I'm storing some coordinates in an array. It looks like this:
const coords = [{x: 260, y: 60}, {x: 180, y: 0}, {x: 180, y: 240}, {x: 360, y: 120}, {x: 180, y: 60}, {x: 180, y: 60}, {x: 180, y: 60}]
How can I filter this array so the objects are unique, meaning there are no duplicates of objects with same x and y value? Expected output should be:
const coords = [{x: 260, y: 60}, {x: 180, y: 0}, {x: 180, y: 240}, {x: 360, y: 120}, {x: 180, y: 60}]
I've seen some similar solutions, but they didn't really solve this problem. I started with the following function
const output = Object.values(
coords.reduce( (c, e) => {
if (!c[e.x]) c[e.x] = e;
return c;
}, {})
but it only returns objects with different x values, so it just completely ommits y value.
One idea is to use a Set, map the x & y into a string, and then deserialize the Set to have unique x,y's..
eg..
const coords = [{x: 260, y: 60}, {x: 180, y: 0}, {x: 180, y: 240}, {x: 360, y: 120}, {x: 180, y: 60}, {x: 180, y: 60}, {x: 180, y: 60}];
const dedup = [...new Set(coords.map(m => `${m.x}:${m.y}`))].map(m => {
const [x,y] = m.split(':').map(n => n | 0);
return {x,y};
});
console.log(dedup);A pretty inefficient (O(n^2)), but flexible and straightforward solution: You first define a function that checks if two coordinates are equal. Then you filter all elements which have an equal element at a later position in the array.
const coords = [{x: 260, y: 60}, {x: 180, y: 0}, {x: 180, y: 240}, {x: 360, y: 120}, {x: 180, y: 60}, {x: 180, y: 60}, {x: 180, y: 60}]
const customUnique = (arr, isEqual) => {
// filter elements where an equal element exists at an earlier position
// thus the first element is kept
return arr.filter((a, i) => !arr.some((b, j) => i > j && isEqual(a, b)))
}
console.log(customUnique(coords, (a, b) => a.x === b.x && a.y === b.y))You can use originalArray.reduce() with an array instead of an object, so you can make use of array.find.
const coords = [{x: 260, y: 60}, {x: 180, y: 0}, {x: 180, y: 240}, {x: 360, y: 120}, {x: 180, y: 60}, {x: 180, y: 60}, {x: 180, y: 60}]
console.log(
coords.reduce((arr, e) => {
if (!arr.find(item => item.x == e.x && item.y == e.y)) {
arr.push(e);
}
return arr;
}, [])
);