looping through Javascript Object returning sum of values

Question

What I'm trying to do is loop through an object getting the total times that each candidate appears and print that to the page.

I've have been racking my head on this one. I'm new to javascript and working with objects is something very new to me.

Thank you for the help!

var entry = [
  {
    candidate : "guy1",
    rank : 1,
    state : "AK",
    vote_count : "2"
  },
  {
    candidate : "guy2",
    rank : 1,
    state : "MI",
    vote_count : "3"
  },
  {
    candidate : "guy3",
    rank : 1,
    state : "AK",
    vote_count : "5"
  },
  {
    candidate : "guy2",
    rank : 1,
    state : "AL",
    vote_count : "4"
  },
  {
    candidate : "guy2",
    rank : 1,
    state : "FL",
    vote_count : "9"
  },
  {
    candidate : "guy1",
    rank : 1,
    state : "MN",
    vote_count : "7"
  }
];

for ( var i = 0, l = entry.canidate.length; i < l; i++ ) {
    guy1 += entry.canidate[i];
}

console.log(guy1);

To be clear, are you looking to get the number of times a candidate appears, or total up the number of votes for that candidate? — Rory McCrossan
– Rory McCrossan, Commented Jun 22, 2016 at 15:39
You have a type entry.canidate should be candidate. Also, entry.candidate is not a collection. entry is a collection. — Shaunak D
– Shaunak D, Commented Jun 22, 2016 at 15:41
Sorry. Yes, I'm looking to get the total times that each candidate appears. — anthonybetancourt
– anthonybetancourt, Commented Jun 22, 2016 at 15:44

Nina Scholz · Accepted Answer · 2016-06-22 16:18:41Z

3

You could use an object with the candidates as key and count the votes.

var entry = [{ candidate: "guy1", rank: 1, state: "AK", vote_count: "2" }, { candidate: "guy2", rank: 1, state: "MI", vote_count: "3" }, { candidate: "guy3", rank: 1, state: "AK", vote_count: "5" }, { candidate: "guy2", rank: 1, state: "AL", vote_count: "4" }, { candidate: "guy2", rank: 1, state: "FL", vote_count: "9" }, { candidate: "guy1", rank: 1, state: "MN", vote_count: "7" }],
    count = {};

entry.forEach(function (a) {
    count[a.candidate] = (count[a.candidate] || 0) + +a.vote_count;
});

console.log(count);

answered Jun 22, 2016 at 16:18

Nina Scholz

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2 Comments

Morteza Tourani Over a year ago

Why didn't use reduce like other answers?

Nina Scholz Over a year ago

because in this case reduce returns always the object count, which is not necessary.

Nicolas Bouvrette · Accepted Answer · 2016-06-22 15:48:49Z

You can create a new object with the summation of votes by candidates like this:

https://jsfiddle.net/he58xsb8/

var entry = [
  {
    candidate : "guy1",
    rank : 1,
    state : "AK",
    vote_count : "2"
  },
  {
    candidate : "guy2",
    rank : 1,
    state : "MI",
    vote_count : "3"
  },
  {
    candidate : "guy3",
    rank : 1,
    state : "AK",
    vote_count : "5"
  },
  {
    candidate : "guy2",
    rank : 1,
    state : "AL",
    vote_count : "4"
  },
  {
    candidate : "guy2",
    rank : 1,
    state : "FL",
    vote_count : "9"
  },
  {
    candidate : "guy1",
    rank : 1,
    state : "MN",
    vote_count : "7"
  }
];

var voteByCandidate = {};
for ( var i = 0; i < entry.length; i++ ) {
    var result = entry[i];
    if (!voteByCandidate[result.candidate]) {
        voteByCandidate[result.candidate] = 0;
    }
    voteByCandidate[result.candidate] += result.vote_count * 1; // Convert to number.
}

console.log(voteByCandidate);

