im trying to add counting number for duplicate in JS. and i am completely stack in this case below. i need to compare objects with two value (x, y) and if there are same values of (x, y) add count 1 on new objects.
is there any way to convert data to newData such as below?
const data = [
{id: 1, x: 1, y: 1},
{id: 2, x: 2, y: 2},
{id: 3, x: 1, y: 1},
]
const newData = [
{x: 1, y:1 ,count:2}
{x: 2, y:2 ,count:1}
]
use .reduce() function
const data = [
{id: 1, x: 1, y: 1},
{id: 2, x: 2, y: 2},
{id: 3, x: 1, y: 1},
]
const output = data.reduce((acc, curr) => {
curr.count = 1;
const exists = acc.find(o => o.x === curr.x && o.y === curr.y);
exists ? exists.count++ : acc.push(({ x, y, count } = curr));
return acc;
}, []);
console.log(output);.as-console-wrapper { max-height: 100% !important; top: 0; }
One way of doing so, is to create a map with the x and y values, and increment the count accordingly, then convert the map into an array:
const data = [
{id: 1, x: 1, y: 1},
{id: 2, x: 2, y: 2},
{id: 3, x: 1, y: 1},
]
const makeXYMap = (data) => data.reduce((acc, cur) => {
const { x, y } = cur;
const entry = acc[`${x}_${y}`];
if (entry) {
acc[`${x}_${y}`] = {...entry, count: entry.count + 1};
} else {
acc[`${x}_${y}`] = { x, y, count: 1 };
}
return acc;
}, {});
const makeArray = (XYMap) => Object.values(XYMap);
console.log(makeArray(makeXYMap(data)));Note that complexity wise, this solution is a O(N).
const data = [
{ id: 1, x: 1, y: 1 },
{ id: 2, x: 2, y: 2 },
{ id: 3, x: 1, y: 1 },
// .. so on ..
];
const countedData = data.reduce((acc, { x, y }, index, array) => {
acc[`x${x}y${y}`] = {
x,
y,
count: (acc[`x${x}y${y}`] ? acc[`x${x}y${y}`].count : 0) + 1
};
return index === (array.length - 1) ? Object.values(acc) : acc;
}, {});
console.log(countedData);Use forEach and build an object with key (made of x, y) and values (aggregate count). Get the Object.values to get the results as array.
const data = [
{id: 1, x: 1, y: 1},
{id: 2, x: 2, y: 2},
{id: 3, x: 1, y: 1},
]
const counts = (arr, res = {}) => {
arr.forEach(({x , y}) =>
res[`${x}-${y}`] = { x, y, count: (res[`${x}-${y}`]?.count ?? 0) + 1 })
return Object.values(res);
}
console.log(counts(data))