Retrieve information from jsonObject

Can anyone help me with counting the number of passes and fails for each subject in a JSON object array? Here is an example:

 [{"Subject":"Maths","status:"Pass"},{"Subject":"Maths","status:"Pass"},
     {"Subject":"Maths","status:"Fail"},{"Subject":"Maths","status:"Fail"},
    {"Subject":"English","status:"Pass"},{"Subject":"English","status:"Fail"}]

I am looking to transform this data into an object array that looks like this:

[{"Subject":"Maths","Pass":2,"Fail":2},"Subject":"English","Pass":1,"Fail":1}]

This information will be coming from an API and the subjects may vary. Any suggestions on how to handle this dynamic data?

javascriptjson

Answer №1

In this code snippet, the reduce function is used along with an accumulator array to check if the 'Subject' exists. If it does not exist, a new object is created with the values of keys 'Subject', 'Pass', and 'Fail'. If the 'Subject' already exists, the values of 'Pass' and 'Fail' are updated accordingly.

let k = [{
    "Subject": "Maths",
    "status": "Pass"
  },
  {
    "Subject": "Maths",
    "status": "Pass"
  },
  {
    "Subject": "Maths",
    "status": "Fail"
  },
  {
    "Subject": "Maths",
    "status": "Fail"
  },
  {
    "Subject": "English",
    "status": "Fail"
  },
  {
    "Subject": "English",
    "status": "Pass"
  }
]

let res = k.reduce((acc, curr) => {
  let findSubjectIndex = acc.findIndex((item) => {
    return item.Subject === curr.Subject;
  })
  if (findSubjectIndex === -1) {
    let crtOb = Object.assign({}, {
      Subject: curr.Subject,
      Pass: curr.status === "Pass" ? 1 : 0,
      Fail: curr.status === "Fail" ? 1 : 0
    })
    acc.push(crtOb)

  } else {
    console.table(acc)
    acc[findSubjectIndex].Pass = acc[findSubjectIndex].Pass + (curr.status === "Pass" ? 1 : 0);
    acc[findSubjectIndex].Fail = acc[findSubjectIndex].Fail + (curr.status === "Fail" ? 1 : 0);
  }
  return acc;
}, []);
console.log(res)

Answer №2

Utilize Array.reduce and Object.values for efficient processing

let data = [{"Subject":"Maths","status":"Pass"},{"Subject":"Maths","status":"Pass"},
     {"Subject":"Maths","status":"Fail"},{"Subject":"Maths","status":"Fail"},
    {"Subject":"English","status":"Pass"},{"Subject":"English","status":"Fail"}];

// Generate an object with subject as key and values as desired objects
let processedData = Object.values(data.reduce((accumulator, {Subject, status}) => {
  // Check if subject exists in the object, update count accordingly
  if(accumulator[Subject]) accumulator[Subject][status] = (accumulator[Subject][status] || 0) + 1;
  // Add a new entry for the subject if it doesn't exist
  else accumulator[Subject] = {Subject, [status] : 1};
  return accumulator;
}, {}));
console.log(processedData);

Answer №3

Providing code that is more user-friendly and easy to grasp for beginners like myself

var jsonObject  = [{"Subject":"Maths","status":"Pass"},{"Subject":"Maths","status":"Pass"},
     {"Subject":"Maths","status":"Fail"},{"Subject":"Maths","status":"Fail"},
    {"Subject":"English","status":"Pass"},{"Subject":"English","status":"Fail"}];

var passMathCount = 0;
var failMathCount = 0;
var passEnglishCount= 0;
var failEnglishCount = 0;

//Loop through each object
for(var i = 0; i < jsonObject.length; i++) {
    
    var obj = jsonObject[i];
    //Determine status for different subjects
    if(obj.status == "Pass" && obj.Subject == "Maths")
      passMathCount++;
    else if(obj.status == "Fail" && obj.Subject == "Maths")
      failMathCount++;
    else if(obj.status == "Pass" && obj.Subject == "English")
      passEnglishCount++;
    else
      failEnglishCount++;
}

//Construct json object array
var jsonInstance = [{"Subject": "Maths", "pass": passMathCount, "fail":failMathCount},
                    {"Subject": "English", "pass": passEnglishCount, "fail":failEnglishCount}];
                    
console.log(jsonInstance);

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