I am trying to create a new array from existing array. Condition is that if element is duplicate then sum those elements. Please see below example for details as may be I am not able to explain clearly:
Input:
var arrayA = ["2", "1", "4", "2", "5", "1", "3", "2"];
Output:
var arrayB = ["6", "2", "4", "5", "3"];
here arrayB[0] = sum of 2s (2+2+2), arrayB[1] = sum of 1s (1+1)
I tried a lot but not able to figure out how I can achieve this.
Please help!
You can do it this way
arrayA = ["2", "1", "4", "2", "5", "1", "3", "2"];
//make a set
var set = new Set(arrayA);
var arrayB = [];
set.forEach(function(a) {
//for each set find in the original arrayA
var len = arrayA.filter(function(f) {
return f == a;
});
//push in arrayB set element * number of it occurance in original array
arrayB.push((+a) * (len.length));
})
console.log(arrayB)This should work:
var arrayA = ["2", "1", "4", "2", "5", "1", "3", "2"];
var tmp={};
for (var i=0; i<arrayA.length; i++)
tmp[arrayA[i]] = (tmp[arrayA[i]]||0)+1;
var res=[];
for (var i=0; i<arrayA.length; i++)
if(tmp[arrayA[i]]) {
res.push(arrayA[i]*tmp[arrayA[i]]);
delete tmp[arrayA[i]];
}
res would be:
[6, 2, 4, 5, 3]
You can do it by looping a first time to sum them up, and a second time to recreate the array:
var arrayA = ["2", "1", "4", "2", "5", "1", "3", "2"];
var arrayB = sumDuplicates(arrayA);
console.log(arrayB);
function sumDuplicates(arr) {
var obj = {}, res = [];
for(var i = 0, l = arr.length; i < l; i++)
obj[ arr[i] ] = (obj[ arr[i] ] || 0) + +arr[i]; // +arr[i] converts them to Numbers
// Now, obj = {"2": 6, "1": 2, "4": 4, "5": 5, "3": 3}
for(var i = 0, l = arr.length; i < l; i++)
if(arr.indexOf( arr[i] ) >= i) res.push( "" + obj[ arr[i] ] ); // Back to String
return res;
}var arrayA = ["2", "1", "4", "2", "5", "1", "3", "2"];
var arrayB = [];
for (var i = 0; i < arrayA.length; i++) {
if (arrayA.indexOf(arrayA[i]) === i) {
var count = 1;
for (var j = i + 1; j < arrayA.length; j++) {
if (arrayA[j] === arrayA[i]) {
count++;
}
}
arrayB.push(arrayA[i] * count);
}
}
console.log(arrayB);
// [ 6, 2, 4, 5, 3 ]
Solution using map given below:
var arrIn = ["2", "1", "4", "2", "5", "1", "3", "2"];
var arrOut = sumOfDupl(arrIn);
console.log(arrOut);
function sumOfDupl(arr) {
var mapKey = new Map();
var mapSum = {};
var resultArray = [];
for(var i = 0; i < arr.length; i++) {
mapSum[arr[i]] = (+ mapSum[arr[i]])?(+ mapSum[arr[i]] + (+ arr[i])): (+ arr[i]);
mapKey.set(arr[i], 1);
}
for (var [key, value] of mapKey) {
resultArray.push(mapSum[key]);
}
return resultArray;
}
arrayAwere sorted, this would be a much easier problem. So can you simply sort it as a first step? Also, doesarrayBhave to be in any particular order?