Re: [Zope] Weird interaction between int() and DateTime.timeTime
On Thu, 25 May 2000, Chris Withers wrote: > "Jeff K. Hoffman" wrote: > > Python 1.5.2 (#3, Mar 8 2000, 16:34:52) [C] on sunos5 > > Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam > > >>> > > >>> f = 1. > > >>> f > > 2.0 > > >>> int(f) > > 1 > > >>> > > > the int() function takes a different code path and returns 1, correctly. > > Forgive my ignorance, but in what way is 1 correct here? Surely 2 is the > what should be returned?! int() disregards everything after the decimal. >>> int(1.25) 1 >>> int(1.5) 1 >>> int(1.75) 1 >>> int(1.) 1 >>> int(2) 2 The problem comes in when you consider that the string representation functions (and thus, print) do not behave in the same way. >>> print 1.25 1.25 >>> print 1.5 1.5 >>> print 1.75 1.75 >>> print 1.9 1.9 >>> print 1.999 1.999 >>> print 1.9 1.9 >>> print 1.999 1.999 >>> print 1.9 1.9 >>> print 1.999 1.999 >>> print 1.9 2.0 > Chris --Jeff --- Jeff K. Hoffman 704.849.0731 x108 Chief Technology Officer mailto:[EMAIL PROTECTED] Going Virtual, L.L.C. http://www.goingv.com/ ___ Zope maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope-dev )
Re: [Zope] Weird interaction between int() and DateTime.timeTime
[EMAIL PROTECTED] wrote: > >From the python int doc string: > > >>> print int.__doc__ > int(x) -> integer > > Convert a string or number to an integer, if possible. > A floating point argument will be truncated towards zero. I _always_ get bitten by this :( Sorry for my igorance, Chris ___ Zope maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope-dev )
Re: [Zope] Weird interaction between int() and DateTime.timeTime
On Thu, May 25, 2000 at 07:44:44PM +0200, [EMAIL PROTECTED] wrote: > > int() works fine (truncating everything behind "."): > > >>> t.timeTime() == 953146937.0 > 0 > >>> t.timeTime() - 953146937.0 > -4.76837158203e-07 > >>> int (round (t.timeTime())) > 953146937 > Thank you, that was illuminating. Keep forgetting that floats are not always what they are printed to be. -- Andres Corrada-Emmanuel Email: [EMAIL PROTECTED] -- ___ Zope maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope-dev )
Re: [Zope] Weird interaction between int() and DateTime.timeTime
On Thu, May 25, 2000 at 06:48:51PM +0100, Chris Withers wrote: > "Jeff K. Hoffman" wrote: > > Python 1.5.2 (#3, Mar 8 2000, 16:34:52) [C] on sunos5 > > Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam > > >>> > > >>> f = 1. > > >>> f > > 2.0 > > >>> int(f) > > 1 > > >>> > > > the int() function takes a different code path and returns 1, correctly. > > Forgive my ignorance, but in what way is 1 correct here? Surely 2 is the > what should be returned?! > >From the python int doc string: >>> print int.__doc__ int(x) -> integer Convert a string or number to an integer, if possible. A floating point argument will be truncated towards zero. -- Andres Corrada-Emmanuel Email: [EMAIL PROTECTED] -- ___ Zope maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope-dev )
Re: [Zope] Weird interaction between int() and DateTime.timeTime
[EMAIL PROTECTED] writes: > >>> t.timeTime() > 953146937.0 > >>> int( t.timeTime() ) > 953146936 < This is wrong > >>> int( 953146937.0 ) > 953146937 > > Any ideas on how this can be happening. Stepping through the DateTime module > yields the sensible return value of 953146937.0 but somehow int() converts > this incorrectly. int() works fine (truncating everything behind "."): >>> t.timeTime() == 953146937.0 0 >>> t.timeTime() - 953146937.0 -4.76837158203e-07 >>> int (round (t.timeTime())) 953146937 jens -- http://www.jquade.de/ And here they are: Nitwit! Blubber! Oddment! Tweak! -- Albus Dumbledore ___ Zope maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope-dev )
Re: [Zope] Weird interaction between int() and DateTime.timeTime
"Jeff K. Hoffman" wrote: > Python 1.5.2 (#3, Mar 8 2000, 16:34:52) [C] on sunos5 > Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam > >>> > >>> f = 1. > >>> f > 2.0 > >>> int(f) > 1 > >>> > the int() function takes a different code path and returns 1, correctly. Forgive my ignorance, but in what way is 1 correct here? Surely 2 is the what should be returned?! Chris ___ Zope maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope-dev )
Re: [Zope] Weird interaction between int() and DateTime.timeTime
