Author mark.dickinson
Recipients eric.smith, mark.dickinson, sk1d
Date 2018-02-08.08:14:26
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Message-id <1518077667.03.0.467229070634.issue32790@psf.upfronthosting.co.za>
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The behaviour here is intentional, though the reasons for doing it this way are at least partly historical: it's the way that %g formatting works in C's *printf functions (see C99 7.19.6.1p8 for details), and as a direct result of that it's also the way that old-style %-based formatting works in Python. That behaviour then got transferred to the new-style .format-based formatting for consistency.

I don't think we can or should change the current behaviour here: there's a significant risk of breaking existing code.

However, note that C does offer an *alternate* mode for .g-style formatting, using the '#' character, and this is also available in Python's formatting, both %-based and format-based:

>>> "%.2g" % 0.1950
'0.2'
>>> "%#.2g" % 0.1950
'0.20'

and

>>> format(0.1950, '.2g')
'0.2'
>>> format(0.1950, '#.2g')
'0.20'

Does this meet your needs?
History
Date User Action Args
2018-02-08 08:14:27mark.dickinsonsetrecipients: + mark.dickinson, eric.smith, sk1d
2018-02-08 08:14:27mark.dickinsonsetmessageid: <1518077667.03.0.467229070634.issue32790@psf.upfronthosting.co.za>
2018-02-08 08:14:27mark.dickinsonlinkissue32790 messages
2018-02-08 08:14:26mark.dickinsoncreate