On Mar 12, 7:51 am, prueba...@latinmail.com wrote: > On Mar 12, 3:30 am, Raymond Hettinger <pyt...@rcn.com> wrote: > > > > > If anyone here is interested, here is a proposal I posted on the > > python-ideas list. > > > The idea is to make numbering formatting a little easier with the new > > format() builtin > > in Py2.6 and Py3.0: http://docs.python.org/library/string.html#formatspec > > > ------------------------------------------------------------- > > > Motivation: > > > Provide a simple, non-locale aware way to format a number > > with a thousands separator. > > > Adding thousands separators is one of the simplest ways to > > improve the professional appearance and readability of > > output exposed to end users. > > > In the finance world, output with commas is the norm. Finance > > users > > and non-professional programmers find the locale approach to be > > frustrating, arcane and non-obvious. > > > It is not the goal to replace locale or to accommodate every > > possible convention. The goal is to make a common task easier > > for many users. > > > Research so far: > > > Scanning the web, I've found that thousands separators are > > usually one of COMMA, PERIOD, SPACE, or UNDERSCORE. The > > COMMA is used when a PERIOD is the decimal separator. > > > James Knight observed that Indian/Pakistani numbering systems > > group by hundreds. Ben Finney noted that Chinese group by > > ten-thousands. > > > Visual Basic and its brethren (like MS Excel) use a completely > > different style and have ultra-flexible custom format specifiers > > like: "_($* #,##0_)". > > > Proposal I (from Nick Coghlan]: > > > A comma will be added to the format() specifier mini-language: > > > [[fill]align][sign][#][0][minimumwidth][,][.precision][type] > > > The ',' option indicates that commas should be included in the > > output as a > > thousands separator. As with locales which do not use a period as > > the > > decimal point, locales which use a different convention for digit > > separation will need to use the locale module to obtain > > appropriate > > formatting. > > > The proposal works well with floats, ints, and decimals. It also > > allows easy substitution for other separators. For example: > > > format(n, "6,f").replace(",", "_") > > > This technique is completely general but it is awkward in the one > > case where the commas and periods need to be swapped. > > > format(n, "6,f").replace(",", "X").replace(".", ",").replace > > ("X", ".") > > > Proposal II (to meet Antoine Pitrou's request): > > > Make both the thousands separator and decimal separator user > > specifiable > > but not locale aware. For simplicity, limit the choices to a > > comma, period, > > space, or underscore.. > > > [[fill]align][sign][#][0][minimumwidth][T[tsep]][dsep precision] > > [type] > > > Examples: > > > format(1234, "8.1f") --> ' 1234.0' > > format(1234, "8,1f") --> ' 1234,0' > > format(1234, "8T.,1f") --> ' 1.234,0' > > format(1234, "8T .f") --> ' 1 234,0' > > format(1234, "8d") --> ' 1234' > > format(1234, "8T,d") --> ' 1,234' > > > This proposal meets mosts needs (except for people wanting > > grouping > > for hundreds or ten-thousands), but it comes at the expense of > > being a little more complicated to learn and remember. Also, it > > makes it > > more challenging to write custom __format__ methods that follow > > the > > format specification mini-language. > > > For the locale module, just the "T" is necessary in a formatting > > string > > since the tool already has procedures for figuring out the actual > > separators from the local context. > > > Comments and suggestions are welcome but I draw the line at supporting > > Mayan numbering conventions ;-) > > > Raymond > > As far as I am concerned the most simple version plus a way to swap > around commas and period is all that is needed.
Thanks for the feedback. FWIW, posted a cleaned-up version of the proposal at http://www.python.org/dev/peps/pep-0378/ Raymond -- http://mail.python.org/mailman/listinfo/python-list
