Creates new Mersenne Twister based pseudorandom number generator with seed. When the argument seed is omitted, the generator is initialized with ::new_seed.
The argument seed is used to ensure repeatable sequences of random numbers between different runs of the program.
prng = Random.new(1234) [ prng.rand, prng.rand ] #=> [0.191519450378892, 0.622108771039832] [ prng.integer(10), prng.integer(1000) ] #=> [4, 664] prng = Random.new(1234) [ prng.rand, prng.rand ] #=> [0.191519450378892, 0.622108771039832]
static VALUE
random_init(int argc, VALUE *argv, VALUE obj)
{
VALUE vseed;
rb_random_t *rnd = get_rnd(obj);
if (argc == 0) {
vseed = random_seed();
}
else {
rb_scan_args(argc, argv, "01", &vseed);
}
rnd->seed = rand_init(&rnd->mt, vseed);
return obj;
}
Returns arbitrary value for seed.
static VALUE
random_seed(void)
{
unsigned int buf[DEFAULT_SEED_CNT];
fill_random_seed(buf);
return make_seed_value(buf);
}
Alias of _Random::DEFAULT.rand_.
static VALUE
random_s_rand(int argc, VALUE *argv, VALUE obj)
{
return random_rand(argc, argv, rb_Random_DEFAULT);
}
Seeds the pseudorandom number generator to the value of number. If
number is omitted, seeds the generator using a combination of the
time, the process id, and a sequence number. (This is also the behavior if
Kernel::rand is called without previously calling
srand, but without the sequence.) By setting the seed to a
known value, scripts can be made deterministic during testing. The previous
seed value is returned. Also see Kernel::rand.
static VALUE
rb_f_srand(int argc, VALUE *argv, VALUE obj)
{
VALUE seed, old;
rb_random_t *r = &default_rand;
rb_secure(4);
if (argc == 0) {
seed = random_seed();
}
else {
rb_scan_args(argc, argv, "01", &seed);
}
old = r->seed;
r->seed = rand_init(&r->mt, seed);
return old;
}
Returns true if the generators' states equal.
static VALUE
random_equal(VALUE self, VALUE other)
{
rb_random_t *r1, *r2;
if (rb_obj_class(self) != rb_obj_class(other)) return Qfalse;
r1 = get_rnd(self);
r2 = get_rnd(other);
if (!RTEST(rb_funcall2(r1->seed, rb_intern("=="), 1, &r2->seed))) return Qfalse;
if (memcmp(r1->mt.state, r2->mt.state, sizeof(r1->mt.state))) return Qfalse;
if ((r1->mt.next - r1->mt.state) != (r2->mt.next - r2->mt.state)) return Qfalse;
if (r1->mt.left != r2->mt.left) return Qfalse;
return Qtrue;
}
Returns a random binary string. The argument size specified the length of the result string.
static VALUE
random_bytes(VALUE obj, VALUE len)
{
return rb_random_bytes(obj, NUM2LONG(rb_to_int(len)));
}
When the argument is an Integer or a Bignum, it
returns a random integer greater than or equal to zero and less than the
argument. Unlike #rand, when the
argument is a negative integer or zero, it raises an ArgumentError.
When the argument is a Float, it returns a random floating
point number between 0.0 and max, including 0.0 and excluding
max.
When the argument limit is a Range, it returns a
random number where range.member?(number) == true.
prng.rand(5..9) #=> one of [5, 6, 7, 8, 9] prng.rand(5...9) #=> one of [5, 6, 7, 8] prng.rand(5.0..9.0) #=> between 5.0 and 9.0, including 9.0 prng.rand(5.0...9.0) #=> between 5.0 and 9.0, excluding 9.0
begin/end of the range have to have subtract and
add methods.
Otherwise, it raises an ArgumentError.
static VALUE
random_rand(int argc, VALUE *argv, VALUE obj)
{
rb_random_t *rnd = get_rnd(obj);
VALUE vmax, v;
if (argc == 0) {
return rb_float_new(genrand_real(&rnd->mt));
}
else if (argc != 1) {
rb_raise(rb_eArgError, "wrong number of arguments (%d for 0..1)", argc);
}
vmax = argv[0];
if (NIL_P(vmax)) {
v = Qnil;
}
else if (TYPE(vmax) != T_FLOAT && (v = rb_check_to_integer(vmax, "to_int"), !NIL_P(v))) {
v = rand_int(&rnd->mt, v, 1);
}
else if (v = rb_check_to_float(vmax), !NIL_P(v)) {
double max = float_value(v);
if (max > 0.0)
v = rb_float_new(max * genrand_real(&rnd->mt));
else
v = Qnil;
}
else if ((v = rand_range(&rnd->mt, vmax)) != Qfalse) {
/* nothing to do */
}
else {
v = Qnil;
(void)NUM2LONG(vmax);
}
if (NIL_P(v)) {
VALUE mesg = rb_str_new_cstr("invalid argument - ");
rb_str_append(mesg, rb_obj_as_string(argv[0]));
rb_exc_raise(rb_exc_new3(rb_eArgError, mesg));
}
return v;
}
Returns the seed of the generator.
static VALUE
random_get_seed(VALUE obj)
{
return get_rnd(obj)->seed;
}