import std.experimental.allocator;
import std.experimental.allocator.building_blocks.region;

InSituRegion!(1024) allocator;
auto aa = [1: 1.5, 3: 3.3, 2: 2.9];

auto s = (double[int] aa) @nogc @trusted pure nothrow {
    return allocator.makeSeries(aa);
}(aa);

auto indexArray = s.index.field;
auto dataArray = s.data.field;

assert(s.index == [1, 2, 3]);
assert(s.data == [1.5, 2.9, 3.3]);
assert(s.data[s.findIndex(2)] == 2.9);

allocator.dispose(indexArray);
allocator.dispose(dataArray);