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Programming-Idioms

# 119 Deduplicate list
Remove duplicates from the list x.
Explain if the original order is preserved.
New implementation

Be concise.

Be useful.

All contributions dictatorially edited by webmasters to match personal tastes.

Please do not paste any copyright violating material.

Please try to avoid dependencies to third-party libraries and frameworks.

Other implementations 
(distinct x)
#include <algorithm>
#include <vector>
std::sort(x.begin(), x.end());
auto last = std::unique(x.begin(), x.end());
x.erase(last, x.end());
#include <string>
#include <unordered_set>
#include <vector>
std::vector<std::string> x = {"one", "two", "two", "one", "three"};
std::unordered_set<std::string> t;
for (auto e : x)
    t.insert(e);
using System.Collections.Generic;
using System.Linq;
var uniques = x.Distinct().ToList();
import std.container;
import std.array;
x = redBlackTree(x)[].array;
import std.algorithm;
import std.array;
x = x.sort.uniq.array;
x = x.toSet().toList();
Enum.uniq(x)
S = lists:usort(X)
func deduplicate[S ~[]T, T comparable](x S) S {
	seen := make(map[T]bool)
	j := 0
	for _, v := range x {
		if !seen[v] {
			x[j] = v
			j++
			seen[v] = true
		}
	}
	var zero T
	for i := j; i < len(x); i++ {
		// Avoid memory leak
		x[i] = zero
	}
	return x[:j]
}
import (
	"fmt"
	"slices"
)
slices.Sort(x)
x = slices.Compact(x)

y := make(map[T]struct{}, len(x))
for _, v := range x {
	y[v] = struct{}{}
}
x2 := make([]T, 0, len(y))
for _, v := range x {
	if _, ok := y[v]; ok {
		x2 = append(x2, v)
		delete(y, v)
	}
}
x = x2
seen := make(map[T]bool)
j := 0
for _, v := range x {
	if !seen[v] {
		x[j] = v
		j++
		seen[v] = true
	}
}
x = x[:j]
seen := make(map[T]bool)
j := 0
for _, v := range x {
	if !seen[v] {
		x[j] = v
		j++
		seen[v] = true
	}
}
for i := j; i < len(x); i++ {
	x[i] = nil
}
x = x[:j]
x.unique()
import Data.List (nub)
nub x
const seen = new Set();
x = x.filter( v => {
  if(seen.has(v))
    return false;
  seen.add(v);
  return true;
});
x = Array.from(new Set(x));
x = [...new Set(x)];
import java.util.ArrayList;
import java.util.LinkedHashSet;
x = new ArrayList<>(new LinkedHashSet<>(x));
import java.util.HashSet;
import java.util.Iterator;
final HashSet<T> seen = new HashSet<T>();
final Iterator<T> listIt = x.iterator();
while (listIt.hasNext()) {
  final T curr = listIt.next();
  if (seen.contains(curr)) {
    listIt.remove();
  } else {
    seen.add(curr);
  }
}
import java.util.Iterator;
import java.util.List;
Iterator<T> g;
T t;
int i, n;
for (i = 0, n = x.size(); i < n; ++i) {
    t = x.get(i);
    g = x.listIterator(i + 1);
    while (g.hasNext())
        if (g.next().equals(t)) {
            g.remove();
            --n;
        }
}
import java.util.HashSet;
import java.util.List;
import java.util.Set;
Set<T> uniques = new HashSet<>(x);
x.clear();
x.addAll(uniques);
import java.util.HashSet;
import java.util.ArrayList;
x = new ArrayList<T>(new HashSet<T>(x));
x = x.toSet().toList()
x = x.distinct()
(remove-duplicates x)
local seen = {}
for index,item in ipairs(x) do
	if seen[item] then
		table.remove(x, index)
	else
		seen[item] = true
	end
end
@import Foundation;
[NSSet setWithArray:x].allObjects
$x = array_unique($x);
uses classes;
var
  x: TList;
begin
  for i:= x.count-1 downto 0 do
    if x.indexOf(x.items[i]) <> -1 then
      x.delete(i);
end;
use List::MoreUtils 'uniq';
@x = uniq(@x);
def dedup(x):
  y = []
  for i in x:
    if not i in y:
      y.append(i)
  return y
from collections import OrderedDict
x = list(OrderedDict(zip(x, x)))
x = list(set(x))
x.uniq!
use itertools::Itertools;
let dedup: Vec<_> = x.iter().unique().collect();
x.sort();
x.dedup();
x = x.distinct
(define (remove-duplicates l)
  (cond ((null? l)
         '())
        ((member (car l) (cdr l))
         (remove-duplicates (cdr l)))
        (else
         (cons (car l) (remove-duplicates (cdr l))))))
(remove-duplicates x)
x asSet.
x intersection: x asSet.
x = x.Distinct.ToList

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