Promote compress() from a recipe to being a regular itertool.

1 files changed, 14 insertions, 4 deletions

diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index aef3f6a..903284e 100644
--- a/Doc/library/itertools.rst
+++ b/Doc/library/itertools.rst
@@ -139,6 +139,20 @@ loops that truncate the stream.
 
    .. versionadded:: 2.6
 
+.. function:: compress(data, selectors)
+
+   Make an iterator that filters elements from *data* returning only those that
+   have a corresponding element in *selectors* that evaluates to ``True``.
+   Stops when either the *data* or *selectors* iterables have been exhausted.
+   Equivalent to::
+
+       def compress(data, selectors):
+           # compress('ABCDEF', [1,0,1,0,1,1]) --> A C E F
+           return (d for d, s in izip(data, selectors) if s)
+
+   .. versionadded:: 2.7
+
+
 .. function:: count([n])
 
    Make an iterator that returns consecutive integers starting with *n*. If not
@@ -679,10 +693,6 @@ which incur interpreter overhead.
        for n in xrange(2**len(pairs)):
            yield set(x for m, x in pairs if m&n)
 
-   def compress(data, selectors):
-       "compress('ABCDEF', [1,0,1,0,1,1]) --> A C E F"
-       return (d for d, s in izip(data, selectors) if s)
-
    def combinations_with_replacement(iterable, r):
        "combinations_with_replacement('ABC', 2) --> AA AB AC BB BC CC"
        # number items returned:  (n+r-1)! / r! / (n-1)!