On Apr 25, 10:19 pm, Chris Rebert <c...@rebertia.com> wrote: > On Sun, Apr 25, 2010 at 9:42 PM, Keith <keith.braff...@gmail.com> wrote: > > On Apr 26, 12:02 am, Chris Rebert <c...@rebertia.com> wrote: > >> On Sun, Apr 25, 2010 at 8:36 PM, Keith <keith.braff...@gmail.com> wrote: > >> > I am considering writing a PEP for the inclusion of an engineering > >> > format specifier, and would appreciate input from others. > > snip > >> Relevant related information: > >> The Decimal datatype supports engineering format > >> directly:http://docs.python.org/library/decimal.html#decimal.Decimal.to_eng_st... > > > Thanks for pointing that out. Does the engineering community get by > > with the decimal module? > > > Even though this uses the to_eng_string() function, and even though I > > am using the decimal.Context class: > > >>>> c = decimal.Context(prec=5) > >>>> decimal.Decimal(1234567).to_eng_string(c) > > '1234567' > > > That is not an engineering notation string. > > Apparently either you and the General Decimal Arithmetic spec differ > on what constitutes engineering notation, there's a bug in the Python > decimal library, or you're hitting some obscure part of the spec's > definition. I don't have the expertise to know which is the case. > > The spec:http://speleotrove.com/decimal/decarith.pdf > (to-engineering-string is on page 20 if you're interested) > > Cheers, > Chris > --http://blog.rebertia.com
As has been pointed out, the Decimal implementation may not have all the features desired (i.e. forcing a particular "exponent", or a particular number of significant digits). Perhaps it could be enhanced. The other concern is computational complexity - having to perform complex engineering calculations in Decimal form is presumably more burdensome than in floats. What I've done for years is to have a function that converts an arbitrary float into a string. The function has an optional parameter that specifies the number of digits of the output. Isn't as "automatic", of course, probably showing its C origins. -f -- http://mail.python.org/mailman/listinfo/python-list
