[Python-checkins] r69756 - in python/branches/release30-maint: Doc/library/functions.rst Doc/library/itertools.rst Lib/test/test_itertools.py

[raymond.hettinger]

Author: raymond.hettinger
Date: Thu Feb 19 05:49:39 2009
New Revision: 69756

Log:
Add some cross-references to the docs.  Simplify the python code equivalent for zip().  Supply an optional argument for the nth() recipe.

Modified:
   python/branches/release30-maint/Doc/library/functions.rst
   python/branches/release30-maint/Doc/library/itertools.rst
   python/branches/release30-maint/Lib/test/test_itertools.py

Modified: python/branches/release30-maint/Doc/library/functions.rst
==============================================================================
--- python/branches/release30-maint/Doc/library/functions.rst	(original)
+++ python/branches/release30-maint/Doc/library/functions.rst	Thu Feb 19 05:49:39 2009
@@ -380,6 +380,9 @@
    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])
 
@@ -595,7 +598,8 @@
    yielding the results.  If additional *iterable* arguments are passed,
    *function* must take that many arguments and is applied to the items from all
    iterables in parallel.  With multiple iterables, the iterator stops when the
-   shortest iterable is exhausted.
+   shortest iterable is exhausted.  For cases where the function inputs are
+   already arranged into argument tuples, see :func:`itertools.starmap`\.
 
 
 .. function:: max(iterable[, args...], *[, key])
@@ -948,7 +952,8 @@
    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[, key[, reverse]])
@@ -1025,7 +1030,8 @@
    Sums *start* and the items of an *iterable* from left to right and returns the
    total.  *start* defaults to ``0``. The *iterable*'s items are normally numbers,
    and are not allowed to be strings.  The fast, correct way to concatenate a
-   sequence of strings is by calling ``''.join(sequence)``.
+   sequence of strings is by calling ``''.join(sequence)``.  To add floating
+   point values with extended precision, see :func:`math.fsum`\.
 
 
 .. function:: super([type[, object-or-type]])
@@ -1137,8 +1143,7 @@
           # zip('ABCD', 'xy') --> Ax By
           iterables = map(iter, iterables)
           while iterables:
-              result = [it.next() for it in iterables]
-              yield tuple(result)
+              yield tuple(map(next, iterables))
 
    The left-to-right evaluation order of the iterables is guaranteed. This
    makes possible an idiom for clustering a data series into n-length groups

Modified: python/branches/release30-maint/Doc/library/itertools.rst
==============================================================================
--- python/branches/release30-maint/Doc/library/itertools.rst	(original)
+++ python/branches/release30-maint/Doc/library/itertools.rst	Thu Feb 19 05:49:39 2009
@@ -529,9 +529,9 @@
        "Return function(0), function(1), ..."
        return map(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"

Modified: python/branches/release30-maint/Lib/test/test_itertools.py
==============================================================================
--- python/branches/release30-maint/Lib/test/test_itertools.py	(original)
+++ python/branches/release30-maint/Lib/test/test_itertools.py	Thu Feb 19 05:49:39 2009
@@ -1219,9 +1219,9 @@
 ...     "Return function(0), function(1), ..."
 ...     return map(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"