Go Slice with Unique Values

In Go, slices can contain duplicate elements, but sometimes you need a slice with only unique values. Achieving this requires filtering the slice to remove duplicates. Go does not provide a built-in function for this, but you can implement it using maps for efficient duplicate removal.

In this tutorial, we will explore how to create a slice with unique values in Go using practical examples and detailed explanations.

Steps to Create a Slice with Unique Values

Use a Map: Create a map to track elements that have already been added to the result slice.
Iterate Through the Slice: Check each element against the map to determine if it is a duplicate.
Append Unique Elements: Add elements to the result slice only if they are not already in the map.

Examples of Creating a Slice with Unique Values

1. Remove Duplicates from a Slice of Integers

This example demonstrates how to remove duplicates from a slice of integers:

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package main

import "fmt"

// Function to create a slice with unique values
func uniqueSlice(slice []int) []int {
    uniqueMap := make(map[int]bool)
    result := []int{}

    for _, v := range slice {
        if !uniqueMap[v] {
            uniqueMap[v] = true
            result = append(result, v)
        }
    }

    return result
}

func main() {
    // Declare and initialize a slice with duplicate values
    numbers := []int{10, 20, 30, 20, 40, 10, 50}

    // Create a slice with unique values
    uniqueNumbers := uniqueSlice(numbers)

    // Print the result
    fmt.Println("Original Slice:", numbers)
    fmt.Println("Unique Slice:", uniqueNumbers)
}

Explanation

Initialize Map: A map is created to track elements that have already been added to the result slice.
Iterate Through Slice: Each element of the slice is checked against the map.
Filter Duplicates: If an element is not present in the map, it is added to the result slice and marked as seen in the map.
Return Result: The result slice containing only unique elements is returned.

Output

2. Remove Duplicates from a Slice of Strings

This example demonstrates how to remove duplicates from a slice of strings:

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package main

import "fmt"

// Function to create a slice with unique values
func uniqueSlice(slice []string) []string {
    uniqueMap := make(map[string]bool)
    result := []string{}

    for _, v := range slice {
        if !uniqueMap[v] {
            uniqueMap[v] = true
            result = append(result, v)
        }
    }

    return result
}

func main() {
    // Declare and initialize a slice with duplicate values
    words := []string{"apple", "banana", "cherry", "apple", "date", "banana"}

    // Create a slice with unique values
    uniqueWords := uniqueSlice(words)

    // Print the result
    fmt.Println("Original Slice:", words)
    fmt.Println("Unique Slice:", uniqueWords)
}

Explanation

Initialize Map: A map is created to track elements that have already been added to the result slice.
Iterate Through Slice: Each element of the slice is checked against the map.
Filter Duplicates: If an element is not present in the map, it is added to the result slice and marked as seen in the map.
Return Result: The result slice containing only unique elements is returned.

Output

Points to Remember

Efficient Deduplication: Using a map ensures efficient removal of duplicates with a time complexity of O(n), where n is the length of the slice.
Preserve Order: The order of elements in the result slice matches their order of first occurrence in the original slice.
Generic Logic: The same approach can be applied to slices of other types, such as integers, strings, or custom structs.
Memory Consideration: Using a map requires additional memory proportional to the number of unique elements in the slice.

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Go Slice with Unique Values