Piyush.kapoor · Accepted Answer · 2016-06-22 15:48:03Z

0

You can create a candidateMap and loop entry array .for each same candidate increment the key in the map.

var candidateMap = {};

entry.forEach( function(candidate) {
   candidateMap[candidate.candidate] = candidateMap[candidate.candidate] || 0;
candidateMap[candidate.candidate] += 1;
});

answered Jun 22, 2016 at 15:48

Piyush.kapoor

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Comments

brk · Accepted Answer · 2016-06-22 16:48:06Z

0

I'm looking to get the total times that each candidate appears

You can use array filter to filter the candidates then reduce to count the number of occurrence of each candidate

var _filter=[];
entry.filter(function(item){
  _filter.push(item.candidate)
})

var _reducedArray =_filter.reduce(function(prev,next){
        prev[next] = (prev[next] + 1) || 1;
        return prev;
    },{});

console.log(_reducedArray);

JSFIDDLE

answered Jun 22, 2016 at 16:48

brk

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Comments

Morteza Tourani · Accepted Answer · 2016-06-22 17:01:09Z

0

You can easily do this with reduce:

var entries = [{ candidate: "guy1", rank: 1, state: "AK", vote_count: "2" }, { candidate: "guy2", rank: 1,  state: "MI", vote_count: "3" }, { candidate: "guy3", rank: 1, state: "AK", vote_count: "5" }, { candidate: "guy2", rank: 1, state: "AL", vote_count: "4" }, { candidate: "guy2", rank: 1, state: "FL", vote_count: "9" }, { candidate: "guy1", rank: 1, state: "MN", vote_count: "7" }];
var result = entries.reduce(function(r, c) {
  r[c.candidate] = (r[c.candidate] || 0) + parseInt(c.vote_count);
  return r;
}, {});
console.log(result);

edited Jun 22, 2016 at 17:01

answered Jun 22, 2016 at 16:19

Morteza Tourani

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Comments

Azamantes · Accepted Answer · 2016-06-22 17:08:59Z

0

This might be what you need:

const votes = {};
entry.foraEach(item => {
    if(!votes.hasOwnProperty(item.candidate)) {
        votes[item.candidate] = +item.vote_count;
    } else votes[item.candidate] += +item.vote_count;
});

You will have all the candidates and votes inside the votes object.

answered Jun 22, 2016 at 17:08

Azamantes

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Comments

ggSiMiDA · Accepted Answer · 2016-06-22 15:54:16Z

-1

var entry = [
  {
    candidate : "guy1",
    rank : 1,
    state : "AK",
    vote_count : "2"
  },
  {
    candidate : "guy2",
    rank : 1,
    state : "MI",
    vote_count : "3"
  },
  {
    candidate : "guy3",
    rank : 1,
    state : "AK",
    vote_count : "5"
  },
  {
    candidate : "guy2",
    rank : 1,
    state : "AL",
    vote_count : "4"
  },
  {
    candidate : "guy2",
    rank : 1,
    state : "FL",
    vote_count : "9"
  },
  {
    candidate : "guy1",
    rank : 1,
    state : "MN",
    vote_count : "7"
  }
];

function getCandidateTimes(entry, candidateName){
  var appearTimes = 0;
  for (var i=0, len = entry.length; i < len; i++){
    if(entry[i].candidate == candidateName){
      appearTimes++;
    }
  }
  return appearTimes;
}

var guy1AppearTimes = getCandidateTimes(entry, 'guy1');
console.log('guy1 appears ' + guy1AppearTimes + ' times!');

var guy2AppearTimes = getCandidateTimes(entry, 'guy2');
console.log('guy2 appears ' + guy2AppearTimes + ' times!');

//and so on.......

answered Jun 22, 2016 at 15:54

ggSiMiDA

1

2 Comments

techspider Over a year ago

you may consider adding some explanation over your answer.

ggSiMiDA Over a year ago

i am so sorry that to answer without any explanation, and it is my first time answer question in stackoverflow..

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