Kill reduce(). A coproduction of John Reese, Jacques Frechet, and Alex M.

Lib/csv.py

@@ -221,12 +221,10 @@ class Sniffer:
             if m[n]:
                 spaces += 1
 
-        quotechar = reduce(lambda a, b, quotes = quotes:
-                           (quotes[a] > quotes[b]) and a or b, quotes.keys())
+        quotechar = max(quotes, key=quotes.get)
 
         if delims:
-            delim = reduce(lambda a, b, delims = delims:
-                           (delims[a] > delims[b]) and a or b, delims.keys())
+            delim = max(delims, key=delims.get)
             skipinitialspace = delims[delim] == spaces
             if delim == '\n': # most likely a file with a single column
                 delim = ''
@@ -285,14 +283,12 @@ class Sniffer:
                     continue
                 # get the mode of the frequencies
                 if len(items) > 1:
-                    modes[char] = reduce(lambda a, b: a[1] > b[1] and a or b,
-                                         items)
+                    modes[char] = max(items, key=lambda x: x[1])
                     # adjust the mode - subtract the sum of all
                     # other frequencies
                     items.remove(modes[char])
                     modes[char] = (modes[char][0], modes[char][1]
-                                   - reduce(lambda a, b: (0, a[1] + b[1]),
-                                            items)[1])
+                                   - sum(item[1] for item in items))
                 else:
                     modes[char] = items[0]
 

Lib/difflib.py

@@ -652,8 +652,7 @@ class SequenceMatcher:
         1.0
         """
 
-        matches = reduce(lambda sum, triple: sum + triple[-1],
-                         self.get_matching_blocks(), 0)
+        matches = sum(triple[-1] for triple in self.get_matching_blocks())
         return _calculate_ratio(matches, len(self.a) + len(self.b))
 
     def quick_ratio(self):

Lib/idlelib/AutoCompleteWindow.py

@@ -335,10 +335,8 @@ class AutoCompleteWindow:
             self.userwantswindow = True
             return
 
-        elif reduce(lambda x, y: x or y,
-                    [keysym.find(s) != -1 for s in ("Shift", "Control", "Alt",
-                                                    "Meta", "Command", "Option")
-                     ]):
+        elif any(s in keysym for s in ("Shift", "Control", "Alt",
+                                       "Meta", "Command", "Option")):
             # A modifier key, so ignore
             return
 

Lib/idlelib/MultiCall.py

@@ -106,24 +106,26 @@ class _SimpleBinder:
 # _state_subsets gives for each combination of modifiers, or *state*,
 # a list of the states which are a subset of it. This list is ordered by the
 # number of modifiers is the state - the most specific state comes first.
+# XXX rewrite without overusing functional primitives :-)
 _states = range(1 << len(_modifiers))
-_state_names = [reduce(lambda x, y: x + y,
-                       [_modifiers[i][0]+'-' for i in range(len(_modifiers))
-                        if (1 << i) & s],
-                       "")
+_state_names = [''.join(m[0]+'-'
+                        for i, m in enumerate(_modifiers)
+                        if (1 << i) & s)
                 for s in _states]
 _state_subsets = map(lambda i: filter(lambda j: not (j & (~i)), _states),
-                      _states)
+                     _states)
 for l in _state_subsets:
     l.sort(lambda a, b, nummod = lambda x: len(filter(lambda i: (1<<i) & x,
                                                       range(len(_modifiers)))):
            nummod(b) - nummod(a))
 # _state_codes gives for each state, the portable code to be passed as mc_state
-_state_codes = [reduce(lambda x, y: x | y,
-                       [_modifier_masks[i] for i in range(len(_modifiers))
-                        if (1 << i) & s],
-                       0)
-                for s in _states]
+_state_codes = []
+for s in _states:
+    r = 0
+    for i in range(len(_modifiers)):
+        if (1 << i) & s:
+            r |= _modifier_masks[i]
+    _state_codes.append(r)
 
 class _ComplexBinder:
     # This class binds many functions, and only unbinds them when it is deleted.

