mirror of
https://github.com/golang/go
synced 2024-10-05 00:11:21 -06:00
199 lines
5.0 KiB
Go
199 lines
5.0 KiB
Go
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package rand implements pseudo-random number generators.
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package rand
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// A Source represents a source of uniformly-distributed
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// pseudo-random int64 values in the range [0, 1<<63).
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type Source interface {
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Int63() int64;
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Seed(seed int64);
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}
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// NewSource returns a new pseudo-random Source seeded with the given value.
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func NewSource(seed int64) Source {
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var rng rngSource;
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rng.Seed(seed);
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return &rng;
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}
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// A Rand is a source of random numbers.
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type Rand struct {
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src Source;
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}
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// New returns a new Rand that uses random values from src
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// to generate other random values.
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func New(src Source) *Rand {
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return &Rand{src};
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}
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// Seed uses the provided seed value to initialize the generator to a deterministic state.
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func (r *Rand) Seed(seed int64) {
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r.src.Seed(seed);
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}
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// Int63 returns a non-negative pseudo-random 63-bit integer as an int64.
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func (r *Rand) Int63() int64 {
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return r.src.Int63();
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}
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// Uint32 returns a pseudo-random 32-bit value as a uint32.
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func (r *Rand) Uint32() uint32 {
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return uint32(r.Int63() >> 31);
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}
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// Int31 returns a non-negative pseudo-random 31-bit integer as an int32.
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func (r *Rand) Int31() int32 {
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return int32(r.Int63() >> 32);
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}
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// Int returns a non-negative pseudo-random int.
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func (r *Rand) Int() int {
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u := uint(r.Int63());
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return int(u<<1>>1); // clear sign bit if int == int32
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}
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// Int63n returns, as an int64, a non-negative pseudo-random number in [0,n).
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func (r *Rand) Int63n(n int64) int64 {
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if n <= 0 {
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return 0;
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}
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max := int64((1<<63) - 1 - (1<<63)%uint64(n));
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v := r.Int63();
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for v > max {
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v = r.Int63();
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}
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return v%n;
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}
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// Int31n returns, as an int32, a non-negative pseudo-random number in [0,n).
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func (r *Rand) Int31n(n int32) int32 {
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return int32(r.Int63n(int64(n)));
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}
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// Intn returns, as an int, a non-negative pseudo-random number in [0,n).
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func (r *Rand) Intn(n int) int {
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return int(r.Int63n(int64(n)));
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}
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// Float64 returns, as a float64, a pseudo-random number in [0.0,1.0).
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func (r *Rand) Float64() float64 {
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return float64(r.Int63())/(1<<63);
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}
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// Float32 returns, as a float32, a pseudo-random number in [0.0,1.0).
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func (r *Rand) Float32() float32 {
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return float32(r.Float64());
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}
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// Float returns, as a float, a pseudo-random number in [0.0,1.0).
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func (r *Rand) Float() float {
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return float(r.Float64());
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}
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// Perm returns, as a slice of n ints, a pseudo-random permutation of the integers [0,n).
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func (r *Rand) Perm(n int) []int {
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m := make([]int, n);
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for i := 0; i < n; i++ {
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m[i] = i;
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}
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for i := 0; i < n; i++ {
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j := r.Intn(i+1);
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m[i], m[j] = m[j], m[i];
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}
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return m;
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}
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/*
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* Top-level convenience functions
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*/
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var globalRand = New(NewSource(1))
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// Seed uses the provided seed value to initialize the generator to a deterministic state.
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func Seed(seed int64) {
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globalRand.Seed(seed);
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}
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// Int63 returns a non-negative pseudo-random 63-bit integer as an int64.
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func Int63() int64 {
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return globalRand.Int63();
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}
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// Uint32 returns a pseudo-random 32-bit value as a uint32.
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func Uint32() uint32 {
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return globalRand.Uint32();
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}
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// Int31 returns a non-negative pseudo-random 31-bit integer as an int32.
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func Int31() int32 {
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return globalRand.Int31();
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}
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// Int returns a non-negative pseudo-random int.
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func Int() int {
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return globalRand.Int();
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}
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// Int63n returns, as an int64, a non-negative pseudo-random number in [0,n).
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func Int63n(n int64) int64 {
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return globalRand.Int63n(n);
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}
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// Int31n returns, as an int32, a non-negative pseudo-random number in [0,n).
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func Int31n(n int32) int32 {
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return globalRand.Int31n(n);
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}
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// Intn returns, as an int, a non-negative pseudo-random number in [0,n).
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func Intn(n int) int {
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return globalRand.Intn(n);
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}
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// Float64 returns, as a float64, a pseudo-random number in [0.0,1.0).
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func Float64() float64 {
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return globalRand.Float64();
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}
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// Float32 returns, as a float32, a pseudo-random number in [0.0,1.0).
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func Float32() float32 {
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return globalRand.Float32();
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}
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// Float returns, as a float, a pseudo-random number in [0.0,1.0).
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func Float() float {
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return globalRand.Float();
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}
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// Perm returns, as a slice of n ints, a pseudo-random permutation of the integers [0,n).
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func Perm(n int) []int {
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return globalRand.Perm(n);
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}
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// NormFloat64 returns a normally distributed float64 in the range
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// [-math.MaxFloat64, +math.MaxFloat64] with
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// standard normal distribution (mean = 0, stddev = 1).
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// To produce a different normal distribution, callers can
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// adjust the output using:
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//
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// sample = NormFloat64() * desiredStdDev + desiredMean
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//
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func NormFloat64() float64 {
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return globalRand.NormFloat64();
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}
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// ExpFloat64 returns an exponentially distributed float64 in the range
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// (0, +math.MaxFloat64] with an exponential distribution whose rate parameter
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// (lambda) is 1 and whose mean is 1/lambda (1).
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// To produce a distribution with a different rate parameter,
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// callers can adjust the output using:
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//
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// sample = ExpFloat64() / desiredRateParameter
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//
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func ExpFloat64() float64 {
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return globalRand.ExpFloat64();
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}
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