zig argsort example

argsort.zig

const std = @import("std");
const builtin = @import("builtin");

pub fn main() !void {
    const n = 20;
    var idx : [n]u8 = undefined;
    
    for (&idx, 0..) |*id, i| {
        id.* = @intCast(i);
    }
    
    var prng = std.rand.DefaultPrng.init(0);
    const rand = prng.random();
    
    var vals : [n]u8 = undefined;

    for (&vals) |*val| {
        val.* = rand.intRangeAtMost(u8, 0, 10);
    }
    
    const Thingy = struct {
        fn argcomp (context: []u8, a:u8, b:u8) bool {
            const one = context[a];
            const two = context[b];

            return one < two;
        }
    };
    
    const slice: []u8 = @as([]u8, &vals)[0..vals.len]; 
    std.mem.sort(u8, &idx, slice, Thingy.argcomp);
    
    std.debug.print("{any}\n", .{vals});
    for (idx) |i| {
        std.debug.print("{}\t -> {}\n", .{i, slice[i]});
    }
    
}