[Python-checkins] r68941 - in python/trunk: Doc/library/collections.rst Doc/library/itertools.rst Lib/test/test_itertools.py Misc/NEWS Modules/itertoolsmodule.c
raymond.hettinger
python-checkins at python.org
Sun Jan 25 22:04:14 CET 2009
Author: raymond.hettinger
Date: Sun Jan 25 22:04:14 2009
New Revision: 68941
Log:
Promote combine() from a recipe to being a regular itertool.
Modified:
python/trunk/Doc/library/collections.rst
python/trunk/Doc/library/itertools.rst
python/trunk/Lib/test/test_itertools.py
python/trunk/Misc/NEWS
python/trunk/Modules/itertoolsmodule.c
Modified: python/trunk/Doc/library/collections.rst
==============================================================================
--- python/trunk/Doc/library/collections.rst (original)
+++ python/trunk/Doc/library/collections.rst Sun Jan 25 22:04:14 2009
@@ -298,7 +298,7 @@
Section 4.6.3, Exercise 19*\.
* To enumerate all distinct multisets of a given size over a given set of
- elements, see the :func:`combinations_with_replacement` function in the
+ elements, see :func:`combinations_with_replacement` in the
:ref:`itertools-recipes` for itertools::
map(Counter, combinations_with_replacement('ABC', 2)) --> AA AB AC BB BC CC
Modified: python/trunk/Doc/library/itertools.rst
==============================================================================
--- python/trunk/Doc/library/itertools.rst (original)
+++ python/trunk/Doc/library/itertools.rst Sun Jan 25 22:04:14 2009
@@ -139,6 +139,20 @@
.. 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 @@
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)!
Modified: python/trunk/Lib/test/test_itertools.py
==============================================================================
--- python/trunk/Lib/test/test_itertools.py (original)
+++ python/trunk/Lib/test/test_itertools.py Sun Jan 25 22:04:14 2009
@@ -191,6 +191,21 @@
self.assertEqual(len(set(map(id, permutations('abcde', 3)))), 1)
self.assertNotEqual(len(set(map(id, list(permutations('abcde', 3))))), 1)
+ def test_compress(self):
+ self.assertEqual(list(compress('ABCDEF', [1,0,1,0,1,1])), list('ACEF'))
+ self.assertEqual(list(compress('ABCDEF', [0,0,0,0,0,0])), list(''))
+ self.assertEqual(list(compress('ABCDEF', [1,1,1,1,1,1])), list('ABCDEF'))
+ self.assertEqual(list(compress('ABCDEF', [1,0,1])), list('AC'))
+ self.assertEqual(list(compress('ABC', [0,1,1,1,1,1])), list('BC'))
+ n = 10000
+ data = chain.from_iterable(repeat(range(6), n))
+ selectors = chain.from_iterable(repeat((0, 1)))
+ self.assertEqual(list(compress(data, selectors)), [1,3,5] * n)
+ self.assertRaises(TypeError, compress, None, range(6)) # 1st arg not iterable
+ self.assertRaises(TypeError, compress, range(6), None) # 2nd arg not iterable
+ self.assertRaises(TypeError, compress, range(6)) # too few args
+ self.assertRaises(TypeError, compress, range(6), None) # too many args
+
def test_count(self):
self.assertEqual(zip('abc',count()), [('a', 0), ('b', 1), ('c', 2)])
self.assertEqual(zip('abc',count(3)), [('a', 3), ('b', 4), ('c', 5)])
@@ -701,6 +716,9 @@
self.assertEqual(list(combinations(range(4), 3)),
[(0,1,2), (0,1,3), (0,2,3), (1,2,3)])
+ def test_compress(self):
+ self.assertEqual(list(compress('ABCDEF', [1,0,1,0,1,1])), list('ACEF'))
+
def test_count(self):
self.assertEqual(list(islice(count(10), 5)), [10, 11, 12, 13, 14])
@@ -781,6 +799,10 @@
a = []
self.makecycle(combinations([1,2,a,3], 3), a)
+ def test_compress(self):
+ a = []
+ self.makecycle(compress('ABCDEF', [1,0,1,0,1,0]), a)
+
def test_cycle(self):
a = []
self.makecycle(cycle([a]*2), a)
@@ -934,6 +956,15 @@
self.assertRaises(TypeError, list, chain(N(s)))
self.assertRaises(ZeroDivisionError, list, chain(E(s)))
+ def test_compress(self):
