count all values on object array - javascript

Question

I need to count each value on the object array , the desired output should be like below

[{
    "question": "question1",
    "USA": 2
  }, {
    "question": "question1",
    "AUS": 1
  },

  {
    "question": "question2",
    "item1": 2
  },

  {
    "question": "question2",
    "item1,item2": 1
  }, {
    "question": "question4",
    "3": 1
  }, {
    "question": "question4",
    "2": 1
  }
]

Below is the input I need to transform in to the above output. I have no clue how to do with n no of question and also got issue when one question has 2 answers . sample input

[{"question1":"USA","question2":["item1"],"question4":2}, 
{"question1":"USA","question2":["item1"],"question4":3}, 
{"question1":"AUS","question2":["item1","item2"]}];

let arr=[{"question1":"USA","question2":["item1"],"question4":2},{"question1":"USA","question2":["item1"],"question4":3},{"question1":"AUS","question2":["item1","item2"]}];
//console.log(arr);



function solve(list){
    var map = new Map();
    var entry = null;
    for(var item of list){
        if(!map.has(item.question1))
            map.set(item.question1, {question:'question1'});

            entry = map.get(item.question1);

        if(entry.hasOwnProperty(item.question1))
            entry[item.question1] = entry[item.question1] + 1;
        else
            entry[item.question1] = 1;
            
         
          if(!map.has(item.question2))
            map.set(item.question2, {question: 'question2'});

            entry = map.get(item.question2);

        if(entry.hasOwnProperty(item.question2))
            entry[item.question2] = entry[item.question2] + 1;
        else
            entry[item.question2] = 1;
         
    }
    return Array.from(map.values());
}
console.log(solve(arr))

^^ JSON is a textual notation for data exchange. (More here.) If you're dealing with JavaScript source code, and not dealing with a string, you're not dealing with JSON. — T.J. Crowder
– T.J. Crowder, Commented Mar 21, 2019 at 7:04

Nina Scholz · Accepted Answer · 2019-03-21 07:54:39Z

You could take an object or what ever data structure you like which supports a key/value structure in a nested style and collect first all items and then reder the collected tree.

This approach uses objects, because the keys are strings, this is important for an array as key. This is joint with a comma which is sufficient for this use case.

var data = [{ question1: "USA", question2: ["item1"], question4: 2 }, { question1: "USA", question2: ["item1"], question4: 3 }, { question1: "AUS", question2: ["item1", "item2"] }],
    hash = data.reduce((hash, o) => {
        Object.entries(o).forEach(([question, value]) => {
            var sub = hash[question] = hash[question] || Object.create(null);
            sub[value] = sub[value] || { question, [value]: 0 };
            sub[value][value]++;
        });
        return hash;
    }, Object.create(null)),
    result = Object.values(hash).reduce((r, sub) => [...r, ...Object.values(sub)], []);

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Jack Bashford · Accepted Answer · 2019-03-21 07:20:25Z

1

First, obtain the countries by using reduce. Then use some nested forEach loops for the rest:

const input = [{"question1":"USA","question2":["item1"],"question4":2}, 
{"question1":"USA","question2":["item1"],"question4":3}, 
{"question1":"AUS","question2":["item1","item2"]}];
const countriesOutput = input.reduce((acc, curr) => {
  if (!acc.some(e => e[curr.question1])) {
    acc.push({ question: "question1", [curr.question1]: 1 });
  } else {
    acc.find(e => e[curr.question1])[curr.question1]++;
  }
  return acc;
}, []);
let questionsOutput = [];
input.forEach(item => {
  Object.keys(item).forEach(key => {
    if (key != "question1") {
      if (Array.isArray(item[key])) {
        questionsOutput.push({ question: key, [item[key].join(",")]: 1 });
      } else {
        questionsOutput.push({ question: key, [item[key]]: 1 });
      }
    }
  });
});
const finalOutput = [...countriesOutput, ...questionsOutput];
console.log(finalOutput);

.as-console-wrapper { max-height: 100% !important; top: auto; }

answered Mar 21, 2019 at 7:20

Jack Bashford

44.3k11 gold badges56 silver badges84 bronze badges

1 Comment

sumit Over a year ago

Thanks for the answer, "item1" count should be 2, I was also stucked there

Charlie · Accepted Answer · 2019-03-21 09:01:27Z

Its a matter of summarizing the input using a dictionary (like Object) and track the duplicates. The "name" of the name/value pair can be uniquely identified by combining the question and answer with some delimiter.

const input = [{
    "question1": "USA",
    "question2": ["item1"],
    "question4": 2
  },
  {
    "question1": "USA",
    "question2": ["item1"],
    "question4": 3
  },
  {
    "question1": "AUS",
    "question2": ["item1", "item2"]
  }
];



//Sum the input to an array which we can easily search for duplciates
var repeatCounter = {};

input.forEach(objItem => {

  Object.keys(objItem).forEach(propItem => {


    //Get the counter and the string
    var s = `${propItem}-${objItem[propItem]}`;
    var c = repeatCounter[s] || 0;

    //Modify it or introduce it if absent
    repeatCounter[s] = c + 1;


  })

})




var output = Object.keys(repeatCounter).map(element => {

  var ret = {'question': element.split('-')[0]}

  ret[element.split('-')[1]] = repeatCounter[element];
  
  return ret;

})


   console.log(output);

.as-console-wrapper {
  max-height: 100% !important;
}

Subtle adjustments such as fortifying the delimiter, converting multiple strings in to array items(as shown in the question) needs to be done on practical grounds.

Collectives™ on Stack Overflow

count all values on object array - javascript

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related