Package rand
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func ExpFloat64 ¶
func ExpFloat64() float64
ExpFloat64 returns an exponentially distributed float64 in the range (0, +[math.MaxFloat64]] with an exponential distribution whose rate parameter (lambda) is 1 and whose mean is 1/lambda (1) from the default Source. To produce a distribution with a different rate parameter, callers can adjust the output using:
sample = ExpFloat64() / desiredRateParameter
func Float32 ¶
func Float32() float32
Float32 returns, as a float32, a pseudo-random number in the half-open interval [0.0,1.0) from the default Source.
func Float64 ¶
func Float64() float64
Float64 returns, as a float64, a pseudo-random number in the half-open interval [0.0,1.0) from the default Source.
func Int ¶
func Int() int
Int returns a non-negative pseudo-random int from the default Source.
func Int31 ¶
func Int31() int32
Int31 returns a non-negative pseudo-random 31-bit integer as an int32 from the default Source.
func Int31n ¶
func Int31n(n int32) int32
Int31n returns, as an int32, a non-negative pseudo-random number in the half-open interval [0,n) from the default Source. It panics if n <= 0.
func Int63 ¶
func Int63() int64
Int63 returns a non-negative pseudo-random 63-bit integer as an int64 from the default Source.
func Int63n ¶
func Int63n(n int64) int64
Int63n returns, as an int64, a non-negative pseudo-random number in the half-open interval [0,n) from the default Source. It panics if n <= 0.
func Intn ¶
func Intn(n int) int
Intn returns, as an int, a non-negative pseudo-random number in the half-open interval [0,n) from the default Source. It panics if n <= 0.
▸ Example
func NormFloat64 ¶
func NormFloat64() float64
NormFloat64 returns a normally distributed float64 in the range [-math.MaxFloat64, +[math.MaxFloat64]] with standard normal distribution (mean = 0, stddev = 1) from the default Source. To produce a different normal distribution, callers can adjust the output using:
sample = NormFloat64() * desiredStdDev + desiredMean
func Perm ¶
func Perm(n int) []int
Perm returns, as a slice of n ints, a pseudo-random permutation of the integers in the half-open interval [0,n) from the default Source.
▸ Example
func Read ¶ 1.6
func Read(p []byte) (n int, err error)
Read generates len(p) random bytes from the default Source and writes them into p. It always returns len(p) and a nil error. Read, unlike the Rand.Read method, is safe for concurrent use.
Deprecated: For almost all use cases, crypto/rand.Read is more appropriate. If a deterministic source is required, use math/rand/v2.ChaCha8.Read.
func Seed ¶
func Seed(seed int64)
Seed uses the provided seed value to initialize the default Source to a deterministic state. Seed values that have the same remainder when divided by 2³¹-1 generate the same pseudo-random sequence. Seed, unlike the Rand.Seed method, is safe for concurrent use.
If Seed is not called, the generator is seeded randomly at program startup.
Prior to Go 1.20, the generator was seeded like Seed(1) at program startup. To force the old behavior, call Seed(1) at program startup. Alternately, set GODEBUG=randautoseed=0 in the environment before making any calls to functions in this package.
Deprecated: As of Go 1.20 there is no reason to call Seed with a random value. Programs that call Seed with a known value to get a specific sequence of results should use New(NewSource(seed)) to obtain a local random generator.
func Shuffle ¶ 1.10
func Shuffle(n int, swap func(i, j int))
Shuffle pseudo-randomizes the order of elements using the default Source. n is the number of elements. Shuffle panics if n < 0. swap swaps the elements with indexes i and j.
▸ Example
▸ Example (SlicesInUnison)
func Uint32 ¶
func Uint32() uint32
Uint32 returns a pseudo-random 32-bit value as a uint32 from the default Source.
func Uint64 ¶ 1.8
func Uint64() uint64
Uint64 returns a pseudo-random 64-bit value as a uint64 from the default Source.
type Rand ¶
A Rand is a source of random numbers.
type Rand struct {
// contains filtered or unexported fields
}
func New ¶
func New(src Source) *Rand
New returns a new Rand that uses random values from src to generate other random values.
func (*Rand) ExpFloat64 ¶
func (r *Rand) ExpFloat64() float64
ExpFloat64 returns an exponentially distributed float64 in the range (0, +[math.MaxFloat64]] with an exponential distribution whose rate parameter (lambda) is 1 and whose mean is 1/lambda (1). To produce a distribution with a different rate parameter, callers can adjust the output using:
sample = ExpFloat64() / desiredRateParameter
func (*Rand) Float32 ¶
func (r *Rand) Float32() float32
Float32 returns, as a float32, a pseudo-random number in the half-open interval [0.0,1.0).