+ for s in ("123", "", range(1000), ('do', 1.2), xrange(2000,2200,5)):
+ n = len(s)
+ for g in (G, I, Ig, S, L, R):
+ self.assertEqual(list(compress(g(s), repeat(1))), list(g(s)))
+ self.assertRaises(TypeError, compress, X(s), repeat(1))
+ self.assertRaises(TypeError, list, compress(N(s), repeat(1)))
+ self.assertRaises(ZeroDivisionError, list, compress(E(s), repeat(1)))
+
def test_product(self):
for s in ("123", "", range(1000), ('do', 1.2), xrange(2000,2200,5)):
self.assertRaises(TypeError, product, X(s))
@@ -1125,7 +1156,7 @@
def test_keywords_in_subclass(self):
# count is not subclassable...
for cls in (repeat, izip, ifilter, ifilterfalse, chain, imap,
- starmap, islice, takewhile, dropwhile, cycle):
+ starmap, islice, takewhile, dropwhile, cycle, compress):
class Subclass(cls):
def __init__(self, newarg=None, *args):
cls.__init__(self, *args)
@@ -1262,10 +1293,6 @@
... 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', 3) --> AA AB AC BB BC CC"
... pool = tuple(iterable)
@@ -1361,9 +1388,6 @@
>>> map(sorted, powerset('ab'))
[[], ['a'], ['b'], ['a', 'b']]
->>> list(compress('abcdef', [1,0,1,0,1,1]))
-['a', 'c', 'e', 'f']
-
>>> list(combinations_with_replacement('abc', 2))
[('a', 'a'), ('a', 'b'), ('a', 'c'), ('b', 'b'), ('b', 'c'), ('c', 'c')]
Modified: python/trunk/Misc/NEWS
==============================================================================
--- python/trunk/Misc/NEWS (original)
+++ python/trunk/Misc/NEWS Sun Jan 25 22:04:14 2009
@@ -147,6 +147,8 @@
- Issue #4863: distutils.mwerkscompiler has been removed.
+- Added a new function: itertools.compress().
+
- Fix and properly document the multiprocessing module's logging
support, expose the internal levels and provide proper usage
examples.
Modified: python/trunk/Modules/itertoolsmodule.c
==============================================================================
--- python/trunk/Modules/itertoolsmodule.c (original)
+++ python/trunk/Modules/itertoolsmodule.c Sun Jan 25 22:04:14 2009
@@ -2506,6 +2506,162 @@
};
+/* compress object ************************************************************/
+
+/* 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)
+*/
+
+typedef struct {
+ PyObject_HEAD
+ PyObject *data;
+ PyObject *selectors;
+} compressobject;
+
+static PyTypeObject compress_type;
+
+static PyObject *
+compress_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+ PyObject *seq1, *seq2;
+ PyObject *data=NULL, *selectors=NULL;
+ compressobject *lz;
+
+ if (type == &compress_type && !_PyArg_NoKeywords("compress()", kwds))
+ return NULL;
+
+ if (!PyArg_UnpackTuple(args, "compress", 2, 2, &seq1, &seq2))
+ return NULL;
+
+ data = PyObject_GetIter(seq1);
+ if (data == NULL)
+ goto fail;
+ selectors = PyObject_GetIter(seq2);
+ if (selectors == NULL)
+ goto fail;
+
+ /* create compressobject structure */
+ lz = (compressobject *)type->tp_alloc(type, 0);
+ if (lz == NULL)
+ goto fail;
+ lz->data = data;
+ lz->selectors = selectors;
+ return (PyObject *)lz;
+
+fail:
+ Py_XDECREF(data);
+ Py_XDECREF(selectors);
+ return NULL;
+}
+
+static void
+compress_dealloc(compressobject *lz)
+{
+ PyObject_GC_UnTrack(lz);
+ Py_XDECREF(lz->data);
+ Py_XDECREF(lz->selectors);
+ Py_TYPE(lz)->tp_free(lz);
+}
+
+static int
+compress_traverse(compressobject *lz, visitproc visit, void *arg)
+{
+ Py_VISIT(lz->data);
+ Py_VISIT(lz->selectors);
+ return 0;
+}
+
+static PyObject *
+compress_next(compressobject *lz)
+{
+ PyObject *data = lz->data, *selectors = lz->selectors;
+ PyObject *datum, *selector;
+ PyObject *(*datanext)(PyObject *) = *Py_TYPE(data)->tp_iternext;
+ PyObject *(*selectornext)(PyObject *) = *Py_TYPE(selectors)->tp_iternext;
+ int ok;
+
+ while (1) {
+ /* Steps: get datum, get selector, evaluate selector.
