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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); }
Converts max to an integer using max1 = max.to_i.abs
.
If max is nil
the result is zero, returns a
pseudorandom floating point number greater than or equal to 0.0 and less
than 1.0. Otherwise, returns a pseudorandom integer greater than or equal
to zero and less than max1. Kernel::srand
may be used to
ensure repeatable sequences of random numbers between different runs of the
program. Ruby currently uses a modified Mersenne Twister with a period of
2**19937-1.
srand 1234 #=> 0 [ rand, rand ] #=> [0.191519450163469, 0.49766366626136] [ rand(10), rand(1000) ] #=> [6, 817] srand 1234 #=> 1234 [ rand, rand ] #=> [0.191519450163469, 0.49766366626136]
static VALUE rb_f_rand(int argc, VALUE *argv, VALUE obj) { VALUE vmax, r; struct MT *mt = default_mt(); if (argc == 0) goto zero_arg; rb_scan_args(argc, argv, "01", &vmax); if (NIL_P(vmax)) goto zero_arg; vmax = rb_to_int(vmax); if (vmax == INT2FIX(0) || NIL_P(r = rand_int(mt, vmax, 0))) { zero_arg: return DBL2NUM(genrand_real(mt)); } return r; }
Seeds the pseudorandom number generator to the value of number. If
number is omitted or zero, 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, beg = Qundef, v; int excl = 0; 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, vmax = 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 = range_values(vmax, &beg, &excl)) != Qfalse) { vmax = v; if (TYPE(vmax) != T_FLOAT && (v = rb_check_to_integer(vmax, "to_int"), !NIL_P(v))) { long max; vmax = v; v = Qnil; if (FIXNUM_P(vmax)) { fixnum: if ((max = FIX2LONG(vmax) - excl) >= 0) { unsigned long r = limited_rand(&rnd->mt, (unsigned long)max); v = ULONG2NUM(r); } } else if (BUILTIN_TYPE(vmax) == T_BIGNUM && RBIGNUM_SIGN(vmax) && !rb_bigzero_p(vmax)) { vmax = excl ? rb_big_minus(vmax, INT2FIX(1)) : rb_big_norm(vmax); if (FIXNUM_P(vmax)) { excl = 0; goto fixnum; } v = limited_big_rand(&rnd->mt, RBIGNUM(vmax)); } } else if (v = rb_check_to_float(vmax), !NIL_P(v)) { double max = float_value(v), r; v = Qnil; if (max > 0.0) { if (excl) { r = genrand_real(&rnd->mt); } else { r = genrand_real2(&rnd->mt); } v = rb_float_new(r * max); } else if (max == 0.0 && !excl) { v = rb_float_new(0.0); } } } else { v = Qnil; 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)); } if (beg == Qundef) return v; if (FIXNUM_P(beg) && FIXNUM_P(v)) { long x = FIX2LONG(beg) + FIX2LONG(v); return LONG2NUM(x); } switch (TYPE(v)) { case T_BIGNUM: return rb_big_plus(v, beg); case T_FLOAT: { VALUE f = rb_check_to_float(beg); if (!NIL_P(f)) { RFLOAT_VALUE(v) += RFLOAT_VALUE(f); return v; } } default: return rb_funcall2(beg, id_plus, 1, &v); } }