func (*Rand) Float64 ¶
func (r *Rand) Float64() float64
Float64 returns, as a float64, a pseudo-random number in the half-open interval [0.0,1.0).
func (*Rand) Int ¶
func (r *Rand) Int() int
Int returns a non-negative pseudo-random int.
func (*Rand) Int31 ¶
func (r *Rand) Int31() int32
Int31 returns a non-negative pseudo-random 31-bit integer as an int32.
func (*Rand) Int31n ¶
func (r *Rand) Int31n(n int32) int32
Int31n returns, as an int32, a non-negative pseudo-random number in the half-open interval [0,n). It panics if n <= 0.
func (*Rand) Int63 ¶
func (r *Rand) Int63() int64
Int63 returns a non-negative pseudo-random 63-bit integer as an int64.
func (*Rand) Int63n ¶
func (r *Rand) Int63n(n int64) int64
Int63n returns, as an int64, a non-negative pseudo-random number in the half-open interval [0,n). It panics if n <= 0.
func (*Rand) Intn ¶
func (r *Rand) Intn(n int) int
Intn returns, as an int, a non-negative pseudo-random number in the half-open interval [0,n). It panics if n <= 0.
func (*Rand) NormFloat64 ¶
func (r *Rand) NormFloat64() float64
NormFloat64 returns a normally distributed float64 in the range -math.MaxFloat64 through +[math.MaxFloat64] inclusive, with standard normal distribution (mean = 0, stddev = 1). To produce a different normal distribution, callers can adjust the output using:
sample = NormFloat64() * desiredStdDev + desiredMean
func (*Rand) Perm ¶
func (r *Rand) Perm(n int) []int
Perm returns, as a slice of n ints, a pseudo-random permutation of the integers in the half-open interval [0,n).
func (*Rand) Read ¶ 1.6
func (r *Rand) Read(p []byte) (n int, err error)
Read generates len(p) random bytes and writes them into p. It always returns len(p) and a nil error. Read should not be called concurrently with any other Rand method.
func (*Rand) Seed ¶
func (r *Rand) Seed(seed int64)
Seed uses the provided seed value to initialize the generator to a deterministic state. Seed should not be called concurrently with any other Rand method.
func (*Rand) Shuffle ¶ 1.10
func (r *Rand) Shuffle(n int, swap func(i, j int))
Shuffle pseudo-randomizes the order of elements. n is the number of elements. Shuffle panics if n < 0. swap swaps the elements with indexes i and j.
func (*Rand) Uint32 ¶
func (r *Rand) Uint32() uint32
Uint32 returns a pseudo-random 32-bit value as a uint32.
func (*Rand) Uint64 ¶ 1.8
func (r *Rand) Uint64() uint64
Uint64 returns a pseudo-random 64-bit value as a uint64.
type Source ¶
A Source represents a source of uniformly-distributed pseudo-random int64 values in the range [0, 1<<63).
A Source is not safe for concurrent use by multiple goroutines.
type Source interface {
Int63() int64
Seed(seed int64)
}
func NewSource ¶
func NewSource(seed int64) Source
NewSource returns a new pseudo-random Source seeded with the given value. Unlike the default Source used by top-level functions, this source is not safe for concurrent use by multiple goroutines. The returned Source implements Source64.
type Source64 ¶ 1.8
A Source64 is a Source that can also generate uniformly-distributed pseudo-random uint64 values in the range [0, 1<<64) directly. If a Rand r's underlying Source s implements Source64, then r.Uint64 returns the result of one call to s.Uint64 instead of making two calls to s.Int63.
type Source64 interface {
Source
Uint64() uint64
}
type Zipf ¶
A Zipf generates Zipf distributed variates.
type Zipf struct {
// contains filtered or unexported fields
}
func NewZipf ¶
func NewZipf(r *Rand, s float64, v float64, imax uint64) *Zipf
NewZipf returns a Zipf variate generator. The generator generates values k ∈ [0, imax] such that P(k) is proportional to (v + k) ** (-s). Requirements: s > 1 and v >= 1.
func (*Zipf) Uint64 ¶
func (z *Zipf) Uint64() uint64
Uint64 returns a value drawn from the Zipf distribution described by the Zipf object.