print(df)
print(df[0].round('H'))

gives the input

                    0
0 2018-01-01 11:59:00
1 2018-01-01 12:00:00
2 2018-01-01 12:01:00

and rounded to the nearest hour gives

                      0
0   2018-01-01 12:00:00
1   2018-01-01 12:00:00
2   2018-01-01 12:00:00

and

print(df[0].dt.floor('H'))

gives

                      0
0   2018-01-01 11:00:00
1   2018-01-01 12:00:00
2   2018-01-01 12:00:00

if you always want to round down. Likewise, ceil('H') if you want to round up