On Thu, 25 May 2000 [EMAIL PROTECTED] wrote: > On Thu, May 25, 2000 at 12:56:48PM -0400, Shane Hathaway wrote: > > > > Simple: DateTime has been using floating-point calculations. I believe > > all of that has been corrected, however, with the new DateTime module, > > available in the public CVS repository. > > > > Shane > > > > I don't understand how your answer explains the buggy behaviour. If > DateTime.timeTime() returns a float that's okay. Why should a call to it > wrapped with int() return the incorrect answer? > > >> t.timeTime() > 953146937.0 > >> int( t.timeTime() ) > 953146936 > >> int( 953146937.0 ) > 953146937 Check this out: Python 1.5.2 (#3, Mar 8 2000, 16:34:52) [C] on sunos5 Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam >>> >>> f = 1. >>> f 2.0 >>> int(f) 1 >>> This was on one of our Solaris boxes. Apparently, the string representation of a float having the value 1. is 2.0, while the int() function takes a different code path and returns 1, correctly. I could be wrong, but I think that's what's biting you. --Jeff --- Jeff K. Hoffman 704.849.0731 x108 Chief Technology Officer mailto:[EMAIL PROTECTED] Going Virtual, L.L.C. http://www.goingv.com/ ___ Zope maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope-dev )
Re: [Zope] Weird interaction between int() and DateTime.timeTime
Shane Hathaway wrote: > Simple: DateTime has been using floating-point calculations. I believe > all of that has been corrected, however, with the new DateTime module, > available in the public CVS repository. And will be in 2.2? Chris ___ Zope maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope-dev )
Re: [Zope] Weird interaction between int() and DateTime.timeTime
On Thu, May 25, 2000 at 12:56:48PM -0400, Shane Hathaway wrote: > > Simple: DateTime has been using floating-point calculations. I believe > all of that has been corrected, however, with the new DateTime module, > available in the public CVS repository. > > Shane > I don't understand how your answer explains the buggy behaviour. If DateTime.timeTime() returns a float that's okay. Why should a call to it wrapped with int() return the incorrect answer? >> t.timeTime() 953146937.0 >> int( t.timeTime() ) 953146936 >> int( 953146937.0 ) 953146937 -- Andres Corrada-Emmanuel Email: [EMAIL PROTECTED] -- ___ Zope maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope-dev )
Re: [Zope] Weird interaction between int() and DateTime.timeTime
[EMAIL PROTECTED] wrote: > > In a previous posting about Netscape Image problems I mentioned a weird > interaction between int() and DateTime.timeTime(). I can reproduce the error > within the python interpreter as follows- > > Python 1.5.2 (#5, Jan 6 2000, 17:10:24) [GCC egcs-2.91.66 19990314/Linux > (egcs- on linux2 > Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam > >>> from DateTime import DateTime > >>> h = 'Wed, 15 Mar 2000 19:02:17 GMT' > >>> t = DateTime( h ) > >>> print t > 2000/03/15 19:02:17 GMT > >>> t.timeTime() > 953146937.0 > >>> int( t.timeTime() ) > 953146936 < This is wrong > >>> int( 953146937.0 ) > 953146937 > > Any ideas on how this can be happening. Stepping through the DateTime module > yields the sensible return value of 953146937.0 but somehow int() converts > this incorrectly. Simple: DateTime has been using floating-point calculations. I believe all of that has been corrected, however, with the new DateTime module, available in the public CVS repository. Shane ___ Zope maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope-dev )
[Zope] Weird interaction between int() and DateTime.timeTime
In a previous posting about Netscape Image problems I mentioned a weird interaction between int() and DateTime.timeTime(). I can reproduce the error within the python interpreter as follows- Python 1.5.2 (#5, Jan 6 2000, 17:10:24) [GCC egcs-2.91.66 19990314/Linux (egcs- on linux2 Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam >>> from DateTime import DateTime >>> h = 'Wed, 15 Mar 2000 19:02:17 GMT' >>> t = DateTime( h ) >>> print t 2000/03/15 19:02:17 GMT >>> t.timeTime() 953146937.0 >>> int( t.timeTime() ) 953146936 < This is wrong >>> int( 953146937.0 ) 953146937 Any ideas on how this can be happening. Stepping through the DateTime module yields the sensible return value of 953146937.0 but somehow int() converts this incorrectly. -- Andres Corrada-Emmanuel Email: [EMAIL PROTECTED] -- ___ Zope maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope-dev )
