What is the most efficient method for reducing this array?
data = {
id: [1, 1, 1, 3, 3, 4, 5, 5, 5, ...]
v: [10,10,10, 5, 10 ...]
}
Each id has a corresponding value in v. The goal is to sum up the values of v for each id. Based on the example provided, the desired result would be:
data = {
id: [1, 3, 4, 5, ...]
v: [30, 15, ...]
}
My recommendation would be to utilize the Array.prototype.reduce() method as it offers a simple and elegant solution.
var ids = [1, 1, 1, 3, 3, 3, 3, 4, 5, 6, 6, 6],
v = [10, 10, 10, 5, 10, 10, 10, 404, 505, 600, 60, 6],
data = {};
data.v = [];
data.ids = ids.reduce(function(a, b, index) {
if (a.indexOf(b) < 0) a.push(b);
if (!data.v[a.indexOf(b)]) data.v[a.indexOf(b)] = 0;
data.v[a.indexOf(b)] += v[index];
return a;
}, []);
To achieve this with two arrays of the same length, you can utilize mapping and reducing:
const ids = [1, 1, 1, 3, 3];
const vs = [10,10,10,5,10];
const reduced = ids
.map((val, i) => ({ id: val, value: vs[i] }))
.reduce((agg, next) => {
agg[next.id] = (agg[next.id] || 0) + next.value;
return agg;
}, {});
console.log(reduced);
// Object {1: 30, 3: 15}
Here's a live demonstration: https://jsfiddle.net/h1o5rker/1/
I believe this task can be achieved using the reduce method.
var data = {
id: [1, 1, 1, 3, 3],
v: [10, 10, 10, 5, 10]
}
var sumsObjs = data.v.reduce(function(sum, val, index) {
var id = data.id[index];
if (sum[id] !== undefined) {
sum[id] = sum[id] + val;
} else {
sum[id] = val;
}
return sum;
}, {});
console.log(sumsObjs);<script src="https://getfirebug.com/firebug-lite-debug.js"></script>let data = {
id: [1, 1, 1, 10, 123, 4531],
v: [123, 123, 53, 223, 11, 11, 11]
};
let _v = data.v;
let vinit;
document.write(data.v + '<br>');
for (let i = 0; i < _v.length; i++) {
vinit = _v[i];
for (let j = i + 1; j <= _v.length; j++) {
if (_v[j] === vinit) {
delete _v[j];
}
}
}
document.write(data.v);
let data = {
id: [1, 1, 1, 10, 123, 4531],
v: [123, 123, 53, 223, 11, 11, 11,...]
};
let _v = data.v;
let vinit;
for (let i = 0; i < _v.length; i++) {
vinit = _v[i];
for (let j = i + 1; j <= _v.length; j++) {
if (_v[j] === vinit) {
delete _v[j];
}
}
}
The provided code snippet focuses on reducing repeating elements in array 'v', but similar implementation can be done for array 'id' as well by introducing additional variables.
In the code snippet, the presence of extra commas in the second line indicates the deletion of those specific elements.
If the IDs appear in consecutive order, a simple for loop can effectively handle the task without unnecessary complexity.
data = {
id: [1, 1, 1, 3, 3, 4, 5, 5, 5],
v: [10, 10, 10, 5, 10, 1, 2, 3, 4]
};
var result = {
id: [],
v: []
};
(function() {
var ids = data.id,
vals = data.v,
lastId = ids[0],
runningTotal = vals[0];
for (var i = 1; i < ids.length; i++) {
if (lastId === ids[i]) {
runningTotal += vals[i];
}
if (lastId !== ids[i] || i + 1 === ids.length) {
result.id.push(lastId);
result.v.push(runningTotal);
lastId = ids[i];
runningTotal = vals[i];
}
}
}());
console.log(result);Several solutions have been shared by different individuals, but none seem to precisely match your requirements. I would like to offer a solution that specifically caters to your needs and simplifies the object while maintaining its original format.
// Your current data object
data = {
id: [1, 1, 1, 3, 3],
v: [10,10,10, 5, 10]
}
// Function to reduce the object based on 'id' and 'v'
function simplify(obj){
// Initializing the reduced object structure
var simplifiedObj = {
id: [],
v: []
}
// Creating a hash map to store keys and values
var map = {};
for(var i=0; i<obj.id.length; ++i){
// Check if key exists in the map, if not create it with value 0
if(typeof map[parseInt(obj.id[i])] === 'undefined'){
map[parseInt(obj.id[i])] = 0;
}
// Summing values for each key
map[parseInt(obj.id[i])] += parseInt(obj.v[i]);
}
// Mapping the hash map back to the reduced object
for(var ele in map){
simplifiedObj.id.push(ele);
simplifiedObj.v.push(map[ele]);
}
// Return the simplified object
return simplifiedObj;
}
var mySimplifiedObject = simplify(data);
console.log(mySimplifiedObject);
This code provides a solution for organizing IDs using Array.prototype.reduce().
var data = {
id: [1, 1, 1, 3, 3, 4, 5, 5, 5],
v: [10, 10, 10, 5, 10, 7, 8, 10, 13]
},
result = { id: [], v: [] };
data.id.reduce(function (r, a, i) {
if (r === a) {
result.v[result.v.length - 1] += data.v[i];
} else {
result.id.push(a);
result.v.push(data.v[i]);
}
return a;
}, -1);
document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');Alternatively, there is an in-place version of the solution.
var data = {
id: [1, 1, 1, 3, 3, 4, 5, 5, 5],
v: [10, 10, 10, 5, 10, 7, 8, 10, 13]
};
void function (d) {
var i = 1;
while (i < d.id.length) {
if (d.id[i - 1] === d.id[i]) {
d.id.splice(i, 1);
d.v[i - 1] += d.v.splice(i, 1)[0];
continue;
}
i++;
}
}(data);
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