Issue8294
Created on 2010-04-02 20:42 by mark.dickinson, last changed 2022-04-11 14:56 by admin. This issue is now closed.
| Files | ||||
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| File name | Uploaded | Description | Edit | |
| fraction_from_float.patch | mark.dickinson, 2010-04-02 20:42 | |||
| fraction_from_float2.patch | mark.dickinson, 2010-04-02 21:07 | |||
| Messages (7) | |||
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| msg102198 - (view) | Author: Mark Dickinson (mark.dickinson) *  |
Date: 2010-04-02 20:42 | |
Here's a patch that allows direct construction of a Fraction instance from a float or Decimal instance, performing an exact conversion in either case.
>>> from fractions import Fraction
>>> from decimal import Decimal
>>> Fraction(1.1)
Fraction(2476979795053773, 2251799813685248)
>>> Fraction(Decimal('1.1'))
Fraction(11, 10)
>>> Fraction(Decimal(1.1))
Fraction(2476979795053773, 2251799813685248)
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| msg102199 - (view) | Author: Mark Dickinson (mark.dickinson) * |
Date: 2010-04-02 20:43 | |
(The patch is against trunk, btw.) |
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| msg102201 - (view) | Author: Raymond Hettinger (rhettinger) * |
Date: 2010-04-02 21:04 | |
The patch looks like what I expected. In the docstring, it would be nice if we kept the line with the spec for decimal strings: [-+]?[0-9]+((/|.)[0-9]+)? |
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| msg102204 - (view) | Author: Mark Dickinson (mark.dickinson) * |
Date: 2010-04-02 21:07 | |
Unfortunately, that line is wrong (or at least incomplete), since decimals in exponential form are also accepted:
>>> Fraction('2.3e4')
Fraction(23000, 1)
I could try to reinstate a fixed version.
Attaching a second version of the patch: same as the first, except for some doc tweaks. (Rewording, markup fixes.)
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| msg102205 - (view) | Author: Raymond Hettinger (rhettinger) * |
Date: 2010-04-02 21:13 | |
Being wrong is a good reason to eliminate that line from the docstring :-) So, I'm happy with the patch as-is. |
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| msg102210 - (view) | Author: Mark Dickinson (mark.dickinson) * |
Date: 2010-04-02 22:28 | |
Thanks, Raymond. Committed to trunk in r79629. Will forward port to py3k. |
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| msg102238 - (view) | Author: Mark Dickinson (mark.dickinson) * |
Date: 2010-04-03 11:40 | |
Merged to py3k in r79670. |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:56:59 | admin | set | github: 52541 |
| 2010-04-03 11:40:56 | mark.dickinson | set | status: open -> closed messages:
+ msg102238 |
| 2010-04-02 22:28:10 | mark.dickinson | set | messages:
+ msg102210 versions: - Python 2.7 |
| 2010-04-02 21:13:06 | rhettinger | set | messages: + msg102205 |
| 2010-04-02 21:07:07 | mark.dickinson | set | files:
+ fraction_from_float2.patch messages: + msg102204 |
| 2010-04-02 21:04:17 | rhettinger | set | assignee: rhettinger -> mark.dickinson resolution: accepted messages: + msg102201 |
| 2010-04-02 20:43:32 | mark.dickinson | set | messages: + msg102199 |
| 2010-04-02 20:42:41 | mark.dickinson | create | |