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Make built-in zip() equal to itertools.izip().

Browse source 
I mea, *really* equal -- for now, the implementation just imports
itertools. :-)
The only other changes necessary were various unit tests that were
assuming zip() returns a real list.  No "real" code made this assumption.
This commit is contained in:
Guido van Rossum 2006-08-24 19:48:10 +00:00
parent d38abe9484
commit 801f0d78b5
6 changed files with 62 additions and 139 deletions
Download patch file Download diff file Expand all files Collapse all files

16
Lib/test/test_builtin.py
View file

@ -1554,18 +1554,18 @@ class BuiltinTest(unittest.TestCase):
a = (1, 2, 3)
b = (4, 5, 6)
t = [(1, 4), (2, 5), (3, 6)]
self.assertEqual(zip(a, b), t)
self.assertEqual(list(zip(a, b)), t)
b = [4, 5, 6]
self.assertEqual(zip(a, b), t)
self.assertEqual(list(zip(a, b)), t)
b = (4, 5, 6, 7)
self.assertEqual(zip(a, b), t)
self.assertEqual(list(zip(a, b)), t)
class I:
def __getitem__(self, i):
if i < 0 or i > 2: raise IndexError
return i + 4
self.assertEqual(zip(a, I()), t)
self.assertEqual(zip(), [])
self.assertEqual(zip(*[]), [])
self.assertEqual(list(zip(a, I())), t)
self.assertEqual(list(zip()), [])
self.assertEqual(list(zip(*[])), [])
self.assertRaises(TypeError, zip, None)
class G:
pass
@ -1581,7 +1581,7 @@ class BuiltinTest(unittest.TestCase):
else:
return i
self.assertEqual(
zip(SequenceWithoutALength(), xrange(2**30)),
list(zip(SequenceWithoutALength(), xrange(2**30))),
list(enumerate(range(5)))
)
@ -1591,7 +1591,7 @@ class BuiltinTest(unittest.TestCase):
raise ValueError
else:
return i
self.assertRaises(ValueError, zip, BadSeq(), BadSeq())
self.assertRaises(ValueError, list, zip(BadSeq(), BadSeq()))
class TestSorted(unittest.TestCase):

2
Lib/test/test_enumerate.py
View file

@ -122,7 +122,7 @@ class TestEmpty(EnumerateTestCase):
class TestBig(EnumerateTestCase):
seq = range(10,20000,2)
res = zip(range(20000), seq)
res = list(zip(range(20000), seq))
class TestReversed(unittest.TestCase):

