Replace the window() example with pairwise() which demonstrates tee().

Author: rhettinger

Doc/lib/libitertools.tex

@@ -405,15 +405,9 @@ \subsection{Examples \label{itertools-example}}
  else:
  return starmap(func, repeat(args, times))
 
-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
+def pairwise(iterable):
+ "s -> (s0,s1), (s1,s2), (s2, s3), ..."
+ a, b = tee(iterable)
+ return izip(a, islice(b, 1, None))
 
 \end{verbatim}

Lib/test/test_itertools.py

@@ -623,16 +623,10 @@ def f(t):
 ... else:
 ... return starmap(func, repeat(args, times))
 
->>> 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
+>>> def pairwise(iterable):
+... "s -> (s0,s1), (s1,s2), (s2, s3), ..."
+... a, b = tee(iterable)
+... return izip(a, islice(b, 1, None))
 
 This is not part of the examples but it tests to make sure the definitions
 perform as purported.
@@ -681,10 +675,13 @@ def f(t):
 >>> take(5, imap(int, repeatfunc(random.random)))
 [0, 0, 0, 0, 0]
 
->>> list(window('abc'))
-[('a', 'b'), ('b', 'c')]
+>>> list(pairwise('abcd'))
+[('a', 'b'), ('b', 'c'), ('c', 'd')]
 
->>> list(window('abc',5))
+>>> list(pairwise([]))
+[]
+
+>>> list(pairwise('a'))
 []
 
 >>> list(islice(padnone('abc'), 0, 6))