Python datetime formatting without zero-padding

The other alternate to avoid the "all or none" leading zero aspect above is to place a minus in front of the field type:

mydatetime.strftime('%-m/%d/%Y %-I:%M%p')

Then this: '4/10/2015 03:00AM'

Becomes: '4/10/2015 3:00AM'

You can optionally place a minus in front of the day if desired.

Edit: The minus feature derives from the GNU C library (“glibc”) as mentioned in the Linux strftime manpage under “Glibc notes”

The new string formatting system provides an alternative to strftime. It's quite readable -- indeed, it might be preferable to strftime on that account. Not to mention the fact that it doesn't zero-pad:

>>> '{d.month}/{d.day}/{d.year}'.format(d=datetime.datetime.now())
'3/1/2012'

Since you probably want zero padding in the minute field, you could do this:

>>> '{d.month}/{d.day}/{d.year} {d.hour}:{d.minute:02}'.format(d=now)
'3/1/2012 20:00'

If you want "regular" time instead of "military" time, you can still use the standard strftime specifiers as well. Conveniently, for our purposes, strftime does provide a code for the 12-hour time padded with a blank instead of a leading zero:

'{d.month}/{d.day}/{d.year} {d:%l}:{d.minute:02}{d:%p}'.format(d=now)
'4/4/2014  6:00PM'

This becomes somewhat less readable, alas. And as @mlissner points out, strftime will fail on some (all?) platforms for dates before 1900.

The formatting options available with datetime.strftime() will all zero-pad. You could of course roll you own formatting function, but the easiest solution in this case might be to post-process the result of datetime.strftime():

s = mydatetime.strftime('%m/%d/%Y %I:%M%p').lstrip("0").replace(" 0", " ")

Accepted answer not a proper solution (IMHO) The proper documented methods:

In Linux "#" is replaced by "-":

%-d, %-H, %-I, %-j, %-m, %-M, %-S, %-U, %-w, %-W, %-y, %-Y

In Windows "-" is replaced by "#":

%#d, %#H, %#I, %#j, %#m, %#M, %#S, %#U, %#w, %#W, %#y, %#Y

#Linux
mydatetime.strftime('%-m/%d/%Y %-I:%M%p')

# Windows
mydatetime.strftime('%#m/%d/%Y %#I:%M%p')

Source: https://msdn.microsoft.com/en-us/library/fe06s4ak.aspx

As stated by Sagneta: The # hash trick on Windows is only available to native python executable. this will not work for cygwin-based python implementations.