How to check if a map can match another partially in golang

Question

Suppose, I have two map[string]([]string)

 MAP1 := map[string]([]string) {
    "User" : []string{"11", "33"},
    "Type" : []string{"A"},
    }


MAP2 := map[string]([]string) {
    "User" : []string{"11", "17"},
    "Type" : []string{"B"},
    }

Here, MAP1 matches MAP2 partially.

User = 11 is in both map

How can I check this in a easy way?

Answer 1

For example:

package main

import "fmt"

func Max(x, y int) int {
    if x > y {
        return x
    }
    return y
}

func Intersect(as, bs []string) []string {
    i := make([]string, 0, Max(len(as), len(bs)))
    for _, a := range as {
        for _, b := range bs {
            if a == b {
                i = append(i, a)
            }
        }
    }
    return i
}

func main() {

    MAP1 := map[string][]string{
        "User": []string{"11", "33"},
        "Type": []string{"A"},
    }

    MAP2 := map[string][]string{
        "User": []string{"11", "17"},
        "Type": []string{"B"},
    }

    MAP3 := make(map[string][]string)

    for k, _ := range MAP1 {
        MAP3[k] = Intersect(MAP1[k], MAP2[k])
    }

    fmt.Println(MAP3) // MAP3 contains commonalities between MAP1 and MAP2
}

Note that this solution does not exploit any potential performance optimizations (like assuming that the string arrays will be sorted in some way, or else) and hence has a runtime performance of O(m • n²), where:

• m is the number of keys in the map (assumed to be the same for both maps)
• n is the number of elements in each string slice (assumed to be the same for both corresponding map entries)

Which is okay but not great.