CODEWITHSUNDEEP
pythonpython-3.xdatetime
Ryan Schaefer
Ryan Schaefer

Reputation: 3120

Format string for date invalid when converting to decimal day and month

Specifically I am having problems with using %-d and %-m on Windows.

The error I am getting is simple

output_dict.update({"DOB1": f"{dob.strftime('%-m/%-d/%Y') if not dob is None else 'UniqueID' + str(row)}"})
ValueError: Invalid format string

My format string looks like this:

dob.strftime('%-m/%-d/%Y')

I am fairly certain that this is because I am windows but I was wondering if there was a platform independent way of fixing this problem or if I am doing something else wrong which is causing this error.

I saw something about %e being used for the month in windows strftime but it replaces the 0 with a space instead but this is undesirable. I am trying to get these exact outputs (I use a similar format string later) 1/1/2000 and January 1 2000.

I would prefer not to use a solution like {dob.year} ect because I already have a format string that this is being placed in.

I would appreciate any ideas surrounding best practices and how I can implement a solution to this. Thank you.

Upvotes: 3

Views: 5252

Answers (1)

Jona
Jona

Reputation: 1286

A part of the answer is buried in this SA comment : Why does "%-d", or "%-e" remove the leading space or zero?

On Windows, you should use # to avoid the zero-padding (it replaces the - on Unix systems).

Here is a small example :

>>> from datetime import datetime
>>> datetime(2015, 3, 5).strftime('%d')
'05'
>>> datetime(2015, 3, 5).strftime('%-d')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: Invalid format string
>>> datetime(2015, 3, 5).strftime('%#d')
'5'

Unfortunately, I don't have a cross-platform solution.

Upvotes: 12

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