Add some cross-references to the docs. Simplify the python code equivalent for izip(). Supply an optional argument for the nth() recipe.
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index fbb3f87..9de9db6 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -397,6 +397,9 @@
iterable if function(item)]`` if function is not ``None`` and ``[item for item
in iterable if item]`` if function is ``None``.
+ See :func:`itertools.filterfalse` for the complementary function that returns
+ elements of *iterable* for which *function* returns false.
+
.. function:: float([x])
@@ -1077,7 +1080,8 @@
default). They have no other explicit functionality; however they are used by
Numerical Python and other third party extensions. Slice objects are also
generated when extended indexing syntax is used. For example:
- ``a[start:stop:step]`` or ``a[start:stop, i]``.
+ ``a[start:stop:step]`` or ``a[start:stop, i]``. See :func:`itertools.islice`
+ for an alternate version that returns an iterator.
.. function:: sorted(iterable[, cmp[, key[, reverse]]])
@@ -1160,6 +1164,7 @@
and are not allowed to be strings. The fast, correct way to concatenate a
sequence of strings is by calling ``''.join(sequence)``. Note that
``sum(range(n), m)`` is equivalent to ``reduce(operator.add, range(n), m)``
+ To add floating point values with extended precision, see :func:`math.fsum`\.
.. versionadded:: 2.3
@@ -1329,7 +1334,9 @@
:func:`xrange` is intended to be simple and fast. Implementations may impose
restrictions to achieve this. The C implementation of Python restricts all
arguments to native C longs ("short" Python integers), and also requires that
- the number of elements fit in a native C long.
+ the number of elements fit in a native C long. If a larger range is needed,
+ an alternate version can be crafted using the :mod:`itertools` module:
+ ``islice(count(start, step), (stop-start+step-1)//step)``.
.. function:: zip([iterable, ...])
diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index 6fa1978..299d769 100644
--- a/Doc/library/itertools.rst
+++ b/Doc/library/itertools.rst
@@ -427,8 +427,7 @@
# izip('ABCD', 'xy') --> Ax By
iterables = map(iter, iterables)
while iterables:
- result = [it.next() for it in iterables]
- yield tuple(result)
+ yield yield tuple(map(next, iterables))
.. versionchanged:: 2.4
When no iterables are specified, returns a zero length iterator instead of
@@ -702,9 +701,9 @@
"Return function(0), function(1), ..."
return imap(function, count(start))
- def nth(iterable, n):
- "Returns the nth item or None"
- return next(islice(iterable, n, None), None)
+ def nth(iterable, n, default=None):
+ "Returns the nth item or a default value"
+ return next(islice(iterable, n, None), default)
def quantify(iterable, pred=bool):
"Count how many times the predicate is true"