This page targets golang remove duplicates from slice, golang dedupe slice, golang unique slice, and remove duplicates from slice golang. It is not the same topic as golang remove from slice or delete element from slice golang at a known index—use golang remove from slice when you delete by position or filter while iterating without deduping the whole set.
Examples were run with a recent Go toolchain on Linux (stdlib only, including slices).
Preserve order: golang unique slice with a map
For golang get unique values from slice while keeping the first copy of each value, track seen and append once:
package main
import "fmt"
func uniquePreserveOrder[T comparable](in []T) []T {
seen := make(map[T]struct{})
out := make([]T, 0, len(in))
for _, v := range in {
if _, ok := seen[v]; !ok {
seen[v] = struct{}{}
out = append(out, v)
}
}
return out
}
func main() {
fmt.Println(uniquePreserveOrder([]int{8, 7, 5, 0, 0, 1, 2, 2, 8}))
}Run prints [8 7 5 0 1 2] with duplicates removed in first-seen order.
Sorted unique: sort then slices.Compact
When you only need golang slice remove duplicates and sorted output is acceptable, sort a copy then call slices.Compact:
package main
import (
"fmt"
"slices"
)
func main() {
a := []int{3, 1, 3, 2, 1, 2}
slices.Sort(a)
a = slices.Compact(a)
fmt.Println(a)
}Run prints [1 2 3]; original order is not preserved.
Count occurrences: map for golang remove duplicates diagnostics
package main
import "fmt"
func counts[T comparable](in []T) map[T]int {
m := make(map[T]int)
for _, v := range in {
m[v]++
}
return m
}
func main() {
in := []int{23, 8, 7, 5, 0, 0, 1, 2, 2, 8}
fmt.Println(counts(in))
}Run prints a map from each value to how many times it appeared; use that to decide which elements to drop or keep beyond simple dedupe.
XOR trick (narrow case only)
If every value except one appears an even number of times, XOR of all integers reveals the odd-one-out:
package main
import "fmt"
func xorSingleton(nums []int) int {
x := 0
for _, v := range nums {
x ^= v
}
return x
}
func main() {
nums := []int{8, 7, 5, 0, 0, 1, 2, 2, 8, 3, 4, 3, 4, 1, 6, 6, 7}
fmt.Println(xorSingleton(nums))
}Run prints 5. Do not use this for general golang array unique problems; it assumes the XOR property holds.
Summary
Golang remove duplicates from slice usually means either a map-backed pass that preserves first-seen order or a sort plus slices.Compact path when sorted golang unique slice output is fine. Maps also power golang get unique values from slice workflows that need counts before filtering. The XOR section is a small specialty case, not a replacement for map-based dedupe. For deleting a single index or golang remove element from slice while iterating without deduping the collection, use golang remove from slice.
