Function PGARandomSampleInit

• Defined in File random.c

Function Documentation

void PGARandomSampleInit(PGAContext *ctx, PGASampleState *state, int k, int n)

Init random sampling of k out of n without replacement.

Description

Algorithm from [Vit87]. This is implemented as an iterator, i.e., this init method that initializes n and k and a function PGARandomNextSample() that returns the next sample index. The algorithm guarantees that sample indexes are returned sorted in index order. Note that the internal implementation variable CUTOFF is arbitrary and no measurements were performed – modern CPUs can probably iterate a lot when not accessing memory, so this can probably be set a lot higher.

Example

PGAContext *ctx;
PGASampleState state;
int s;

...
PGARandomSampleInit (ctx, &state, 3, 6);
s = PGARandomNextSample (&state);

Parameters

• ctx – context variable

• state – pointer to PGASampleState, needs to be allocated by caller

• k – k of the k out of n

• n – n of the k out of n

Returns

None