Lib/test/test_builtin.py

@@ -1393,32 +1393,6 @@ class BuiltinTest(unittest.TestCase):
         self.assertRaises(OverflowError, range, -sys.maxint, sys.maxint)
         self.assertRaises(OverflowError, range, 0, 2*sys.maxint)
 
-    def test_reduce(self):
-        self.assertEqual(reduce(lambda x, y: x+y, ['a', 'b', 'c'], ''), 'abc')
-        self.assertEqual(
-            reduce(lambda x, y: x+y, [['a', 'c'], [], ['d', 'w']], []),
-            ['a','c','d','w']
-        )
-        self.assertEqual(reduce(lambda x, y: x*y, range(2,8), 1), 5040)
-        self.assertEqual(
-            reduce(lambda x, y: x*y, range(2,21), 1L),
-            2432902008176640000L
-        )
-        self.assertEqual(reduce(lambda x, y: x+y, Squares(10)), 285)
-        self.assertEqual(reduce(lambda x, y: x+y, Squares(10), 0), 285)
-        self.assertEqual(reduce(lambda x, y: x+y, Squares(0), 0), 0)
-        self.assertRaises(TypeError, reduce)
-        self.assertRaises(TypeError, reduce, 42, 42)
-        self.assertRaises(TypeError, reduce, 42, 42, 42)
-        self.assertEqual(reduce(42, "1"), "1") # func is never called with one item
-        self.assertEqual(reduce(42, "", "1"), "1") # func is never called with one item
-        self.assertRaises(TypeError, reduce, 42, (42, 42))
-
-        class BadSeq:
-            def __getitem__(self, index):
-                raise ValueError
-        self.assertRaises(ValueError, reduce, 42, BadSeq())
-
     def test_reload(self):
         import marshal
         reload(marshal)

Lib/test/test_iter.py

@@ -498,19 +498,6 @@ class TestCase(unittest.TestCase):
             for y in NoGuessLen5(), Guess3Len5(), Guess30Len5():
                 self.assertEqual(zip(x, y), expected)
 
-    # Test reduces()'s use of iterators.
-    def test_builtin_reduce(self):
-        from operator import add
-        self.assertEqual(reduce(add, SequenceClass(5)), 10)
-        self.assertEqual(reduce(add, SequenceClass(5), 42), 52)
-        self.assertRaises(TypeError, reduce, add, SequenceClass(0))
-        self.assertEqual(reduce(add, SequenceClass(0), 42), 42)
-        self.assertEqual(reduce(add, SequenceClass(1)), 0)
-        self.assertEqual(reduce(add, SequenceClass(1), 42), 42)
-
-        d = {"one": 1, "two": 2, "three": 3}
-        self.assertEqual(reduce(add, d), "".join(d.keys()))
-
     # This test case will be removed if we don't have Unicode
     def test_unicode_join_endcase(self):
 

Lib/test/test_random.py

@@ -77,7 +77,9 @@ class TestBasicOps(unittest.TestCase):
         pop = range(n)
         trials = 10000  # large num prevents false negatives without slowing normal case
         def factorial(n):
-            return reduce(int.__mul__, xrange(1, n), 1)
+            if n == 0:
+                return 1
+            return n * factorial(n - 1)
         for k in xrange(n):
             expected = factorial(n) // factorial(n-k)
             perms = {}

Python/bltinmodule.c

@@ -1597,80 +1597,6 @@ For example, range(4) returns [0, 1, 2, 3].  The end point is omitted!\n\
 These are exactly the valid indices for a list of 4 elements.");
 
