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stats/rng

src/stats/rng.tur
defn

rng-make

(rng-make [seed :int stream :int] :int)

create a new PCG32 stream seeded with seed.

Parameters
seed:int seed value; 0 uses a default fixed seed (PCG default)
stream:int stream discriminator; use different values for independent streams
Returns

:int opaque rng handle. Free with rng-free.

Example
(let [r (rng-make 42 1)]
    (rng-uniform r))   ; => deterministic float in [0,1)

Since: ST0

defn

rng-clone

(rng-clone [r :int] :int)

create an independent copy of rng r at the same state.

Parameters
r:int source rng handle
Returns

:int new rng handle at the same state. Free with rng-free.

Example
(let [a (rng-make 1 1)
        b (rng-clone a)]
    (= (rng-uniform a) (rng-uniform b)))  ; => true

Since: ST0

defn

rng-free

(rng-free [r :int] :void)

free a rng handle.

Parameters
r:int rng handle
Returns

:void

Example
(rng-free (rng-make 1 1))

Since: ST0

defn

rng-uint32

(rng-uint32 [r :int] :int)

draw a uniform 32-bit integer from [0, 2^32).

Parameters
r:int rng handle
Returns

:int value in [0, 2^32).

Example
(rng-uint32 (rng-make 1 1))  ; => some :int

Since: ST0

defn

rng-uint64

(rng-uint64 [r :int] :int)

draw a uniform 64-bit integer.

Parameters
r:int rng handle
Returns

:int 64-bit random value (sign bit may be set).

Since: ST0

defn

rng-uniform

(rng-uniform [r :int] :float)

draw a uniform float in [0, 1).

Parameters
r:int rng handle
Returns

:float in [0, 1).

Example
(rng-uniform (rng-make 42 1))

Since: ST0

defn

rng-uniform-range

(rng-uniform-range [r :int lo :float hi :float] :float)

draw a uniform float in [lo, hi).

Parameters
r:int rng handle
lo:float lower bound (inclusive)
hi:float upper bound (exclusive)
Returns

:float in [lo, hi).

Example
(rng-uniform-range r -1.0 1.0)

Since: ST0

defn

rng-int-range

(rng-int-range [r :int lo :int hi :int] :int)

draw a uniform integer in [lo, hi).

Parameters
r:int rng handle
lo:int lower bound (inclusive)
hi:int upper bound (exclusive)
Returns

:int in [lo, hi).

Example
(rng-int-range r 0 6)  ; => 0..5

Since: ST0

defn

rng-shuffle!

(rng-shuffle! [r :int indices :int] :void)

in-place Fisher-Yates shuffle of a cons list of :int indices.

Parameters
r:int rng handle
indicescons list of :int (modified in-place)
Returns

:void

Example
(let [lst (cons 0 (cons 1 (cons 2 0)))]
    (rng-shuffle! r lst))

Since: ST0

defn

rng-shuffled

(rng-shuffled [r :int indices :int] :int)

return a new shuffled copy of a cons list of :int.

Parameters
r:int rng handle
indicescons list of :int
Returns

New cons list of :int in shuffled order. Caller owns the new list.

Since: ST0

defn

rng-sample-indices

(rng-sample-indices [r :int n :int k :int with-replacement :int] :int)

sample k indices from [0, n) with or without replacement.

Parameters
r:int rng handle
n:int population size
k:int sample size
with-replacement:int 0 = without replacement, 1 = with replacement
Returns

cons list of :int (k indices in [0, n)). Caller frees.

Example
(rng-sample-indices r 100 10 0)  ; => 10 distinct indices

Since: ST0

defn

rng-sample

(rng-sample [r :int col :int n :int with-replacement :int] :int)

sample n rows from a float64 column, with or without replacement.

Parameters
r:int rng handle
col:int tur-frame float64 column handle
n:int number of rows to sample
with-replacement:int 0 = without, 1 = with
Returns

:int new float64 column of length n. Caller frees.

Since: ST0