Combinations

Lazy Forward range of Combinations. It always generates combinations from 0 to n - 1, use indexedRoR to map it to your range.

Generating a new combination is in O(k), the number of combinations is binomial(n, k).

struct Combinations (

T

) if (

isUnsigned!T &&

T.sizeof <= size_t.sizeof

) {

import mir.ndslice.slice : Slice;;

alias DeepElement = T;

this(size_t n, T[] state);

Slice!(const(T)*) front [@property getter];

void popFront();

size_t length [@property getter];

bool empty [@property getter];

size_t[2] shape [@property getter];

Combinations save [@property getter];

}

Constructors

this this(size_t n, T[] state): state should have the length of repeat

Members

Aliases

DeepElement alias DeepElement = T

Functions

popFront void popFront()
empty bool empty [@property getter]: Input range primitives

Properties

front Slice!(const(T)*) front [@property getter]
length size_t length [@property getter]: Input range primitives
save Combinations save [@property getter]: Forward range primitive. Allocates using GC.
shape size_t[2] shape [@property getter]

Examples

import mir.ndslice.fuse;
import mir.ndslice.topology: iota;
assert(iota(3).combinations(2).fuse == [[0, 1], [0, 2], [1, 2]]);
assert("AB"d.combinations(2).fuse == ["AB"d]);
assert("ABC"d.combinations(2).fuse == ["AB"d, "AC"d, "BC"d]);

import mir.algorithm.iteration: equal;
import mir.ndslice.slice: sliced;
import mir.ndslice.topology: iota;

import std.experimental.allocator.mallocator;
auto alloc = Mallocator.instance;

static immutable expected3r2 = [
    0, 1,
    0, 2,
    1, 2];
auto r = iota(3);
auto rc = alloc.makeCombinations(r.length, 2);
assert(expected3r2.sliced(3, 2).equal(rc.indexedRoR(r)));
alloc.dispose(rc);

See Also

combinations, makeCombinations

Meta

Source

See Implementation

mir combinatorics functions

structs