 
-static PyObject *
-builtin_reduce(PyObject *self, PyObject *args)
-{
-	PyObject *seq, *func, *result = NULL, *it;
-
-	if (!PyArg_UnpackTuple(args, "reduce", 2, 3, &func, &seq, &result))
-		return NULL;
-	if (result != NULL)
-		Py_INCREF(result);
-
-	it = PyObject_GetIter(seq);
-	if (it == NULL) {
-		PyErr_SetString(PyExc_TypeError,
-		    "reduce() arg 2 must support iteration");
-		Py_XDECREF(result);
-		return NULL;
-	}
-
-	if ((args = PyTuple_New(2)) == NULL)
-		goto Fail;
-
-	for (;;) {
-		PyObject *op2;
-
-		if (args->ob_refcnt > 1) {
-			Py_DECREF(args);
-			if ((args = PyTuple_New(2)) == NULL)
-				goto Fail;
-		}
-
-		op2 = PyIter_Next(it);
-		if (op2 == NULL) {
-			if (PyErr_Occurred())
-				goto Fail;
- 			break;
-		}
-
-		if (result == NULL)
-			result = op2;
-		else {
-			PyTuple_SetItem(args, 0, result);
-			PyTuple_SetItem(args, 1, op2);
-			if ((result = PyEval_CallObject(func, args)) == NULL)
-				goto Fail;
-		}
-	}
-
-	Py_DECREF(args);
-
-	if (result == NULL)
-		PyErr_SetString(PyExc_TypeError,
-			   "reduce() of empty sequence with no initial value");
-
-	Py_DECREF(it);
-	return result;
-
-Fail:
-	Py_XDECREF(args);
-	Py_XDECREF(result);
-	Py_DECREF(it);
-	return NULL;
-}
-
-PyDoc_STRVAR(reduce_doc,
-"reduce(function, sequence[, initial]) -> value\n\
-\n\
-Apply a function of two arguments cumulatively to the items of a sequence,\n\
-from left to right, so as to reduce the sequence to a single value.\n\
-For example, reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) calculates\n\
-((((1+2)+3)+4)+5).  If initial is present, it is placed before the items\n\
-of the sequence in the calculation, and serves as a default when the\n\
-sequence is empty.");
-
-
 static PyObject *
 builtin_reload(PyObject *self, PyObject *v)
 {
@@ -2071,7 +1997,6 @@ static PyMethodDef builtin_methods[] = {
  	{"ord",		builtin_ord,        METH_O, ord_doc},
  	{"pow",		builtin_pow,        METH_VARARGS, pow_doc},
  	{"range",	builtin_range,      METH_VARARGS, range_doc},
- 	{"reduce",	builtin_reduce,     METH_VARARGS, reduce_doc},
  	{"reload",	builtin_reload,     METH_O, reload_doc},
  	{"repr",	builtin_repr,       METH_O, repr_doc},
  	{"round",	(PyCFunction)builtin_round,      METH_VARARGS | METH_KEYWORDS, round_doc},

Tools/i18n/pygettext.py

@@ -462,12 +462,10 @@ class TokenEater:
             rentries = reverse[rkey]
             rentries.sort()
             for k, v in rentries:
-                isdocstring = 0
                 # If the entry was gleaned out of a docstring, then add a
                 # comment stating so.  This is to aid translators who may wish
                 # to skip translating some unimportant docstrings.
-                if reduce(operator.__add__, v.values()):
-                    isdocstring = 1
+                isdocstring = any(v.values())
                 # k is the message string, v is a dictionary-set of (filename,
                 # lineno) tuples.  We want to sort the entries in v first by
                 # file name and then by line number.

Tools/pybench/pybench.py

@@ -370,7 +370,7 @@ class Test:
         if runs == 0:
             return 0.0, 0.0, 0.0, 0.0
         min_time = min(self.times)
-        total_time = reduce(operator.add, self.times, 0.0)
+        total_time = sum(self.times)
         avg_time = total_time / float(runs)
         operation_avg = total_time / float(runs
                                            * self.rounds
@@ -570,7 +570,7 @@ class Benchmark:
         if runs == 0:
             return 0.0, 0.0
         min_time = min(self.roundtimes)
-        total_time = reduce(operator.add, self.roundtimes, 0.0)
+        total_time = sum(self.roundtimes)
         avg_time = total_time / float(runs)
         max_time = max(self.roundtimes)
         return (min_time, avg_time, max_time)