Minor updates:

* Updated comment on design of imap()
* Added untraversed object in izip() structure
* Replaced the pairwise() example with a more general window() example

Doc/lib/libitertools.tex

@@ -358,10 +358,6 @@ from building blocks.
 ...     "Returns True if pred(x) is False for every element in the iterable"
 ...     return not nth(ifilter(pred, seq), 0)
 
->>> def pairwise(seq):
-...     "s -> (s0,s1), (s1,s2), (s2, s3), ..."
-...     return izip(seq, islice(seq,1,None))
-
 >>> def padnone(seq):
 ...     "Returns the sequence elements and then returns None indefinitely"
 ...     return chain(seq, repeat(None))
@@ -373,4 +369,15 @@ from building blocks.
 >>> def dotproduct(vec1, vec2):
 ...     return sum(imap(operator.mul, vec1, vec2))
 
+>>> def window(seq, n=2):
+...     "Returns a sliding window (of width n) over data from the iterable"
+...     "   s -> (s0,s1,...s[n-1]), (s1,s2,...,sn), ...                   "
+...     it = iter(seq)
+...     result = tuple(islice(it, n))
+...     if len(result) == n:
+...         yield result    
+...     for elem in it:
+...         result = result[1:] + (elem,)
+...         yield result
+
 \end{verbatim}