Datetime Object without leading zero

Question

I've come across several answers (1, 2, 3) regarding the removal of leading zeros on python3 datetime objects.

One of the most voted answers states:

On Windows, you would use #, e.g. %Y/%#m/%#d

The code above doesn't work for me. I've also tried the Linux solution, which uses - instead of #, without success.

Code:

loop_date = "1950-1-1"
date_obj = datetime.strptime(loop_date, '%Y-%m-%d') # or '%Y-%#m-%#d' which produces the errors below
date_obj += timedelta(days=1)
print(date_obj)
# This the prints `1954-01-02` but I need `1954-1-2`

Traceback:

Traceback (most recent call last):
  File "C:/collect_games.py", line 84, in <module>
    date_obj = datetime.strptime(loop_date, '%Y-%-m-%d')
  File "E:\Anaconda3\lib\_strptime.py", line 565, in _strptime_datetime
    tt, fraction = _strptime(data_string, format)
  File "E:\Anaconda3\lib\_strptime.py", line 354, in _strptime
    (bad_directive, format)) from None
ValueError: '#' is a bad directive in format '%Y-%#m#%d'

What's most pythonic approach to this problem?

you are parsing a time datetime here ... the `-` is applied when formatting an datetime into a string .... python does not need `02` inside a string to understands its the month or whatever ... to parse the month from a string into a datetime object ? — Patrick Artner, Apr 05 '18 at 14:32
I need the output to be formatted without the leading zero, which doesn't happen with my current code.. — Pedro Lobito, Apr 05 '18 at 14:33
@Kasramvd in php you can use `j` for Day of the month without leading zeros or `d` for Day of the month with leading zeros — Pedro Lobito, Apr 05 '18 at 14:34
You're creating a `datetime` object with a standard representation. Removing those zeros is another problem and related to the string representation of the object. — Mazdak, Apr 05 '18 at 14:35
If you want to create a string representation from a datetime object without padding zeros you might want to use `strftime` method as is mentioned in @Patrick's answer. — Mazdak, Apr 05 '18 at 14:41
The code on Patrick's answer, and the one on my question, runs fine on online compilers, but not on my windows python3.6 installation. I don't have a solution yet, but now I'm this is an installation problem rather than a syntax one. — Pedro Lobito, Apr 05 '18 at 14:48

Patrick Artner · Accepted Answer · 2018-04-05T14:52:56.367

7

You are confusing the formats of parsing (a string into a dt) and formatting (a dt into a string):

This works on linux (or online via http://pyfiddle.io):

import datetime 

dt = datetime.datetime.now()

# format datetime as string
print(datetime.datetime.strftime(dt, '%Y-%-m-%-d'))  # - acts to remove 0 AND as delimiter

# parse a string into a datetime object
dt2 = datetime.datetime.strptime("1022-4-09", '%Y-%m-%d')

print(dt2)

Output:

2018-4-5
1022-04-09 00:00:00

The - when formatting a string acts to remove the leading 0 AND as delimiter - for parsing it only needs to be placed as delimiter - parsing works on on either 02 or 2 for %m

This works on Windows (VS2017):

from datetime import datetime, timedelta

loop_date = "1950-1-1"
date_obj = datetime.strptime(loop_date, '%Y-%m-%d')
date_obj += timedelta(days=1)
print(date_obj)   # output the datetime-object

print(datetime.strftime(date_obj,'%Y-%#m-%#d'))  # output it formatted

Output:

1950-01-02 00:00:00
1950-1-2

edited Apr 05 '18 at 14:52

answered Apr 05 '18 at 14:37

Patrick Artner

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Your code produces : `Traceback (most recent call last): File "C:/collect_games.py", line 7, in print(datetime.datetime.strftime(dt, '%Y-%-m-%d')) ValueError: Invalid format string ` on `python 3.6` and there's nothing different from the question's code, which yields the same error. – Pedro Lobito Apr 05 '18 at 14:39
@PedroLobito copy my code into http://www.pyfiddle.io - it works as 2.7 and 3.6 ? – Patrick Artner Apr 05 '18 at 14:41
Your code runs fine but not on my windows python3.6 . I'm almost sure this is an installation problem rather than a syntax one. – Pedro Lobito Apr 05 '18 at 14:45
@PedroLobito See edit. pyfiddle.io is a linux server – Patrick Artner Apr 05 '18 at 14:47
***This works on Windows (VS2017)*** it does. Strange, because I've tried that...I guess I've to apply the "removal filter" (`-`) only at `print` time. I'll mark your answer as correct. Thank you. – Pedro Lobito Apr 05 '18 at 14:52
@PedroLobito RemoveAll - Filter would be `#` ;) for windows. Sorry for the confusion with linus syntax. – Patrick Artner Apr 05 '18 at 14:54
NP, all set, appreciated! – Pedro Lobito Apr 05 '18 at 18:53

Datetime Object without leading zero

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