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How to Remove Duplicate Values from Slice in Golang?
  • Last Updated : 10 May, 2020

An array is a data structure. Similarly, in Golang we have slice which is more flexible, powerful, lightweight and convenient than array. As slice is more flexible than array therefore, its flexibility is determined in terms of its size. Just like an array, it has indexing value and length but its size is not fixed. When we declare a slice we do not specify the size of it.

Syntax:

[]mySlice;
 OR
[]mySlice{};
OR
[]mySlice{input1, input2, .........input n}

Moreover, a slice and an array are connected with each other, in a slice, there is a referencing to an underlying array. And in a slice, we can store duplicate elements.

Example: Here, we will see how to remove the duplicate elements from slice. We have defined a function where we are passing the slice values and using the map function we are checking the duplicates and removing them.




// Golang program to remove duplicate
// values from Slice
package main
  
import (
    "fmt"
)
  
func removeDuplicateValues(intSlice []int) []int {
    keys := make(map[int]bool)
    list := []int{}
  
    // If the key(values of the slice) is not equal
    // to the already present value in new slice (list)
    // then we append it. else we jump on another element.
    for _, entry := range intSlice {
        if _, value := keys[entry]; !value {
            keys[entry] = true
            list = append(list, entry)
        }
    }
    return list
}
  
func main() {
  
    // Assigning values to the slice
    intSliceValues := []int{1,2,3,4,5,2,3,5,7,9,6,7}
  
    // Printing orignial value of slice
    fmt.Println(intSliceValues)
  
    // Calling function where we 
    // are removing the duplicates
    removeDuplicateValuesSlice := removeDuplicateValues(intSliceValues)
  
    // Printing the filtered slice
    // without duplicates
    fmt.Println(removeDuplicateValuesSlice)
}

Output:

[1 2 3 4 5 2 3 5 7 9 6 7]
[1 2 3 4 5 7 9 6]

Explanation:

  • From the main function, we have declared a slice. Also we have print the original value of the slice.
  • We have defined a function where we are passing the slice original values and checking the duplicates.
  • Logic for duplicate check : For this we have defined another slice and assigning the first values by checking if the value already exists in the new slice or not. It returns the slice without duplicates.
  • We are calling removeDuplicateValues function from main function where the return slice from the function is printed.

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