mirror of https://github.com/python/cpython
Add some cross-references to the docs. Simplify the python code equivalent for izip(). Supply an optional argument for the nth() recipe.
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@ -397,6 +397,9 @@ available. They are listed here in alphabetical order.
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iterable if function(item)]`` if function is not ``None`` and ``[item for item
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in iterable if item]`` if function is ``None``.
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See :func:`itertools.filterfalse` for the complementary function that returns
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elements of *iterable* for which *function* returns false.
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.. function:: float([x])
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@ -1077,7 +1080,8 @@ available. They are listed here in alphabetical order.
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default). They have no other explicit functionality; however they are used by
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Numerical Python and other third party extensions. Slice objects are also
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generated when extended indexing syntax is used. For example:
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``a[start:stop:step]`` or ``a[start:stop, i]``.
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``a[start:stop:step]`` or ``a[start:stop, i]``. See :func:`itertools.islice`
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for an alternate version that returns an iterator.
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.. function:: sorted(iterable[, cmp[, key[, reverse]]])
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@ -1160,6 +1164,7 @@ available. They are listed here in alphabetical order.
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and are not allowed to be strings. The fast, correct way to concatenate a
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sequence of strings is by calling ``''.join(sequence)``. Note that
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``sum(range(n), m)`` is equivalent to ``reduce(operator.add, range(n), m)``
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To add floating point values with extended precision, see :func:`math.fsum`\.
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.. versionadded:: 2.3
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@ -1323,7 +1328,9 @@ available. They are listed here in alphabetical order.
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:func:`xrange` is intended to be simple and fast. Implementations may impose
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restrictions to achieve this. The C implementation of Python restricts all
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arguments to native C longs ("short" Python integers), and also requires that
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the number of elements fit in a native C long.
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the number of elements fit in a native C long. If a larger range is needed,
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an alternate version can be crafted using the :mod:`itertools` module:
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``islice(count(start, step), (stop-start+step-1)//step)``.
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.. function:: zip([iterable, ...])
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@ -338,8 +338,7 @@ loops that truncate the stream.
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# izip('ABCD', 'xy') --> Ax By
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iterables = map(iter, iterables)
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while iterables:
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result = [it.next() for it in iterables]
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yield tuple(result)
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yield yield tuple(map(next, iterables))
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.. versionchanged:: 2.4
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When no iterables are specified, returns a zero length iterator instead of
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@ -613,9 +612,9 @@ which incur interpreter overhead.
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"Return function(0), function(1), ..."
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return imap(function, count(start))
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def nth(iterable, n):
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"Returns the nth item or None"
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return next(islice(iterable, n, None), None)
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def nth(iterable, n, default=None):
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"Returns the nth item or a default value"
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return next(islice(iterable, n, None), default)
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def quantify(iterable, pred=bool):
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"Count how many times the predicate is true"
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@ -1200,9 +1200,9 @@ Samuele
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... "Return function(0), function(1), ..."
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... return imap(function, count(start))
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>>> def nth(iterable, n):
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... "Returns the nth item or None"
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... return next(islice(iterable, n, None), None)
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>>> def nth(iterable, n, default=None):
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... "Returns the nth item or a default value"
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... return next(islice(iterable, n, None), default)
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>>> def quantify(iterable, pred=bool):
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... "Count how many times the predicate is true"
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