How to Sort a Map by Value in Go

1. Introduction

Sorting a map by its values is a task that can be necessary when you need to order elements by criteria other than their keys. Go does not inherently support sorting maps by values directly. However, with a few more steps, it can be accomplished using thesort package and a custom sort logic. This blog post will guide you through sorting a map by values in Go.

2. Program Steps

1. Create and populate a map.

2. Extract key-value pairs into a slice of structs.

3. Sort the slice of structs based on the values.

4. Print out the sorted key-value pairs from the slice.

3. Code Program

Sorting a map by value in Go involves creating a separate data structure to hold the map's key-value pairs, and then sorting that structure according to the values. This often requires the creation of a slice of value-key pairs or struct elements to apply custom sorting logic.

Here is the complete Go program to demonstrate how to sort a Map by values:
package mainimport ("fmt""sort")// KeyValue holds a single key-value pair.type KeyValue struct {Key   stringValue int}func main() {// Step 1: Create and populate a map.rankings := map[string]int{"Alice": 2,"Bob":   1,"Claire": 3,}// Step 2: Extract key-value pairs into a slice of KeyValue.kvSlice := make([]KeyValue, 0, len(rankings))for k, v := range rankings {kvSlice = append(kvSlice, KeyValue{k, v})}// Step 3: Sort the slice based on the values.sort.Slice(kvSlice, func(i, j int) bool {return kvSlice[i].Value < kvSlice[j].Value})// Step 4: Print out the sorted key-value pairs.fmt.Println("Rankings sorted by score:")for _, kv := range kvSlice {fmt.Printf("%s has a score of %d\n", kv.Key, kv.Value)}}

Output:

Rankings sorted by score:Bob has a score of 1Alice has a score of 2Claire has a score of 3

Explanation:

1.package main - The package declaration for the Go program.

2.import "fmt" andimport "sort" - Import statements for the Format package and the Sort package.

3.rankings - A map that stores names as keys and scores as values is declared and initialized.

4.KeyValue - A struct type to hold a single key-value pair from the map is defined.

5.kvSlice - A slice ofKeyValue structs is created to store the map's key-value pairs.

6. Afor loop populateskvSlice with the map's content.

7.sort.Slice is used to sortkvSlice by theValue field ofKeyValue structs, defining an anonymous function for the less logic.

8. Anotherfor loop iterates over the sortedkvSlice to print the ranking.

9. The output displays the sorted rankings according to the scores.


Related Go (Golang) Source Code Examples:

Go Tutorial - Hello World AppGo function simple exampleGo function multiple return valuesGo anonymous functionGo variadic functionGo recursive functionGo defer function callGo pass parameters by valueGo function as a parameterGo custom function typesGo filter slice exampleGo closure function exampleGo higher-order functionGo Example: ConstantsGo Example: VariablesGo Example: ArraysGo Example: SlicesGo Example: MapsGo Example: RangeGo Example: PointersGo Example: ValuesGo Example: Base64 EncodingGo Example: Time Formatting / ParsingGo Variable ExamplesGo Example: InterfaceGo - Operator ExamplesGo - Arithmetic OperatorsGo - Boolean OperatorsGo - Comparison OperatorsGo - Bitwise OperatorsGo - Read Input From User With ScanfGo - Read Input From User With NewReaderGo - Read Input From User With NewScannerHow to Get Input From User in GolangGo - for Loop ExampleGo - If/Else ExampleGo - Switch/Case Statement ExampleHow to Concatenate Strings in GoHow to Convert String to Int in GolangHow to Convert String to Array in GolangHow to Convert String to Int64 in GolangHow to Convert Int to String in GolangGo - Array ExampleGo - Array Iteration ExampleGo - Multidimensional Array ExampleHow to Iterate Over Arrays in Go Using RangeHow to Pass Arrays to Functions in GoHow to Copy and Clone Arrays in GoHow to Convert Array to Slice in GolangHow to Sort Array in GolangHow to Implement Custom Sort on Arrays in GoHow to Open and Close Files in GoHow to Read from a File in GoHow to Write to a File in GoHow to Check if a File Exists in GoHow to Delete a File in GoHow to Copy a File in GoHow to Move or Rename a File in GoHow to Change File Permissions in GoHow to Create a Directory in GoHow to List Files in a Directory in GoHow to Recursively Traverse Directories in GoGo - read file into stringGo - read file line by lineGo - write to file with File.WriteStringGo - write to file with ioutil.WriteFileHow to read and write a file in GoLangGo - create directory exampleHow to check if a directory exists in GolangGo - create, rename and delete directory examplesGo - Create Slice ExampleGo - Slice Length and Capacity ExampleGo - Slice Iteration ExampleGo - Slice Append ExampleGo - Slice Copy ExampleGo - Slice Remove Element ExampleGo - Slice Sorting ExampleHow to Delete Elements from a Slice in GoHow to Sort Slice in GolangGo - Multidimensional Slices ExampleHow to Convert an Array to a Slice in GoHow to Reverse a Slice in GoHow to Concatenate Multiple Slices in GoHow to Check if Slice Is Empty GolangGo - Custom Slice Types ExampleHow to Declare and Initialize a Map in GoHow to Add or Update Elements in a Map in GoHow to Retrieve Values from a Map in GoHow to Check if Key Exists in Map GolangHow to Iterate Over a Map in GoHow to Sort a Map by Key in GoHow to Sort a Map by Value in GoHow to Pass a Map to a Function in GoHow to Copy a Map in GoHow to Create Nested Maps in GoHow to Compare Maps in GoHow to Convert a Map into a Slice in GoGo - Map ExampleGo - Map loop exampleGo - Map check if value existsGo - Map remove element exampleGo Structs ExampleGo - anonymous struct exampleGo - nested structs exampleGo - struct functions fields exampleGo - struct constructor exampleGolang - MySQL Delete ExampleGolang - MySQL Update ExampleGolang - MySQL Select ExampleGolang - MySQL Insert ExampleHow to Convert String to JSON in GolangHow to Convert Struct to JSON in GolangHow to Convert Map to JSON in GolangHow to Convert JSON to Map in GolangHow to Convert XML to JSON in GolangGolang Interpolation Search AlgorithmGolang Recursion AlgorithmGolang Binary Search AlgorithmGolang Linear Search AlgorithmGolang Quick Sort AlgorithmGolang Merge Sort AlgorithmGolang Shell Sort AlgorithmGolang Insertion Sort AlgorithmGolang Selection Sort AlgorithmGolang AVL Tree with ExampleGolang Binary Search Tree with ExampleDesign Patterns in Go (Golang)Data Structures and Algorithms in Go

Comments

Post a Comment