Replace map(None, *iterables) with zip(*iterables).

4 files changed, 11 insertions, 35 deletions

diff --git a/Lib/heapq.py b/Lib/heapq.py
index f3d0669..48697f6 100644
--- a/Lib/heapq.py
+++ b/Lib/heapq.py
@@ -351,7 +351,8 @@ def nsmallest(n, iterable, key=None):
     Equivalent to:  sorted(iterable, key=key)[:n]
     """
     in1, in2 = tee(iterable)
-    it = izip(map(key, in1), count(), in2)                  # decorate
+    keys = in1 if key is None else map(key, in1)
+    it = izip(keys, count(), in2)                           # decorate
     result = _nsmallest(n, it)
     return list(map(itemgetter(2), result))                 # undecorate
 
@@ -362,7 +363,8 @@ def nlargest(n, iterable, key=None):
     Equivalent to:  sorted(iterable, key=key, reverse=True)[:n]
     """
     in1, in2 = tee(iterable)
-    it = izip(map(key, in1), map(neg, count()), in2)        # decorate
+    keys = in1 if key is None else map(key, in1)
+    it = izip(keys, map(neg, count()), in2)                 # decorate
     result = _nlargest(n, it)
     return list(map(itemgetter(2), result))                 # undecorate
 
diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index 2718bbf..e6ded81 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -1100,18 +1100,6 @@ class BuiltinTest(unittest.TestCase):
 
     def test_map(self):
         self.assertEqual(
-            list(map(None, 'hello')),
-            [('h',), ('e',), ('l',), ('l',), ('o',)]
-        )
-        self.assertEqual(
-            list(map(None, 'abcd', 'efg')),
-            [('a', 'e'), ('b', 'f'), ('c', 'g')]
-        )
-        self.assertEqual(
-            list(map(None, range(3))),
-            [(0,), (1,), (2,)]
-        )
-        self.assertEqual(
             list(map(lambda x: x*x, range(1,4))),
             [1, 4, 9]
         )
@@ -1146,17 +1134,9 @@ class BuiltinTest(unittest.TestCase):
             [1+4+1, 3+9+1, 7+2+0]
         )
         self.assertEqual(
-            list(map(None, Squares(10))),
-            [(0,), (1,), (4,), (9,), (16,), (25,), (36,), (49,), (64,), (81,)]
-        )
-        self.assertEqual(
             list(map(int, Squares(10))),
             [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
         )
-        self.assertEqual(
-            list(map(None, Squares(3), Squares(2))),
-            [(0,0), (1,1)]
-        )
         def Max(a, b):
             if a is None:
                 return b
@@ -1169,7 +1149,6 @@ class BuiltinTest(unittest.TestCase):
         )
         self.assertRaises(TypeError, map)
         self.assertRaises(TypeError, map, lambda x: x, 42)
-        self.assertEqual(list(map(None, [42])), [(42,)])
         class BadSeq:
             def __iter__(self):
                 raise ValueError
diff --git a/Lib/test/test_iter.py b/Lib/test/test_iter.py
index 07a3bf2..d861dcd 100644
--- a/Lib/test/test_iter.py
+++ b/Lib/test/test_iter.py
@@ -382,13 +382,10 @@ class TestCase(unittest.TestCase):
 
     # Test map()'s use of iterators.
     def test_builtin_map(self):
-        self.assertEqual(list(map(None, SequenceClass(5))),
-                         [(0,), (1,), (2,), (3,), (4,)])
         self.assertEqual(list(map(lambda x: x+1, SequenceClass(5))),
                          list(range(1, 6)))
 
         d = {"one": 1, "two": 2, "three": 3}
-        self.assertEqual(list(map(None, d)), [(k,) for k in d])
         self.assertEqual(list(map(lambda k, d=d: (k, d[k]), d)),
                          list(d.items()))
         dkeys = list(d.keys())
@@ -396,11 +393,6 @@ class TestCase(unittest.TestCase):
                      i,
                      i < len(d) and dkeys[i] or None)
                     for i in range(3)]
-        self.assertEqual(list(map(None,
-                                  d,
-                                  SequenceClass(5),
-                                  iter(d.keys()))),
-                         expected)
 
         f = open(TESTFN, "w")
         try:
diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py
index 4c0af07..ae5eb90 100644
--- a/Lib/test/test_itertools.py
+++ b/Lib/test/test_itertools.py
@@ -236,7 +236,7 @@ class TestBasicOps(unittest.TestCase):
         self.assertEqual(list(izip_longest('abcdef')), list(zip('abcdef')))
 
         self.assertEqual(list(izip_longest('abc', 'defg', **{})),
-                         list(map(None, list('abc')+[None], 'defg'))) # empty keyword dict
+                         list(izip(list('abc')+[None], 'defg'))) # empty keyword dict
         self.assertRaises(TypeError, izip_longest, 3)
         self.assertRaises(TypeError, izip_longest, range(3), 3)
 
@@ -281,14 +281,17 @@ class TestBasicOps(unittest.TestCase):
     def test_imap(self):
         self.assertEqual(list(imap(operator.pow, range(3), range(1,7))),
                          [0**1, 1**2, 2**3])
-        self.assertEqual(list(imap(None, 'abc', range(5))),
+        def tupleize(*args):
+            return args
+        self.assertEqual(list(imap(tupleize, 'abc', range(5))),
                          [('a',0),('b',1),('c',2)])
-        self.assertEqual(list(imap(None, 'abc', count())),
+        self.assertEqual(list(imap(tupleize, 'abc', count())),
                          [('a',0),('b',1),('c',2)])
-        self.assertEqual(take(2,imap(None, 'abc', count())),
+        self.assertEqual(take(2,imap(tupleize, 'abc', count())),
                          [('a',0),('b',1)])
         self.assertEqual(list(imap(operator.pow, [])), [])
         self.assertRaises(TypeError, imap)
+        self.assertRaises(TypeError, list, imap(None, range(3), range(3)))
         self.assertRaises(TypeError, imap, operator.neg)
         self.assertRaises(TypeError, next, imap(10, range(5)))
         self.assertRaises(ValueError, next, imap(errfunc, [4], [5]))