Manually merge r68095,68186,68187,68188,68190 from 2.6 branch.

This commit is contained in:
Georg Brandl 2009-01-03 22:03:11 +00:00
parent c63785db86
commit fe427895b5
5 changed files with 25 additions and 8 deletions

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@ -1923,13 +1923,14 @@ suggest, so we trap :const:`Inexact` to signal a need for more precision:
def float_to_decimal(f): def float_to_decimal(f):
"Convert a floating point number to a Decimal with no loss of information" "Convert a floating point number to a Decimal with no loss of information"
n, d = f.as_integer_ratio() n, d = f.as_integer_ratio()
with localcontext() as ctx: numerator, denominator = Decimal(n), Decimal(d)
ctx.traps[Inexact] = True ctx = Context(prec=60)
while True: result = ctx.divide(numerator, denominator)
try: while ctx.flags[Inexact]:
return Decimal(n) / Decimal(d) ctx.flags[Inexact] = False
except Inexact: ctx.prec *= 2
ctx.prec += 1 result = ctx.divide(numerator, denominator)
return result
.. doctest:: .. doctest::

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@ -111,7 +111,7 @@ class Fraction(Rational):
""" """
if isinstance(f, numbers.Integral): if isinstance(f, numbers.Integral):
f = float(f) return cls(f)
elif not isinstance(f, float): elif not isinstance(f, float):
raise TypeError("%s.from_float() only takes floats, not %r (%s)" % raise TypeError("%s.from_float() only takes floats, not %r (%s)" %
(cls.__name__, f, type(f).__name__)) (cls.__name__, f, type(f).__name__))

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@ -354,6 +354,10 @@ def nsmallest(n, iterable, key=None):
Equivalent to: sorted(iterable, key=key)[:n] Equivalent to: sorted(iterable, key=key)[:n]
""" """
if key is None:
it = izip(iterable, count()) # decorate
result = _nsmallest(n, it)
return map(itemgetter(0), result) # undecorate
in1, in2 = tee(iterable) in1, in2 = tee(iterable)
it = izip(imap(key, in1), count(), in2) # decorate it = izip(imap(key, in1), count(), in2) # decorate
result = _nsmallest(n, it) result = _nsmallest(n, it)
@ -365,6 +369,10 @@ def nlargest(n, iterable, key=None):
Equivalent to: sorted(iterable, key=key, reverse=True)[:n] Equivalent to: sorted(iterable, key=key, reverse=True)[:n]
""" """
if key is None:
it = izip(iterable, imap(neg, count())) # decorate
result = _nlargest(n, it)
return map(itemgetter(0), result) # undecorate
in1, in2 = tee(iterable) in1, in2 = tee(iterable)
it = izip(imap(key, in1), imap(neg, count()), in2) # decorate it = izip(imap(key, in1), imap(neg, count()), in2) # decorate
result = _nlargest(n, it) result = _nlargest(n, it)

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@ -139,6 +139,8 @@ class FractionTest(unittest.TestCase):
def testFromFloat(self): def testFromFloat(self):
self.assertRaises(TypeError, F.from_float, 3+4j) self.assertRaises(TypeError, F.from_float, 3+4j)
self.assertEquals((10, 1), _components(F.from_float(10))) self.assertEquals((10, 1), _components(F.from_float(10)))
bigint = 1234567890123456789
self.assertEquals((bigint, 1), _components(F.from_float(bigint)))
self.assertEquals((0, 1), _components(F.from_float(-0.0))) self.assertEquals((0, 1), _components(F.from_float(-0.0)))
self.assertEquals((10, 1), _components(F.from_float(10.0))) self.assertEquals((10, 1), _components(F.from_float(10.0)))
self.assertEquals((-5, 2), _components(F.from_float(-2.5))) self.assertEquals((-5, 2), _components(F.from_float(-2.5)))

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@ -127,6 +127,12 @@ Library
- Issue #4646: distutils was choking on empty options arg in the setup - Issue #4646: distutils was choking on empty options arg in the setup
function. Original patch by Thomas Heller. function. Original patch by Thomas Heller.
- Fractions.from_float() no longer loses precision for integers too big to
cast as floats.
- Issue 4790: The nsmallest() and nlargest() functions in the heapq module
did unnecessary work in the common case where no key function was specified.
- Issue #3767: Convert Tk object to string in tkColorChooser. - Issue #3767: Convert Tk object to string in tkColorChooser.
- Issue #3248: Allow placing ScrolledText in a PanedWindow. - Issue #3248: Allow placing ScrolledText in a PanedWindow.