CODEWITHSUNDEEP
javascriptarrays
shin1234
shin1234

Reputation: 217

Group and sum an array

I'm trying to dynamically retrieve, calculate and store some information in arrays.

Information that I have is:

var myArrayID = [];
    myArrayID = ['1', '2', '3', '4', '5', '1', '2', '3', '4', '5', '1', ........ '5']; 
   //100 ID in myArrayID that has been sorted in order 

var myArrayScore = [];
    myArrayScore = ['100', '70', '80', '88', '23', '99', ....... '20'];
  //100 Score in myArrayScore that has been sorted in order

In short

myArrayID[0] has reference to myArrayScore[0] ----> ID 1 has a score of 100

....

myArrayID[99] has a reference to myArrayScore[99] ----> ID 5 has a score of 20

I would like to get the total score of each individual ID without using my hardcode method

My method is

var ID1 = 1;
var ID2 = 2;
var ID3 = 3;
var ID4 = 4;
var ID5 = 5;

var ID1Score = 0;
var ID2Score = 0;
var ID3Score = 0;
var ID4Score = 0;
var ID5Score = 0;

for(var i in myArrayID)
{
     if(myArrayID[i] === ID1)
     {
         ID1Score += myArrayScore[i];
     }
     if(myArrayID[i] === ID2)
     {
         ID1Score += myArrayScore[i];
     }
     if(myArrayID[i] === ID3)
     {
         ID1Score += myArrayScore[i];
     }
     if(myArrayID[i] === ID4)
     {
         ID1Score += myArrayScore[i];
     }
     if(myArrayID[i] === ID5)
     {
         ID1Score += myArrayScore[i];
     }     
}

This method works but it is hard coded.

May I know if there's anyway to code it dynamically,

In a sense that, even if my array changes (assuming i have 9 ID instead) but it is still in a sorted order and it will still contain the same LENGTH.

Upvotes: 2

Views: 71

Answers (3)

Nina Scholz
Nina Scholz

Reputation: 386848

You can use an object for grouping the results and Array#forEach for the iterating.

At least you need a conversion to number.

var myArrayID = ['1', '2', '3', '4', '5', '1', '2', '3', '4', '5', '1', '5'],
    myArrayScore = ['100', '70', '80', '88', '23', '99', '20', '8', '9', '10', '11', '12'],
    score = {};

myArrayID.forEach(function (index) {
    score[index] = (score[index] || 0) + +myArrayScore[index] || 0;
});

document.write('<pre>' + JSON.stringify(score, 0, 4) + '</pre>');

Upvotes: 0

void
void

Reputation: 36703

var myArrayID = ['1', '2', '3', '4', '5', '1', '2', '3', '4', '5']; 
var myArrayScore = ['100', '70', '80', '88', '23', '100', '70', '80', '88', '23'];


var _f = {};

myArrayID.forEach(function(el, i){
  
  if(_f.hasOwnProperty(el)){
    _f[el] += +myArrayScore[i];
  }
  
  else{
   _f[el] = +myArrayScore[i]; 
  }
  
});

alert(JSON.stringify(_f));

// Score for first:
alert("1st Score: "+_f["1"]);

// Score for second:
alert("2nd Score: "+_f["2"]);

Upvotes: 1

gurvinder372
gurvinder372

Reputation: 68433

Try something like this

var outputMap = {};
myArray.forEach(function(val,index){
  outputMap[val] = outputMap[val] || 0;
  outputMap[val] += myArrayScore[index];
});

Now outputMap will have a value of total score against each individual ID.

DEMO

var myArrayID = ['1', '2', '3', '4', '5', '1', '2', '3', '4', '5']; 
var myArrayScore = ['100', '70', '80', '88', '23', '100', '70', '80', '88', '23'];

var outputMap = {};
myArrayID.forEach(function(val,index){
  outputMap[val] = outputMap[val] || 0;
  outputMap[val] += parseInt(myArrayScore[index],10);
});

document.body.innerHTML += JSON.stringify(outputMap,0,4);

Upvotes: 0

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