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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

34
Lib/test/test_itertools.py
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@ -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))