change datetime 00:00:00 to 24:00:00

Question

I have hourly data which starts from 00 to 23 hour every day. What I am trying to do is to switch 00 to 24 of the prior day for every date.

Here is an example data:

import pandas as pd    

data = {'datetime' : ['19DEC08:22:00:00', '19DEC08:23:00:00', '20DEC08:00:00:00', '20DEC08:01:00:00', '20DEC08:02:00:00'],
         'entry' : ['a','b','c','d','e']}
df = pd.DataFrame(data)

I this example, I want to change '20DEC08:00:00:00' to '19DEC08:24:00:00' and also, I want the same thing to 21Dec08 and 22Dec08 and so on for every 00:00:00.

Is there a pythonic way to do this??

Answer 1

Since DateTime doesn't allow a 24th hour (ie goes from 00:00:00 - 23:59:59), the best way I see to do this is to convert from string to datetime and back to string.

import calendar

def add_24th_hour(row):
    date = row['datetime']
    if date.hour == 00:
        hour = 24
        day = date.day -1
        return "{:02d}{}{:02d}:{:02d}:{:02d}:{:02d}".format(day, 
                                                            calendar.month_abbr[date.month], 
                                                            date.year, 
                                                            hour, 
                                                            date.minute, 
                                                            date.second)
    else:
        return "{:02d}{}{:02d}:{:02d}:{:02d}:{:02d}".format(date.day, 
                                                            calendar.month_abbr[date.month], 
                                                            date.year, 
                                                            date.hour, 
                                                            date.minute, 
                                                            date.second)

df['datetime'] = pd.to_datetime(df['datetime'], format = '%d%b%y:%H:%M:%S')
df.loc[:,'24hr_datetime'] = df.apply(add_24th_hour, axis=1)

I don't see how this would be used in practice but it was interesting to reformat.