Converting date between DD MM YYYY and YYYY-MM-DD

Question

Using a Python script  I need to read a CVS file where dates are formated as DD MM YYYY  and convert them to YYYY-MM-DD before saving this into a SQLite database   This almost works  but fails because I don t provide time   from datetime import datetime  lastconnection   datetime strptime  21 12 2008     Y- m- d     ValueError  time data did not match format   data 21 12 2008  fmt  Y- m- d print lastconnection   I assume there s a method in the datetime object to perform this conversion very easily  but I can t find an example of how to do it  Thank you

User · Answer

In case you need to convert an entire column of data (from pandas DataFrame), then first convert it (pandas Series) to the datetime format using to_datetime and finally use .dt.strftime:

def conv_dates_series(df, col, old_date_format, new_date_format):

    df[col] = pd.to_datetime(df[col], format=old_date_format).dt.strftime(new_date_format)

    return(df)

Sample usage:

import pandas as pd

test_df = pd.DataFrame({"Dates": ["1900-01-01", "1999-12-31"]})

old_date_format='%d/%m/%Y'
new_date_format='%Y-%m-%d'

conv_dates_series(test_df, "Dates", old_date_format, new_date_format)

User · Answer

I am new to programming   I wanted to convert from yyyy-mm-dd to dd mm yyyy to print out a date in the format that people in my part of the world use and recognise   The accepted answer above got me on the right track   The answer I ended up with to my problem is   import datetime  today date   datetime date today   print today date   new today date   today date strftime   d  m  Y   print  new today date    The first two lines after the import statement gives today s date in the USA format  2017-01-26    The last two lines convert this to the format recognised in the UK and other countries  26 01 2017    You can shorten this code  but I left it as is because it is helpful to me as a beginner   I hope this helps other beginner programmers starting out

User · Answer

you first would need to convert string into datetime tuple  and then convert that datetime tuple to string  it would go like this   lastconnection   datetime strptime  21 12 2008     d  m  Y   strftime   Y- m- d

User · Answer

Your example code is wrong  This works   import datetime  datetime datetime strptime  21 12 2008     d  m  Y   strftime   Y- m- d     The call to strptime   parses the first argument according to the format specified in the second  so those two need to match  Then you can call strftime   to format the result into the desired final format

User · Answer

you first would need to convert string into datetime tuple  and then convert that datetime tuple to string  it would go like this   lastconnection   datetime strptime  21 12 2008     d  m  Y   strftime   Y- m- d

User · Answer

Does anyone else else think it s a waste to convert these strings to date time objects for what is  in the end  a simple text transformation  If you re certain the incoming dates will be valid  you can just use    gt  gt  gt  ddmmyyyy    21 12 2008   gt  gt  gt  yyyymmdd   ddmmyyyy 6      -    ddmmyyyy 3 5     -    ddmmyyyy  2   gt  gt  gt  yyyymmdd  2008-12-21    This will almost certainly be faster than the conversion to and from a date

User · Answer

Your example code is wrong  This works   import datetime  datetime datetime strptime  21 12 2008     d  m  Y   strftime   Y- m- d     The call to strptime   parses the first argument according to the format specified in the second  so those two need to match  Then you can call strftime   to format the result into the desired final format

User · Answer

I am new to programming   I wanted to convert from yyyy-mm-dd to dd mm yyyy to print out a date in the format that people in my part of the world use and recognise   The accepted answer above got me on the right track   The answer I ended up with to my problem is   import datetime  today date   datetime date today   print today date   new today date   today date strftime   d  m  Y   print  new today date    The first two lines after the import statement gives today s date in the USA format  2017-01-26    The last two lines convert this to the format recognised in the UK and other countries  26 01 2017    You can shorten this code  but I left it as is because it is helpful to me as a beginner   I hope this helps other beginner programmers starting out

User · Answer

Does anyone else else think it s a waste to convert these strings to date time objects for what is  in the end  a simple text transformation  If you re certain the incoming dates will be valid  you can just use    gt  gt  gt  ddmmyyyy    21 12 2008   gt  gt  gt  yyyymmdd   ddmmyyyy 6      -    ddmmyyyy 3 5     -    ddmmyyyy  2   gt  gt  gt  yyyymmdd  2008-12-21    This will almost certainly be faster than the conversion to and from a date

User · Answer

case date  03 31 2020      Above is the value stored in case date in format mm dd yyyy    demo case date split      new case date   demo 1   -  demo 0   -  demo 2   new format of date is  dd mm yyyy  test by printing it  print new case date

User · Answer

Does anyone else else think it s a waste to convert these strings to date time objects for what is  in the end  a simple text transformation  If you re certain the incoming dates will be valid  you can just use    gt  gt  gt  ddmmyyyy    21 12 2008   gt  gt  gt  yyyymmdd   ddmmyyyy 6      -    ddmmyyyy 3 5     -    ddmmyyyy  2   gt  gt  gt  yyyymmdd  2008-12-21    This will almost certainly be faster than the conversion to and from a date

User · Answer

Does anyone else else think it s a waste to convert these strings to date time objects for what is  in the end  a simple text transformation  If you re certain the incoming dates will be valid  you can just use    gt  gt  gt  ddmmyyyy    21 12 2008   gt  gt  gt  yyyymmdd   ddmmyyyy 6      -    ddmmyyyy 3 5     -    ddmmyyyy  2   gt  gt  gt  yyyymmdd  2008-12-21    This will almost certainly be faster than the conversion to and from a date

User · Answer

you first would need to convert string into datetime tuple  and then convert that datetime tuple to string  it would go like this   lastconnection   datetime strptime  21 12 2008     d  m  Y   strftime   Y- m- d

User · Answer

Your example code is wrong  This works   import datetime  datetime datetime strptime  21 12 2008     d  m  Y   strftime   Y- m- d     The call to strptime   parses the first argument according to the format specified in the second  so those two need to match  Then you can call strftime   to format the result into the desired final format

User · Answer

In case you need to convert an entire column of data (from pandas DataFrame), then first convert it (pandas Series) to the datetime format using to_datetime and finally use .dt.strftime:

def conv_dates_series(df, col, old_date_format, new_date_format):

    df[col] = pd.to_datetime(df[col], format=old_date_format).dt.strftime(new_date_format)

    return(df)

Sample usage:

import pandas as pd

test_df = pd.DataFrame({"Dates": ["1900-01-01", "1999-12-31"]})

old_date_format='%d/%m/%Y'
new_date_format='%Y-%m-%d'

conv_dates_series(test_df, "Dates", old_date_format, new_date_format)

User · Answer

you first would need to convert string into datetime tuple  and then convert that datetime tuple to string  it would go like this   lastconnection   datetime strptime  21 12 2008     d  m  Y   strftime   Y- m- d

User · Answer

case date  03 31 2020      Above is the value stored in case date in format mm dd yyyy    demo case date split      new case date   demo 1   -  demo 0   -  demo 2   new format of date is  dd mm yyyy  test by printing it  print new case date

User · Answer

Your example code is wrong  This works   import datetime  datetime datetime strptime  21 12 2008     d  m  Y   strftime   Y- m- d     The call to strptime   parses the first argument according to the format specified in the second  so those two need to match  Then you can call strftime   to format the result into the desired final format

[python] Converting date between DD/MM/YYYY and YYYY-MM-DD?

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