gh-125916: Allow functools.reduce() 'initial' to be a keyword argument (#125917)

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Sayandip Dutta 2024-11-12 18:41:58 +05:30 committed by GitHub
parent 6e3bb8a913
commit abb90ba46c
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8 changed files with 76 additions and 13 deletions

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@ -453,7 +453,7 @@ The :mod:`functools` module defines the following functions:
.. versionadded:: 3.4
.. function:: reduce(function, iterable[, initial], /)
.. function:: reduce(function, iterable, /[, initial])
Apply *function* of two arguments cumulatively to the items of *iterable*, from
left to right, so as to reduce the iterable to a single value. For example,
@ -468,7 +468,7 @@ The :mod:`functools` module defines the following functions:
initial_missing = object()
def reduce(function, iterable, initial=initial_missing, /):
def reduce(function, iterable, /, initial=initial_missing):
it = iter(iterable)
if initial is initial_missing:
value = next(it)
@ -481,6 +481,9 @@ The :mod:`functools` module defines the following functions:
See :func:`itertools.accumulate` for an iterator that yields all intermediate
values.
.. versionchanged:: next
*initial* is now supported as a keyword argument.
.. decorator:: singledispatch
Transform a function into a :term:`single-dispatch <single

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@ -320,6 +320,11 @@ functools
to reserve a place for positional arguments.
(Contributed by Dominykas Grigonis in :gh:`119127`.)
* Allow the *initial* parameter of :func:`functools.reduce` to be passed
as a keyword argument.
(Contributed by Sayandip Dutta in :gh:`125916`.)
getopt
------

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@ -236,7 +236,7 @@ _initial_missing = object()
def reduce(function, sequence, initial=_initial_missing):
"""
reduce(function, iterable[, initial], /) -> value
reduce(function, iterable, /[, initial]) -> value
Apply a function of two arguments cumulatively to the items of an iterable, from left to right.

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@ -1005,6 +1005,29 @@ class TestReduce:
d = {"one": 1, "two": 2, "three": 3}
self.assertEqual(self.reduce(add, d), "".join(d.keys()))
# test correctness of keyword usage of `initial` in `reduce`
def test_initial_keyword(self):
def add(x, y):
return x + y
self.assertEqual(
self.reduce(add, ['a', 'b', 'c'], ''),
self.reduce(add, ['a', 'b', 'c'], initial=''),
)
self.assertEqual(
self.reduce(add, [['a', 'c'], [], ['d', 'w']], []),
self.reduce(add, [['a', 'c'], [], ['d', 'w']], initial=[]),
)
self.assertEqual(
self.reduce(lambda x, y: x*y, range(2,8), 1),
self.reduce(lambda x, y: x*y, range(2,8), initial=1),
)
self.assertEqual(
self.reduce(lambda x, y: x*y, range(2,21), 1),
self.reduce(lambda x, y: x*y, range(2,21), initial=1),
)
self.assertRaises(TypeError, self.reduce, add, [0, 1], initial="")
self.assertEqual(self.reduce(42, "", initial="1"), "1") # func is never called with one item
@unittest.skipUnless(c_functools, 'requires the C _functools module')
class TestReduceC(TestReduce, unittest.TestCase):

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@ -485,6 +485,7 @@ Luke Dunstan
Virgil Dupras
Bruno Dupuis
Andy Dustman
Sayandip Dutta
Gary Duzan
Eugene Dvurechenski
Karmen Dykstra

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@ -0,0 +1,2 @@
Allow the *initial* parameter of :func:`functools.reduce` to be passed as a keyword argument.
Patch by Sayandip Dutta.

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@ -937,8 +937,8 @@ _functools.reduce
function as func: object
iterable as seq: object
initial as result: object = NULL
/
initial as result: object = NULL
Apply a function of two arguments cumulatively to the items of an iterable, from left to right.
@ -953,7 +953,7 @@ calculates ((((1 + 2) + 3) + 4) + 5).
static PyObject *
_functools_reduce_impl(PyObject *module, PyObject *func, PyObject *seq,
PyObject *result)
/*[clinic end generated code: output=30d898fe1267c79d input=d233c2670cba7f66]*/
/*[clinic end generated code: output=30d898fe1267c79d input=1511e9a8c38581ac]*/
{
PyObject *args, *it;

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@ -69,7 +69,7 @@ exit:
}
PyDoc_STRVAR(_functools_reduce__doc__,
"reduce($module, function, iterable, initial=<unrepresentable>, /)\n"
"reduce($module, function, iterable, /, initial=<unrepresentable>)\n"
"--\n"
"\n"
"Apply a function of two arguments cumulatively to the items of an iterable, from left to right.\n"
@ -82,30 +82,59 @@ PyDoc_STRVAR(_functools_reduce__doc__,
"calculates ((((1 + 2) + 3) + 4) + 5).");
#define _FUNCTOOLS_REDUCE_METHODDEF \
{"reduce", _PyCFunction_CAST(_functools_reduce), METH_FASTCALL, _functools_reduce__doc__},
{"reduce", _PyCFunction_CAST(_functools_reduce), METH_FASTCALL|METH_KEYWORDS, _functools_reduce__doc__},
static PyObject *
_functools_reduce_impl(PyObject *module, PyObject *func, PyObject *seq,
PyObject *result);
static PyObject *
_functools_reduce(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
_functools_reduce(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
{
PyObject *return_value = NULL;
#if defined(Py_BUILD_CORE) && !defined(Py_BUILD_CORE_MODULE)
#define NUM_KEYWORDS 1
static struct {
PyGC_Head _this_is_not_used;
PyObject_VAR_HEAD
PyObject *ob_item[NUM_KEYWORDS];
} _kwtuple = {
.ob_base = PyVarObject_HEAD_INIT(&PyTuple_Type, NUM_KEYWORDS)
.ob_item = { &_Py_ID(initial), },
};
#undef NUM_KEYWORDS
#define KWTUPLE (&_kwtuple.ob_base.ob_base)
#else // !Py_BUILD_CORE
# define KWTUPLE NULL
#endif // !Py_BUILD_CORE
static const char * const _keywords[] = {"", "", "initial", NULL};
static _PyArg_Parser _parser = {
.keywords = _keywords,
.fname = "reduce",
.kwtuple = KWTUPLE,
};
#undef KWTUPLE
PyObject *argsbuf[3];
Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 2;
PyObject *func;
PyObject *seq;
PyObject *result = NULL;
if (!_PyArg_CheckPositional("reduce", nargs, 2, 3)) {
args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser,
/*minpos*/ 2, /*maxpos*/ 3, /*minkw*/ 0, /*varpos*/ 0, argsbuf);
if (!args) {
goto exit;
}
func = args[0];
seq = args[1];
if (nargs < 3) {
goto skip_optional;
if (!noptargs) {
goto skip_optional_pos;
}
result = args[2];
skip_optional:
skip_optional_pos:
return_value = _functools_reduce_impl(module, func, seq, result);
exit:
@ -159,4 +188,4 @@ _functools__lru_cache_wrapper_cache_clear(PyObject *self, PyObject *Py_UNUSED(ig
return return_value;
}
/*[clinic end generated code: output=0c3df7e5131200b7 input=a9049054013a1b77]*/
/*[clinic end generated code: output=e6edcc01f0720daf input=a9049054013a1b77]*/