29
Lib/test/test_iter.py
View file

@ -423,21 +423,21 @@ class TestCase(unittest.TestCase):
# Test zip()'s use of iterators.
def test_builtin_zip(self):
self.assertEqual(zip(), [])
self.assertEqual(zip(*[]), [])
self.assertEqual(zip(*[(1, 2), 'ab']), [(1, 'a'), (2, 'b')])
self.assertEqual(list(zip()), [])
self.assertEqual(list(zip(*[])), [])
self.assertEqual(list(zip(*[(1, 2), 'ab'])), [(1, 'a'), (2, 'b')])
self.assertRaises(TypeError, zip, None)
self.assertRaises(TypeError, zip, range(10), 42)
self.assertRaises(TypeError, zip, range(10), zip)
self.assertEqual(zip(IteratingSequenceClass(3)),
self.assertEqual(list(zip(IteratingSequenceClass(3))),
[(0,), (1,), (2,)])
self.assertEqual(zip(SequenceClass(3)),
self.assertEqual(list(zip(SequenceClass(3))),
[(0,), (1,), (2,)])
d = {"one": 1, "two": 2, "three": 3}
self.assertEqual(d.items(), zip(d, d.itervalues()))
self.assertEqual(d.items(), list(zip(d, d.itervalues())))
# Generate all ints starting at constructor arg.
class IntsFrom:
@ -459,7 +459,7 @@ class TestCase(unittest.TestCase):
f.close()
f = open(TESTFN, "r")
try:
self.assertEqual(zip(IntsFrom(0), f, IntsFrom(-100)),
self.assertEqual(list(zip(IntsFrom(0), f, IntsFrom(-100))),
[(0, "a\n", -100),
(1, "bbb\n", -99),
(2, "cc\n", -98)])
@ -470,7 +470,7 @@ class TestCase(unittest.TestCase):
except OSError:
pass
self.assertEqual(zip(xrange(5)), [(i,) for i in range(5)])
self.assertEqual(list(zip(xrange(5))), [(i,) for i in range(5)])
# Classes that lie about their lengths.
class NoGuessLen5:
@ -487,16 +487,19 @@ class TestCase(unittest.TestCase):
def __len__(self):
return 30
def lzip(*args):
return list(zip(*args))
self.assertEqual(len(Guess3Len5()), 3)
self.assertEqual(len(Guess30Len5()), 30)
self.assertEqual(zip(NoGuessLen5()), zip(range(5)))
self.assertEqual(zip(Guess3Len5()), zip(range(5)))
self.assertEqual(zip(Guess30Len5()), zip(range(5)))
self.assertEqual(lzip(NoGuessLen5()), lzip(range(5)))
self.assertEqual(lzip(Guess3Len5()), lzip(range(5)))
self.assertEqual(lzip(Guess30Len5()), lzip(range(5)))
expected = [(i, i) for i in range(5)]
for x in NoGuessLen5(), Guess3Len5(), Guess30Len5():
for y in NoGuessLen5(), Guess3Len5(), Guess30Len5():
self.assertEqual(zip(x, y), expected)
self.assertEqual(lzip(x, y), expected)
# This test case will be removed if we don't have Unicode
def test_unicode_join_endcase(self):
@ -861,7 +864,7 @@ class TestCase(unittest.TestCase):
a = range(5)
e = enumerate(a)
b = iter(e)
self.assertEqual(list(b), zip(range(5), range(5)))
self.assertEqual(list(b), list(zip(range(5), range(5))))
self.assertEqual(list(b), [])

