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GH-98363: Have batched() return tuples (GH-100118)

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Raymond Hettinger 2022-12-08 15:08:16 -06:00 • committed by GitHub
parent 41d4ac9da3
commit 35cc0ea736
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4 changed files with 40 additions and 38 deletions
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30
Modules/itertoolsmodule.c
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@ -56,11 +56,13 @@ static PyTypeObject pairwise_type;
/* batched object ************************************************************/
/* Note: The built-in zip() function includes a "strict" argument
that is needed because that function can silently truncate data
and there is no easy way for a user to detect that condition.
The same reasoning does not apply to batched() which never drops
data. Instead, it produces a shorter list which can be handled
as the user sees fit.
that was needed because that function would silently truncate data,
and there was no easy way for a user to detect the data loss.
The same reasoning does not apply to batched() which never drops data.
Instead, batched() produces a shorter tuple which can be handled
as the user sees fit. If requested, it would be reasonable to add
"fillvalue" support which had demonstrated value in zip_longest().
For now, the API is kept simple and clean.
*/
typedef struct {
@ -74,25 +76,25 @@ typedef struct {
itertools.batched.__new__ as batched_new
iterable: object
n: Py_ssize_t
Batch data into lists of length n. The last batch may be shorter than n.
Batch data into tuples of length n. The last batch may be shorter than n.
Loops over the input iterable and accumulates data into lists
Loops over the input iterable and accumulates data into tuples
up to size n. The input is consumed lazily, just enough to
fill a list. The result is yielded as soon as a batch is full
fill a batch. The result is yielded as soon as a batch is full
or when the input iterable is exhausted.
>>> for batch in batched('ABCDEFG', 3):
... print(batch)
...
['A', 'B', 'C']
['D', 'E', 'F']
['G']
('A', 'B', 'C')
('D', 'E', 'F')
('G',)
[clinic start generated code]*/
static PyObject *
batched_new_impl(PyTypeObject *type, PyObject *iterable, Py_ssize_t n)
/*[clinic end generated code: output=7ebc954d655371b6 input=f28fd12cb52365f0]*/
/*[clinic end generated code: output=7ebc954d655371b6 input=ffd70726927c5129]*/
{
PyObject *it;
batchedobject *bo;
@ -150,12 +152,12 @@ batched_next(batchedobject *bo)
if (it == NULL) {
return NULL;
}
result = PyList_New(n);
result = PyTuple_New(n);
if (result == NULL) {
return NULL;
}
iternextfunc iternext = *Py_TYPE(it)->tp_iternext;
PyObject **items = _PyList_ITEMS(result);
PyObject **items = _PyTuple_ITEMS(result);
for (i=0 ; i < n ; i++) {
item = iternext(it);
if (item == NULL) {