Round pandas datetime index?

Question

I am reading multiple spreadsheets of timeseries into a pandas dataFrame and concatenating them together with a common pandas datetime index. The datalogger that logged the

Answer 1

For data columns; Use: round_hour(df.Start_time)

def round_hour(x,tt=''):
    if tt=='M':
        return pd.to_datetime(((x.astype('i8')/(1e9*60)).round()*1e9*60).astype(np.int64))
    elif tt=='H':
        return pd.to_datetime(((x.astype('i8')/(1e9*60*60)).round()*1e9*60*60).astype(np.int64))
    else:   
        return pd.to_datetime(((x.astype('i8')/(1e9)).round()*1e9).astype(np.int64))