[Python-checkins] python/dist/src/Doc/lib libitertools.tex, 1.19, 1.20

[rhettinger at users.sourceforge.net]

Update of /cvsroot/python/python/dist/src/Doc/lib
In directory sc8-pr-cvs1:/tmp/cvs-serv26769/Doc/lib

Modified Files:
	libitertools.tex 
Log Message:
Added itertools.tee()

It works like the pure python verion except:
* it stops storing data after of the iterators gets deallocated
* the data queue is implemented with two stacks instead of one dictionary.



Index: libitertools.tex
===================================================================
RCS file: /cvsroot/python/python/dist/src/Doc/lib/libitertools.tex,v
retrieving revision 1.19
retrieving revision 1.20
diff -C2 -d -r1.19 -r1.20
*** libitertools.tex	20 Oct 2003 17:01:07 -0000	1.19
--- libitertools.tex	24 Oct 2003 08:45:23 -0000	1.20
***************
*** 109,115 ****
    \end{verbatim}
  
!   Note, this is the only member of the toolkit that may require
!   significant auxiliary storage (depending on the length of the
!   iterable).
  \end{funcdesc}
  
--- 109,114 ----
    \end{verbatim}
  
!   Note, this member of the toolkit may require significant
!   auxiliary storage (depending on the length of the iterable).
  \end{funcdesc}
  
***************
*** 283,286 ****
--- 282,311 ----
  \end{funcdesc}
  
+ \begin{funcdesc}{tee}{iterable}
+   Return two independent iterators from a single iterable.
+   Equivalent to:
+ 
+   \begin{verbatim}
+      def tee(iterable):
+          def gen(next, data={}, cnt=[0]):
+              for i in count():
+                  if i == cnt[0]:
+                      item = data[i] = next()
+                      cnt[0] += 1
+                  else:
+                      item = data.pop(i)
+                  yield item
+          it = iter(iterable)
+          return (gen(it.next), gen(it.next))
+   \end{verbatim}
+ 
+   Note, this member of the toolkit may require significant auxiliary
+   storage (depending on how much temporary data needs to be stored).
+   In general, if one iterator is going use most or all of the data before
+   the other iterator, it is faster to use \function{list()} instead of
+   \function{tee()}.
+   \versionadded{2.4}
+ \end{funcdesc}
+ 
  
  \subsection{Examples \label{itertools-example}}
***************
*** 370,373 ****
--- 395,409 ----
      return sum(imap(operator.mul, vec1, vec2))
  
+ def flatten(listOfLists):
+     return list(chain(*listOfLists))
+ 
+ def repeatfunc(func, times=None, *args):
+     "Repeat calls to func with specified arguments."
+     "Example:  repeatfunc(random.random)"
+     if times is None:
+         return starmap(func, repeat(args))
+     else:
+         return starmap(func, repeat(args, times))
+ 
  def window(seq, n=2):
      "Returns a sliding window (of width n) over data from the iterable"
***************
*** 380,397 ****
          result = result[1:] + (elem,)
          yield result
- 
- def tee(iterable):
-     "Return two independent iterators from a single iterable"
-     def gen(next, data={}, cnt=[0]):
-         dpop = data.pop
-         for i in count():
-             if i == cnt[0]:
-                 item = data[i] = next()
-                 cnt[0] += 1
-             else:
-                 item = dpop(i)
-             yield item
-     next = iter(iterable).next
-     return (gen(next), gen(next))
  
  \end{verbatim}
--- 416,419 ----