random

nimony/lib/std/random.nim

A fast, non-cryptographic pseudo-random number generator (xoroshiro128+).

Each proc has two forms: one taking an explicit Rand state, and one using a shared default generator. The default-generator procs are not thread-safe — give each thread its own Rand via initRand.

type Rand = object
  a0: uint64
  a1: uint64

func next(r: var Rand): uint64
Returns the next raw random uint64 and advances r.
proc skipRandomNumbers(r: var Rand)
Advances r by 2^64 steps — used to split a generator into non-overlapping subsequences for parallel work.
proc initRand(seed: int64): Rand
Creates a Rand seeded with seed. The same seed always yields the same sequence. seed == 0 is mapped to a fixed non-zero value.
proc rand(r: var Rand; max: int64): int64
Random integer in 0 .. max (inclusive) using r.
proc rand(max: int64): int64
Random integer in 0 .. max using the default generator.
proc rand(r: var Rand; max: float64): float64
Random float in 0.0 .. max using r.
proc rand(max: float64): float64
Random float in 0.0 .. max using the default generator.
proc rand(r: var Rand; x: HSlice): int64
Random integer in the inclusive range x using r.
proc rand(x: HSlice): int64
Random integer in the inclusive range x using the default generator.
proc rand(r: var Rand; x: HSlice): float64
Random float in the inclusive range x using r.
proc rand(x: HSlice): float64
Random float in the inclusive range x using the default generator.
proc sample(r: var Rand; a: openArray[T]): T
Returns a random element of a using r.
proc sample(a: openArray[T]): T
Returns a random element of a using the default generator.
proc shuffle(r: var Rand; x: var openArray[T])
Fisher-Yates shuffle of x in place using r.
proc shuffle(x: var openArray[T])
Shuffles x in place using the default generator.
proc randomize(seed: int64)
Reseeds the default generator with seed.