34
Lib/test/test_itertools.py
View file

@ -6,6 +6,9 @@ import sys
import operator
import random
def lzip(*args):
return list(zip(*args))
def onearg(x):
'Test function of one argument'
return 2*x
@ -47,9 +50,9 @@ class TestBasicOps(unittest.TestCase):
self.assertRaises(TypeError, chain, 2, 3)
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)])
self.assertEqual(take(2, zip('abc',count(3))), [('a', 3), ('b', 4)])
self.assertEqual(lzip('abc',count()), [('a', 0), ('b', 1), ('c', 2)])
self.assertEqual(lzip('abc',count(3)), [('a', 3), ('b', 4), ('c', 5)])
self.assertEqual(take(2, lzip('abc',count(3))), [('a', 3), ('b', 4)])
self.assertRaises(TypeError, count, 2, 3)
self.assertRaises(TypeError, count, 'a')
c = count(sys.maxint-2) # verify that rollover doesn't crash
@ -176,27 +179,28 @@ class TestBasicOps(unittest.TestCase):
self.assertRaises(TypeError, ifilterfalse(range(6), range(6)).next)
def test_izip(self):
# XXX This is rather silly now that builtin zip() calls izip()...
ans = [(x,y) for x, y in izip('abc',count())]
self.assertEqual(ans, [('a', 0), ('b', 1), ('c', 2)])
self.assertEqual(list(izip('abc', range(6))), zip('abc', range(6)))
self.assertEqual(list(izip('abcdef', range(3))), zip('abcdef', range(3)))
self.assertEqual(take(3,izip('abcdef', count())), zip('abcdef', range(3)))
self.assertEqual(list(izip('abcdef')), zip('abcdef'))
self.assertEqual(list(izip()), zip())
self.assertEqual(list(izip('abc', range(6))), lzip('abc', range(6)))
self.assertEqual(list(izip('abcdef', range(3))), lzip('abcdef', range(3)))
self.assertEqual(take(3,izip('abcdef', count())), lzip('abcdef', range(3)))
self.assertEqual(list(izip('abcdef')), lzip('abcdef'))
self.assertEqual(list(izip()), lzip())
self.assertRaises(TypeError, izip, 3)
self.assertRaises(TypeError, izip, range(3), 3)
# Check tuple re-use (implementation detail)
self.assertEqual([tuple(list(pair)) for pair in izip('abc', 'def')],
zip('abc', 'def'))
lzip('abc', 'def'))
self.assertEqual([pair for pair in izip('abc', 'def')],
zip('abc', 'def'))
lzip('abc', 'def'))
ids = map(id, izip('abc', 'def'))
self.assertEqual(min(ids), max(ids))
ids = map(id, list(izip('abc', 'def')))
self.assertEqual(len(dict.fromkeys(ids)), len(ids))
def test_repeat(self):
self.assertEqual(zip(xrange(3),repeat('a')),
self.assertEqual(lzip(xrange(3),repeat('a')),
[(0, 'a'), (1, 'a'), (2, 'a')])
self.assertEqual(list(repeat('a', 3)), ['a', 'a', 'a'])
self.assertEqual(take(3, repeat('a')), ['a', 'a', 'a'])
@ -320,7 +324,7 @@ class TestBasicOps(unittest.TestCase):
self.assertEqual(list(b), [])
a, b = tee(irange(n)) # test 100% interleaved
self.assertEqual(zip(a,b), zip(range(n),range(n)))
self.assertEqual(lzip(a,b), lzip(range(n), range(n)))
a, b = tee(irange(n)) # test 0% interleaved
self.assertEqual(list(a), range(n))
@ -601,8 +605,8 @@ class TestVariousIteratorArgs(unittest.TestCase):
def test_izip(self):
for s in ("123", "", range(1000), ('do', 1.2), xrange(2000,2200,5)):
for g in (G, I, Ig, S, L, R):
self.assertEqual(list(izip(g(s))), zip(g(s)))
self.assertEqual(list(izip(g(s), g(s))), zip(g(s), g(s)))
self.assertEqual(list(izip(g(s))), lzip(g(s)))
self.assertEqual(list(izip(g(s), g(s))), lzip(g(s), g(s)))
self.assertRaises(TypeError, izip, X(s))
self.assertRaises(TypeError, izip, N(s))
self.assertRaises(ZeroDivisionError, list, izip(E(s)))
@ -627,7 +631,7 @@ class TestVariousIteratorArgs(unittest.TestCase):
def test_starmap(self):
for s in (range(10), range(0), range(100), (7,11), xrange(20,50,5)):
for g in (G, I, Ig, S, L, R):
ss = zip(s, s)
ss = lzip(s, s)
self.assertEqual(list(starmap(operator.pow, g(ss))), map(operator.pow, g(s), g(s)))
self.assertRaises(TypeError, starmap, operator.pow, X(ss))
self.assertRaises(TypeError, starmap, operator.pow, N(ss))

2
Lib/test/test_tuple.py
View file

@ -61,7 +61,7 @@ class TupleTest(seq_tests.CommonTest):
base = range(N)
xp = [(i, j) for i in base for j in base]
inps = base + [(i, j) for i in base for j in xp] + \
[(i, j) for i in xp for j in base] + xp + zip(base)
[(i, j) for i in xp for j in base] + xp + list(zip(base))
collisions = len(inps) - len(set(map(hash, inps)))
self.assert_(collisions <= 15)

