partialShuffle

fnRange partialShuffle(Range, RandomGen)(Range r, in size_t n, ref RandomGen gen) if (isRandomAccessRange!Range && isUniformRNG!RandomGen)

Partially shuffles the elements of r such that upon returning r[0 .. n] is a random subset of r and is randomly ordered. r[n .. r.length] will contain the elements not in r[0 .. n]. These will be in an undefined order, but will not be random in the sense that their order after partialShuffle returns will not be independent of their order before partialShuffle was called.

r must be a random-access range with length. n must be less than or equal to r.length. If no RNG is specified, rndGen will be used.

Parameters

rrandom-access range whose elements are to be shuffled
nnumber of elements of r to shuffle (counting from the beginning); must be less than r.length
gen(optional) random number generator to use; if not specified, defaults to rndGen

Returns

The shuffled random-access range.
fnRange partialShuffle(Range)(Range r, in size_t n) if (isRandomAccessRange!Range)

ditto