JavaScript: A guide to calculating the average of a JSON array using certain criteria within the keys/fields

Question

JavaScript: A guide to calculating the average of a JSON array using certain criteria within the keys/fields

I have a scenario where I need to calculate the average values of specific keys in an array:

const users = [
  { name: 'Adam', age: 20, country: 'France', weight: 100 },
  { name: 'Adam', age: 28, country: 'Germany', weight: 100 },
  { name: 'Adam', age: 28, country: 'India', weight: 200 },
  { name: 'Adam', age: 40, country: 'France', weight: 200 },
  { name: 'Oliver', age: 28, country: 'France', weight: 200 }
];

The averaging should be done based on the keys 'name' and 'country' for the keys 'age' and 'weight'

output = [
  { name: 'Adam', age: 30, country: 'France', weight: 150 },
  { name: 'Adam', age: 28, country: 'Germany', weight: 100 },
  { name: 'Adam', age: 28, country: 'India', weight: 200 },
  { name: 'Oliver', age: 28, country: 'France', weight: 200 }
];

If certain keys are not defined, they should be removed during the calculation process:

In this case, averaging is based solely on the key 'name' for 'age' and 'weight'

output = [
  { name: 'Adam', age: 29, weight: 150 },
  { name: 'Oliver', age: 28, weight: 200 }
];

javascript arrays json average reduce

Answer 1

Answer №1

To streamline the data, you can categorize it based on specific keys and calculate the average values for each key within a group.

function getAverages(array, groupKeys, averageKeys) {
    var groups = {},
        result = [];

    array.forEach(o => {
        var key = groupKeys.map(k => o[k]).join('|'),
            group = groups[key];

        if (!group) {
            groups[key] = { count: 0, payload: {} };
            group = groups[key];
            averageKeys.forEach(k => group[k] = 0);
            groupKeys.forEach(k => group.payload[k] = o[k]);
            result.push(group.payload);
        }
        groups[key].count++;
        averageKeys.forEach(k => group.payload[k] = (group[k] += o[k]) / group.count);
    })
    return result;
}

const users = [{ name: 'Adam', age: 20, country: 'France', weight: 100 }, { name: 'Adam', age: 28, country: 'Germany', weight: 100 }, { name: 'Adam', age: 28, country: 'India', weight: 200 }, { name: 'Adam', age: 40, country: 'France', weight: 200 }, { name: 'Oliver', age: 28, country: 'France', weight: 200 }];

console.log(getAverages(users, ['name', 'country'], ['age', 'weight']));
console.log(getAverages(users, ['name'], ['age', 'weight']));

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

Answer 2

To streamline the data, you can categorize it based on specific keys and calculate the average values for each key within a group.

function getAverages(array, groupKeys, averageKeys) {
    var groups = {},
        result = [];

    array.forEach(o => {
        var key = groupKeys.map(k => o[k]).join('|'),
            group = groups[key];

        if (!group) {
            groups[key] = { count: 0, payload: {} };
            group = groups[key];
            averageKeys.forEach(k => group[k] = 0);
            groupKeys.forEach(k => group.payload[k] = o[k]);
            result.push(group.payload);
        }
        groups[key].count++;
        averageKeys.forEach(k => group.payload[k] = (group[k] += o[k]) / group.count);
    })
    return result;
}

const users = [{ name: 'Adam', age: 20, country: 'France', weight: 100 }, { name: 'Adam', age: 28, country: 'Germany', weight: 100 }, { name: 'Adam', age: 28, country: 'India', weight: 200 }, { name: 'Adam', age: 40, country: 'France', weight: 200 }, { name: 'Oliver', age: 28, country: 'France', weight: 200 }];

console.log(getAverages(users, ['name', 'country'], ['age', 'weight']));
console.log(getAverages(users, ['name'], ['age', 'weight']));

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

Answer 3

Answer №2

If you want to achieve specific objectives, you can utilize functions such as filter, map, and reduce.

For ensuring the existence of keys, you can filter out entries that do not contain those keys:

// Filter out entries without the age property
const validUsers = users.filter(entry => entry.age)

To calculate the average age of all users, you can then streamline the filtered array using reduce to obtain a single value, which is then divided by the total length of the array. This operation can be executed in just one line of code.

const averageAge = users.filter(entry => entry.age).reduce((sum, entry) => sum + entry.age, 0) / users.length

Answer 4

If you want to achieve specific objectives, you can utilize functions such as filter, map, and reduce.

For ensuring the existence of keys, you can filter out entries that do not contain those keys:

// Filter out entries without the age property
const validUsers = users.filter(entry => entry.age)

To calculate the average age of all users, you can then streamline the filtered array using reduce to obtain a single value, which is then divided by the total length of the array. This operation can be executed in just one line of code.

const averageAge = users.filter(entry => entry.age).reduce((sum, entry) => sum + entry.age, 0) / users.length

JavaScript: A guide to calculating the average of a JSON array using certain criteria within the keys/fields

Answer №1

Answer №2

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