Python: Working with DateTimes

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In this tutorial I will show you the different ways of working with dates and times in python. Which includes working with milliseconds. You should note this isn’t all available options just some that I have encountered over the years.

Install Python Packages:

Open cmd/terminal and if required navigate to your sites working folder. (note: if you are working in a virtual env you should ensure you source it first).

  1. pip install python-dateutil

There are many different packages that we can use to work with date and times. You need to decide what is right for you.

dateutil:

The following will convert the date string you give it fast and easily. This gives you back the datetime object. Notice how we don’t need to pass it a date time format. To me this is very convenient.

  1. from dateutil import parser
  2.  
  3. date_str = '2017-06-06'
  4. date_time_str = '2017-06-07 12:34'
  5. date_time_str_2 = '2017-06-07 12:34:46'
  6. date_time_str_3 = '2017-06-07 12:34:42.234'
  7.  
  8. result = parser.parse(date_str)
  9. print(result) #2017-06-06 00:00:00
  10. result = parser.parse(date_time_str)
  11. print(result) #2017-06-07 12:34:00
  12. result = parser.parse(date_time_str_2)
  13. print(result) #2017-06-07 12:34:46
  14. result = parser.parse(date_time_str_3)
  15. print(result) #2017-06-07 12:34:42.234000

datetime:

The following will convert the date string you give it fast and easily. This gives you back the datetime object. Notice how we need to pass the format of the datetime. If you don’t you will get an exception. This is a convenient way if you know the format before hand. But that might not always be the case.

  1. import datetime
  2.  
  3. date_str = '2017-06-06'
  4. date_time_str = '2017-06-07 12:34'
  5. date_time_str_2 = '2017-06-07 12:34:46'
  6. date_time_str_3 = '2017-06-07 12:34:42.234'
  7.  
  8. result = datetime.datetime.strptime(date_str, "%Y-%m-%d")
  9. print(result) #2017-06-06 00:00:00
  10. result = datetime.datetime.strptime(date_time_str, "%Y-%m-%d %H:%M")
  11. print(result) #2017-06-07 12:34:00
  12. result = datetime.datetime.strptime(date_time_str_2, "%Y-%m-%d %H:%M:%S")
  13. print(result) #2017-06-07 12:34:46
  14. result = datetime.datetime.strptime(date_time_str_3, "%Y-%m-%d %H:%M:%S.%f")
  15. print(result) #2017-06-07 12:34:42.234000

The above all works however the following example will not. Why do you think this is?

  1. import datetime
  2.  
  3. date_time_str = '2017-06-07 12:34:46'
  4.  
  5. try:
  6.     datetime.datetime.strptime(date_time_str, "%Y-%m-%d %H:%M:%S")
  7. except:
  8.     pass #just for this example don't do this lol

The reason is because datetime expects the correct format to be supplied. We gave it hour minute second but not milliseconds. You will get the following exception (ValueError: unconverted data remains: .234)

Timestamps:

Sometimes we want to convert the date to unix (epoch) time or vise versa.

From Date:
  1. from dateutil import parser
  2. from datetime import timezone
  3.  
  4. date_time_str = '2017-06-07 17:34:42.234'
  5. result = parser.parse(date_time_str)
  6.  
  7. timestamp = result.replace(tzinfo=timezone.utc).timestamp()
  8. print(timestamp) #1496856882.234

This gives us the timestamp as a float as 1496856882.234.

From Timestamp:
  1. from dateutil import parser
  2. import datetime
  3.  
  4. timestamp = 1496856882.234
  5.  
  6. result = datetime.datetime.fromtimestamp(timestamp)
  7. print(result) #2017-06-07 13:34:42.234000
  8.  
  9. result = datetime.datetime.utcfromtimestamp(timestamp)
  10. print(result) #2017-06-07 17:34:42.234000

Get Date Parts:

If you want to get specific date parts such as the year, month, day, hour, etc.

  1. import datetime
  2. from dateutil import parser
  3.  
  4. result = parser.parse(date_time_str_3)
  5. print(result) #2017-06-07 12:34:42.234000
  6.  
  7. year = result.year #2017
  8. month = result.month #6
  9. day = result.day #7
  10. hour = result.hour #12
  11. minute = result.minute #34
  12. second = result.second #42
  13. millisecond = result.microsecond #234000

Add To Date:

If you want to add time to a date.

  1. import datetime
  2. from dateutil import parser
  3. from datetime import timezone, timedelta
  4.  
  5. date_time_str = '2017-06-07 17:34:42.234'
  6. result = parser.parse(date_time_str)
  7. print(result) #2017-06-07 17:34:42.234000
  8.  
  9. timestamp = result.replace(tzinfo=timezone.utc).timestamp()
  10. print(timestamp) #1496856882.234
  11.  
  12. #Add 10 seconds to datetime
  13. new_time = int((datetime.datetime.fromtimestamp(timestamp) + timedelta(milliseconds=10000)).timestamp() * 1000)
  14. print(new_time) #1496856892234

As you can see you can 10 seconds has been added the datetime.

datetime strftime

  1. from datetime import datetime
  2.  
  3. now = datetime.now()
  4. datetime_str = now.strftime("%Y-%m-%d %H:%M:%S")
  5. print(datetime_str)

datetime fromisoformat

  1. from datetime import datetime
  2.  
  3. print(datetime.fromisoformat("2024-04-09 13:48:20"))