How to Sort a Map by Keys in Go - Step by Step Examples

How to Sort a Map by Keys in Go ?

Answer

To sort a map by keys in Go, you can extract the keys, sort them, and then iterate over the sorted keys to access the values. This method provides a way to display map entries in a sorted order.

✐ Examples

1 Sorting a Map by Keys Using a Slice of Keys

We can sort a map by keys in Go by extracting the keys into a slice, sorting the slice, and then iterating over the sorted keys to access the map values.

For example,

We start by importing the fmt and sort packages, which provide the necessary functions for input-output operations and sorting.
We declare and initialize a map named myMap with some key-value pairs. In this example, the map has integer keys and string values.
We extract the keys from the map and store them in a slice named keys.
We sort the slice of keys using the sort.Ints function.
We iterate over the sorted keys and print the key-value pairs in sorted order using the fmt.Println function.

Go Program

package main

import (
    "fmt"
    "sort"
)

func main() {
    // Declare and initialize a map
    myMap := map[int]string{
        3: "three",
        1: "one",
        2: "two",
    }

    // Extract the keys and store them in a slice
    keys := make([]int, 0, len(myMap))
    for key := range myMap {
        keys = append(keys, key)
    }

    // Sort the slice of keys
    sort.Ints(keys)

    // Iterate over the sorted keys and print the key-value pairs
    fmt.Println("Sorted Map by Keys:")
    for _, key := range keys {
        fmt.Printf("%d: %s\n", key, myMap[key])
    }
}

Output

Sorted Map by Keys:
1: one
2: two
3: three

2 Sorting a Map by Keys in Descending Order

We can sort a map by keys in descending order in Go by extracting the keys into a slice, sorting the slice in reverse order, and then iterating over the sorted keys to access the map values.

For example,

We start by importing the fmt and sort packages, which provide the necessary functions for input-output operations and sorting.
We declare and initialize a map named myMap with some key-value pairs. In this example, the map has integer keys and string values.
We extract the keys from the map and store them in a slice named keys.
We sort the slice of keys in reverse order using the sort.Sort function with a custom sort interface.
We iterate over the sorted keys and print the key-value pairs in sorted order using the fmt.Println function.

Go Program

package main

import (
    "fmt"
    "sort"
)

func main() {
    // Declare and initialize a map
    myMap := map[int]string{
        3: "three",
        1: "one",
        2: "two",
    }

    // Extract the keys and store them in a slice
    keys := make([]int, 0, len(myMap))
    for key := range myMap {
        keys = append(keys, key)
    }

    // Sort the slice of keys in descending order
    sort.Sort(sort.Reverse(sort.IntSlice(keys)))

    // Iterate over the sorted keys and print the key-value pairs
    fmt.Println("Sorted Map by Keys (Descending):")
    for _, key := range keys {
        fmt.Printf("%d: %s\n", key, myMap[key])
    }
}

Output

Sorted Map by Keys (Descending):
3: three
2: two
1: one

3 Sorting a Map by String Keys

We can sort a map by string keys in Go by extracting the keys into a slice, sorting the slice, and then iterating over the sorted keys to access the map values.

For example,

We start by importing the fmt and sort packages, which provide the necessary functions for input-output operations and sorting.
We declare and initialize a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We extract the keys from the map and store them in a slice named keys.
We sort the slice of keys using the sort.Strings function.
We iterate over the sorted keys and print the key-value pairs in sorted order using the fmt.Println function.

Go Program

package main

import (
    "fmt"
    "sort"
)

func main() {
    // Declare and initialize a map
    myMap := map[string]int{
        "three": 3,
        "one": 1,
        "two": 2,
    }

    // Extract the keys and store them in a slice
    keys := make([]string, 0, len(myMap))
    for key := range myMap {
        keys = append(keys, key)
    }

    // Sort the slice of keys
    sort.Strings(keys)

    // Iterate over the sorted keys and print the key-value pairs
    fmt.Println("Sorted Map by Keys:")
    for _, key := range keys {
        fmt.Printf("%s: %d\n", key, myMap[key])
    }
}

Output

Sorted Map by Keys:
one: 1
two: 2
three: 3

Summary

In this tutorial, we learned How to Sort a Map by Keys in Go language with well detailed examples.

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How to Sort a Map by Keys in Go - Step by Step Examples