Pandas: Return Hour from Datetime Column Directly

For posterity: as of 0.15.0, there is a handy .dt accessor you can use to pull such values from a datetime/period series (in the above case, just sales.timestamp.dt.hour!

Assuming timestamp is the index of the data frame, you can just do the following:

hours = sales.index.hour

If you want to add that to your sales data frame, just do:

import pandas as pd
pd.concat([sales, pd.DataFrame(hours, index=sales.index)], axis = 1)

Edit: If you have several columns of datetime objects, it's the same process. If you have a column ['date'] in your data frame, and assuming that 'date' has datetime values, you can access the hour from the 'date' as:

hours = sales['date'].hour

Edit2: If you want to adjust a column in your data frame you have to include dt:

sales['datehour'] = sales['date'].dt.hour