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Remove defunct parts of the random module

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Raymond Hettinger 2008-01-13 23:40:30 +00:00
parent f7ec7a81a5
commit 28de64fd0f
6 changed files with 32 additions and 360 deletions
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69
Modules/_randommodule.c
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@ -369,72 +369,6 @@ random_setstate(RandomObject *self, PyObject *state)
return Py_None;
}
/*
Jumpahead should be a fast way advance the generator n-steps ahead, but
lacking a formula for that, the next best is to use n and the existing
state to create a new state far away from the original.
The generator uses constant spaced additive feedback, so shuffling the
state elements ought to produce a state which would not be encountered
(in the near term) by calls to random(). Shuffling is normally
implemented by swapping the ith element with another element ranging
from 0 to i inclusive. That allows the element to have the possibility
of not being moved. Since the goal is to produce a new, different
state, the swap element is ranged from 0 to i-1 inclusive. This assures
that each element gets moved at least once.
To make sure that consecutive calls to jumpahead(n) produce different
states (even in the rare case of involutory shuffles), i+1 is added to
each element at position i. Successive calls are then guaranteed to
have changing (growing) values as well as shuffled positions.
Finally, the self->index value is set to N so that the generator itself
kicks in on the next call to random(). This assures that all results
have been through the generator and do not just reflect alterations to
the underlying state.
*/
static PyObject *
random_jumpahead(RandomObject *self, PyObject *n)
{
long i, j;
PyObject *iobj;
PyObject *remobj;
unsigned long *mt, tmp;
if (!PyLong_Check(n)) {
PyErr_Format(PyExc_TypeError, "jumpahead requires an "
"integer, not '%s'",
Py_TYPE(n)->tp_name);
return NULL;
}
mt = self->state;
for (i = N-1; i > 1; i--) {
iobj = PyLong_FromLong(i);
if (iobj == NULL)
return NULL;
remobj = PyNumber_Remainder(n, iobj);
Py_DECREF(iobj);
if (remobj == NULL)
return NULL;
j = PyLong_AsLong(remobj);
Py_DECREF(remobj);
if (j == -1L && PyErr_Occurred())
return NULL;
tmp = mt[i];
mt[i] = mt[j];
mt[j] = tmp;
}
for (i = 0; i < N; i++)
mt[i] += i+1;
self->index = N;
Py_INCREF(Py_None);
return Py_None;
}
static PyObject *
random_getrandbits(RandomObject *self, PyObject *args)
{
@ -506,9 +440,6 @@ static PyMethodDef random_methods[] = {
PyDoc_STR("getstate() -> tuple containing the current state.")},
{"setstate", (PyCFunction)random_setstate, METH_O,
PyDoc_STR("setstate(state) -> None. Restores generator state.")},
{"jumpahead", (PyCFunction)random_jumpahead, METH_O,
PyDoc_STR("jumpahead(int) -> None. Create new state from "
"existing state and integer.")},
{"getrandbits", (PyCFunction)random_getrandbits, METH_VARARGS,
PyDoc_STR("getrandbits(k) -> x. Generates a long int with "
"k random bits.")},