Dynamically calculate the average for a nested collection using lodash

Question

I have a JSON array of objects (a collection) like:

[{
  \"x\": {
        \"x1\": 1
  },
  \"y\": {
    \"yt\": 0,
    \"zt\": 4,
    \"qa\": 3,
    \"ft\": 0,
          


        

Answer 1

let objectArray = [{
  "x": {
        "x1": 1
  },
  "y": {
    "yt": 0,
    "zt": 4,
    "qa": 3,
    "ft": 0,
  }
},
{
  "x": {
        "x1": 5
  },
  "y": {
    "yt": 10,
    "zt": 2,
    "qa": 0,
    "ft": 0,
  }
}];

function findAverage(array) {
  
  let counter = {},
    result = {},
    i,
    obj,
    key,
    subKey;
  
  // Iterate through array
  for (i = 0; i < array.length; i++) {
    obj = array[i];
    // Copy each key in array element to counter object
    for (key in obj) {
      counter[key] = counter[key] || {};
      // Increment and keep count of key-values of counter based on values in array element
      for (subKey in obj[key]) {
        counter[key][subKey] = counter[key][subKey] || {total: 0, numElements: 0};
        counter[key][subKey].total += obj[key][subKey];
        counter[key][subKey].numElements += 1;
      }
    }
  }
  // Go back through counter to find average of all existing subkeys (based on incremented total and the number of elements recorded) and throw it into result object
  for (key in counter) {
    result[key] = result[key] || {};
    
    for (subKey in counter[key]) {
      result[key][subKey] = counter[key][subKey].total / counter[key][subKey].numElements;
    }
  }
  
  return result;
}

console.log(findAverage(objectArray));

Not designed to be absolutely optimal, and copying objects can be done recursively without knowing in advance their structure, but I wanted to keep the steps as clear as possible.

Edited to allow testing as snippet. Had no idea you could even do that on SO!