+ Order is important (to match the pure python version
+ in terms of which input gets a chance to raise an
+ exception first).
+ */
+
+ datum = datanext(data);
+ if (datum == NULL)
+ return NULL;
+
+ selector = selectornext(selectors);
+ if (selector == NULL) {
+ Py_DECREF(datum);
+ return NULL;
+ }
+
+ ok = PyObject_IsTrue(selector);
+ Py_DECREF(selector);
+ if (ok == 1)
+ return datum;
+ Py_DECREF(datum);
+ if (ok == -1)
+ return NULL;
+ }
+}
+
+PyDoc_STRVAR(compress_doc,
+"compress(data sequence, selector sequence) --> iterator over selected data\n\
+\n\
+Return data elements corresponding to true selector elements.\n\
+Forms a shorter iterator from selected data elements using the\n\
+selectors to choose the data elements.");
+
+static PyTypeObject compress_type = {
+ PyVarObject_HEAD_INIT(NULL, 0)
+ "itertools.compress", /* tp_name */
+ sizeof(compressobject), /* tp_basicsize */
+ 0, /* tp_itemsize */
+ /* methods */
+ (destructor)compress_dealloc, /* tp_dealloc */
+ 0, /* tp_print */
+ 0, /* tp_getattr */
+ 0, /* tp_setattr */
+ 0, /* tp_compare */
+ 0, /* tp_repr */
+ 0, /* tp_as_number */
+ 0, /* tp_as_sequence */
+ 0, /* tp_as_mapping */
+ 0, /* tp_hash */
+ 0, /* tp_call */
+ 0, /* tp_str */
+ PyObject_GenericGetAttr, /* tp_getattro */
+ 0, /* tp_setattro */
+ 0, /* tp_as_buffer */
+ Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+ Py_TPFLAGS_BASETYPE, /* tp_flags */
+ compress_doc, /* tp_doc */
+ (traverseproc)compress_traverse, /* tp_traverse */
+ 0, /* tp_clear */
+ 0, /* tp_richcompare */
+ 0, /* tp_weaklistoffset */
+ PyObject_SelfIter, /* tp_iter */
+ (iternextfunc)compress_next, /* tp_iternext */
+ 0, /* tp_methods */
+ 0, /* tp_members */
+ 0, /* tp_getset */
+ 0, /* tp_base */
+ 0, /* tp_dict */
+ 0, /* tp_descr_get */
+ 0, /* tp_descr_set */
+ 0, /* tp_dictoffset */
+ 0, /* tp_init */
+ 0, /* tp_alloc */
+ compress_new, /* tp_new */
+ PyObject_GC_Del, /* tp_free */
+};
+
+
/* ifilter object ************************************************************/
typedef struct {
@@ -3552,6 +3708,7 @@
&starmap_type,
&imap_type,
&chain_type,
+ &compress_type,
&ifilter_type,
&ifilterfalse_type,
&count_type,
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