tg / gosortmap

Sort maps in Go

gosortmap

Sort maps in Go by keys or values. Works with most built-in types; own comparator can be provided to support custom types and ordering.

Example

m := map[string]int{"daikon": 2, "cabbage": 3, "banana": 1, "apple": 4}
for _, e := range sortmap.ByValue(m) {
	fmt.Printf("%s\t%d\n", e.Key, e.Value)
}
// Output:
// banana	1
// daikon	2
// cabbage	3
// apple	4

fmt.Println(sortmap.ByValueDesc(m).Top(2))
// Output:
// [{apple 4} {cabbage 3}]

Benchmark

This package favors convenience over the speed, so if the latter is preferable, you should go with an intermediate structure implementing sort.Interface and use sort.Sort directly. Here are the results for sorting map[int]int with 1000 values, indicating manual sorting can be up to 2x faster:

BenchmarkByKey-8           	     300	   4094204 ns/op
BenchmarkByKey_manual-8    	     500	   2367496 ns/op

BenchmarkByFunc-8          	     500	   3623426 ns/op
BenchmarkByFunc_manual-8   	    1000	   2122365 ns/op

(go 1.11.2, i7-6820HQ)