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Commit 5bfd8ce5 authored by Raymond Hettinger's avatar Raymond Hettinger
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Add examples.

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Doc/library/itertools.rst
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......@@ -34,30 +34,30 @@ operator can be mapped across two vectors to form an efficient dot-product:
**Infinite Iterators:**
================== ================= =================================================
Iterator Arguments Results
================== ================= =================================================
:func:`count` start, [step] start, start+step, start+2*step, ...
:func:`cycle` p p0, p1, ... plast, p0, p1, ...
:func:`repeat` elem [,n] elem, elem, elem, ... endlessly or up to n times
================== ================= =================================================
================== ================= ================================================= =========================================
Iterator Arguments Results Example
================== ================= ================================================= =========================================
:func:`count` start, [step] start, start+step, start+2*step, ... ``count(10) --> 10 11 12 13 14 ...``
:func:`cycle` p p0, p1, ... plast, p0, p1, ... ``cycle('ABCD') --> A B C D A B C D ...``
:func:`repeat` elem [,n] elem, elem, elem, ... endlessly or up to n times ``repeat(10, 3) --> 10 10 10``
================== ================= ================================================= =========================================
**Iterators terminating on the shortest input sequence:**
==================== ============================ =================================================
Iterator Arguments Results
==================== ============================ =================================================
:func:`chain` p, q, ... p0, p1, ... plast, q0, q1, ...
:func:`compress` data, selectors (d[0] if s[0]), (d[1] if s[1]), ...
:func:`dropwhile` pred, seq seq[n], seq[n+1], starting when pred fails
:func:`filterfalse` pred, seq elements of seq where pred(elem) is False
:func:`groupby` iterable[, keyfunc] sub-iterators grouped by value of keyfunc(v)
:func:`islice` seq, [start,] stop [, step] elements from seq[start:stop:step]
:func:`starmap` func, seq func(\*seq[0]), func(\*seq[1]), ...
:func:`tee` it, n it1, it2 , ... itn splits one iterator into n
:func:`takewhile` pred, seq seq[0], seq[1], until pred fails
:func:`zip_longest` p, q, ... (p[0], q[0]), (p[1], q[1]), ...
==================== ============================ =================================================
==================== ============================ ================================================= =============================================================
Iterator Arguments Results Example
==================== ============================ ================================================= =============================================================
:func:`chain` p, q, ... p0, p1, ... plast, q0, q1, ... ``chain('ABC', 'DEF') --> A B C D E F``
:func:`compress` data, selectors (d[0] if s[0]), (d[1] if s[1]), ... ``compress('ABCDEF', [1,0,1,0,1,1]) --> A C E F``
:func:`dropwhile` pred, seq seq[n], seq[n+1], starting when pred fails ``dropwhile(lambda x: x<5, [1,4,6,4,1]) --> 6 4 1``
:func:`filterfalse` pred, seq elements of seq where pred(elem) is False ``ifilterfalse(lambda x: x%2, range(10)) --> 0 2 4 6 8``
:func:`groupby` iterable[, keyfunc] sub-iterators grouped by value of keyfunc(v)
:func:`islice` seq, [start,] stop [, step] elements from seq[start:stop:step] ``islice('ABCDEFG', 2, None) --> C D E F G``
:func:`starmap` func, seq func(\*seq[0]), func(\*seq[1]), ... ``starmap(pow, [(2,5), (3,2), (10,3)]) --> 32 9 1000``
:func:`takewhile` pred, seq seq[0], seq[1], until pred fails ``takewhile(lambda x: x<5, [1,4,6,4,1]) --> 1 4``
:func:`tee` it, n it1, it2 , ... itn splits one iterator into n
:func:`zip_longest` p, q, ... (p[0], q[0]), (p[1], q[1]), ... ``izip_longest('ABCD', 'xy', fillvalue='-') --> Ax By C- D-``
==================== ============================ ================================================= =============================================================
**Combinatoric generators:**
......@@ -555,43 +555,6 @@ loops that truncate the stream.
*fillvalue* defaults to ``None``.
.. _itertools-example:
Examples
--------
The following examples show common uses for each tool and demonstrate ways they
can be combined.
.. doctest::
>>> # Show a dictionary sorted and grouped by value
>>> from operator import itemgetter
>>> d = dict(a=1, b=2, c=1, d=2, e=1, f=2, g=3)
>>> di = sorted(d.items(), key=itemgetter(1))
>>> for k, g in groupby(di, key=itemgetter(1)):
... print(k, map(itemgetter(0), g))
...
1 ['a', 'c', 'e']
2 ['b', 'd', 'f']
3 ['g']
>>> # Find runs of consecutive numbers using groupby. The key to the solution
>>> # is differencing with a range so that consecutive numbers all appear in
>>> # same group.
>>> data = [ 1, 4,5,6, 10, 15,16,17,18, 22, 25,26,27,28]
>>> for k, g in groupby(enumerate(data), lambda t:t[0]-t[1]):
... print(map(operator.itemgetter(1), g))
...
[1]
[4, 5, 6]
[10]
[15, 16, 17, 18]
[22]
[25, 26, 27, 28]
.. _itertools-recipes:
Recipes
......
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