118
Python/bltinmodule.c
View file

@ -1855,116 +1855,32 @@ is a shortcut for issubclass(X, A) or issubclass(X, B) or ... (etc.).");
static PyObject*
builtin_zip(PyObject *self, PyObject *args)
{
PyObject *ret;
const Py_ssize_t itemsize = PySequence_Length(args);
Py_ssize_t i;
PyObject *itlist; /* tuple of iterators */
Py_ssize_t len; /* guess at result length */
PyObject *itertools = NULL, *izip = NULL, *result = NULL;
if (itemsize == 0)
return PyList_New(0);
/* args must be a tuple */
assert(PyTuple_Check(args));
/* Guess at result length: the shortest of the input lengths.
If some argument refuses to say, we refuse to guess too, lest
an argument like xrange(sys.maxint) lead us astray.*/
len = -1; /* unknown */
for (i = 0; i < itemsize; ++i) {
PyObject *item = PyTuple_GET_ITEM(args, i);
Py_ssize_t thislen = _PyObject_LengthHint(item);
if (thislen < 0) {
if (!PyErr_ExceptionMatches(PyExc_TypeError) &&
!PyErr_ExceptionMatches(PyExc_AttributeError)) {
return NULL;
}
PyErr_Clear();
len = -1;
break;
}
else if (len < 0 || thislen < len)
len = thislen;
}
/* allocate result list */
if (len < 0)
len = 10; /* arbitrary */
if ((ret = PyList_New(len)) == NULL)
itertools = PyImport_ImportModule("itertools");
if (itertools == NULL)
return NULL;
izip = PyObject_GetAttrString(itertools, "izip");
if (izip == NULL)
goto done;
/* obtain iterators */
itlist = PyTuple_New(itemsize);
if (itlist == NULL)
goto Fail_ret;
for (i = 0; i < itemsize; ++i) {
PyObject *item = PyTuple_GET_ITEM(args, i);
PyObject *it = PyObject_GetIter(item);
if (it == NULL) {
if (PyErr_ExceptionMatches(PyExc_TypeError))
PyErr_Format(PyExc_TypeError,
"zip argument #%zd must support iteration",
i+1);
goto Fail_ret_itlist;
}
PyTuple_SET_ITEM(itlist, i, it);
}
result = PyObject_Call(izip, args, NULL);
/* build result into ret list */
for (i = 0; ; ++i) {
int j;
PyObject *next = PyTuple_New(itemsize);
if (!next)
goto Fail_ret_itlist;
for (j = 0; j < itemsize; j++) {
PyObject *it = PyTuple_GET_ITEM(itlist, j);
PyObject *item = PyIter_Next(it);
if (!item) {
if (PyErr_Occurred()) {
Py_DECREF(ret);
ret = NULL;
}
Py_DECREF(next);
Py_DECREF(itlist);
goto Done;
}
PyTuple_SET_ITEM(next, j, item);
}
if (i < len)
PyList_SET_ITEM(ret, i, next);
else {
int status = PyList_Append(ret, next);
Py_DECREF(next);
++len;
if (status < 0)
goto Fail_ret_itlist;
}
}
Done:
if (ret != NULL && i < len) {
/* The list is too big. */
if (PyList_SetSlice(ret, i, len, NULL) < 0)
return NULL;
}
return ret;
Fail_ret_itlist:
Py_DECREF(itlist);
Fail_ret:
Py_DECREF(ret);
return NULL;
done:
Py_XDECREF(itertools);
Py_XDECREF(izip);
return result;
}
PyDoc_STRVAR(zip_doc,
"zip(seq1 [, seq2 [...]]) -> [(seq1[0], seq2[0] ...), (...)]\n\
"zip(it1 [, it2 [...]]) -> iter([(it1[0], it2[0] ...), ...])\n\
\n\
Return a list of tuples, where each tuple contains the i-th element\n\
from each of the argument sequences. The returned list is truncated\n\
in length to the length of the shortest argument sequence.");
Return an iterator yielding tuples, where each tuple contains the\n\
corresponding element from each of the argument iterables.\n\
The returned iterator ends when the shortest argument iterable is exhausted.\n\
NOTE: This is implemented using itertools.izip().");
static PyMethodDef builtin_methods[] = {