python - Extracting the data frame of last 30 days from the last available date in the data frame

Question

I see that finding the last 30 days of the dataframe by

import datetime
days30=df[df.Date > datetime.datetime.now() - pd.to_timedelta("30day")]

This gives last 30 days considering today's date. But I am interested in getting the last 30 days that is available in the dataframe. So tried this method

lastdayfrom = df['Date'].max()
days30 = df.loc[lastdayfrom - pd.Timedelta(days=30):lastdayfrom].reset_index()

This threw error message -TypeError: '<' not supported between instances of 'int' and 'Timestamp' How do I get the last date to use in filtering the last available date with out making date as index if possible?

Answer 1

lastdayfrom = df['Date'].max()
critDate = lastdayfrom - pd.Timedelta(days=30)
days30 = df.loc[df.Date > critDate]

should work