diff options
| -rw-r--r-- | Doc/library/functions.rst | 15 | ||||
| -rw-r--r-- | Doc/library/itertools.rst | 6 | ||||
| -rw-r--r-- | Lib/test/test_itertools.py | 6 |
3 files changed, 16 insertions, 11 deletions
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst index f9205b6..39aab16 100644 --- a/Doc/library/functions.rst +++ b/Doc/library/functions.rst @@ -380,6 +380,9 @@ are always available. They are listed here in alphabetical order. 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 @@ are always available. They are listed here in alphabetical order. 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]) @@ -953,7 +957,8 @@ are always available. They are listed here in alphabetical order. 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]]) @@ -1030,7 +1035,8 @@ are always available. They are listed here in alphabetical order. 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]]) @@ -1145,8 +1151,7 @@ are always available. They are listed here in alphabetical order. # 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 diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst index 491cb18..32ad792 100644 --- a/Doc/library/itertools.rst +++ b/Doc/library/itertools.rst @@ -615,9 +615,9 @@ which incur interpreter overhead. "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" diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py index 8492484..cf0ca24 100644 --- a/Lib/test/test_itertools.py +++ b/Lib/test/test_itertools.py @@ -1419,9 +1419,9 @@ Samuele ... "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" |