How to Compare if two Maps are Equal in Golang

Testing the equivalence of maps in Go
Created
Modified

reflect.DeepEqual Function

It first checks if both maps are nil, then it checks if they have the same length before finally checking to see if they have the same set of (key, value) pairs.

package main

import (
  "fmt"
  "reflect"
)

func main() {

  m1 := map[string]int{
    "a": 1,
    "b": 2,
  }

  m2 := map[string]int{
    "b": 2,
    "a": 1,
  }

  m3 := map[string]int{
    "b": 3,
    "c": 2,
  }

  fmt.Println(reflect.DeepEqual(m1, m2)) // true
  fmt.Println(reflect.DeepEqual(m1, m3)) // false

}
$ go run main.go
true
false

Comparison

To test whether two maps contain the same keys and the same associated values, we must write a loop:

package main

import (
  "fmt"
)

func main() {

  m1 := map[string]int{
    "a": 1,
    "b": 2,
  }

  m2 := map[string]int{
    "b": 2,
    "a": 1,
  }

  m3 := map[string]int{
    "b": 3,
    "c": 2,
  }

  fmt.Println(EqualMap(m1, m2)) // true
  fmt.Println(EqualMap(m1, m3)) // false

}

func EqualMap(x, y map[string]int) bool {
  if len(x) != len(y) {
    return false
  }
  for k, xv := range x {
    if yv, ok := y[k]; !ok || yv != xv {
      return false
    }
  }
  return true
}
$ go run main.go
true
false

Benchmark

After running the benchmark, we receive the following results:

func BenchmarkEqualMap(b *testing.B) {

  for i := 0; i < b.N; i++ {
    EqualMap(m1, m3) // false
    // reflect.DeepEqual(m1, m3)
  }

}
$ go test -bench=. --count=1
EqualMap     47.59 ns/op
DeepEqual   493.80 ns/op

Related Tags

#compare# #map#

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