Looping through an array of items and computing the mean value

Question

Looping through an array of items and computing the mean value

Given the current data structure, my goal is to calculate the average value for each column across all items in the contenders object. The next step is to convert this information into an array of arrays. Each subarray should consist of two values: the rounded average of the column and an incremental value starting from 0.

output = [[6, 0], [4, 1], [3, 2], [3, 3], [6, 4]];

Here's an illustration of the input structure:

input = {
  categories: [
    "Cat 1",
    "Cat 2",
    "Cat 3",
    "Cat 4",
    "Cat 5"
  ],
  contenders: {
    item1:       [5, 3, 4, 4, 6],
    item2:       [6, 10, 4, 4, 6],
    item3:       [6, 3, 4, 9, 6],
    item4:       [8, 3, 5, 4, 6],
    item5:       [9, 3, 4, 4, 6],
    item6:       [10, 2, 7, 4, 6],
    item7:       [4, 3, 4, 4, 6],
    item8:       [1, 5, 4, 4, 6]
  },
  misc: [0, 3, 4, 4, 6]
};

I have a function that can handle calculating averages:

function getAvg(data) {
    return data.reduce(function (p, c) {
                return p + c;
            }) / data.length;
}

However, I'm struggling with iterating through the item values to achieve the desired outcome.

javascript

Answer 1

Answer №1

If my understanding is correct and you are looking to calculate an average for each column, where each first element in all arrays within your items keys serves as an example, then the best approach would be to create an array for each column and utilize the average function. However, there is a way to calculate the average without explicitly creating these arrays:

var input = { categories: ["Cat 1", "Cat 2", "Cat 3", "Cat 4", "Cat 5"], contenders: { item1: [5, 3, 4, 4, 6], item2: [6, 10, 4, 4, 6], item3: [6, 3, 4, 9, 6], item4: [8, 3, 5, 4, 6], item5: [9, 3, 4, 4, 6], item6: [10, 2, 7, 4, 6], item7: [4, 3, 4, 4, 6], item8: [1, 5, 4, 4, 6] }, misc: [0, 3, 4, 4, 6] }

var output = []

var cols = input.contenders.item1.length

for(var i=0; i<cols; i++){
  output[i] = [0,i]
}

for(var key in input.contenders){
  var arr = input.contenders[key]
  for(var k = 0; k<cols; k++){
    output[k][0]+=arr[k] 
  }
}

for(var i=0; i<cols; i++){
  output[i][0] = Math.round(output[i][0]/Object.keys(input.contenders).length) 
}

console.log(output)

Answer 2

If my understanding is correct and you are looking to calculate an average for each column, where each first element in all arrays within your items keys serves as an example, then the best approach would be to create an array for each column and utilize the average function. However, there is a way to calculate the average without explicitly creating these arrays:

var input = { categories: ["Cat 1", "Cat 2", "Cat 3", "Cat 4", "Cat 5"], contenders: { item1: [5, 3, 4, 4, 6], item2: [6, 10, 4, 4, 6], item3: [6, 3, 4, 9, 6], item4: [8, 3, 5, 4, 6], item5: [9, 3, 4, 4, 6], item6: [10, 2, 7, 4, 6], item7: [4, 3, 4, 4, 6], item8: [1, 5, 4, 4, 6] }, misc: [0, 3, 4, 4, 6] }

var output = []

var cols = input.contenders.item1.length

for(var i=0; i<cols; i++){
  output[i] = [0,i]
}

for(var key in input.contenders){
  var arr = input.contenders[key]
  for(var k = 0; k<cols; k++){
    output[k][0]+=arr[k] 
  }
}

for(var i=0; i<cols; i++){
  output[i][0] = Math.round(output[i][0]/Object.keys(input.contenders).length) 
}

console.log(output)

Answer 3

Answer №2

To extract each item from the contenders object and generate a new array, you can utilize both Object.keys and map:

function calculateAverage(data) {
  return data.reduce(function (prev, curr) {
    return prev + curr;
  }) / data.length;
} 
var inputData = {
  categories: [
    "Cat 1",
    "Cat 2",
    "Cat 3",
    "Cat 4",
    "Cat 5"
  ],
  contenders: {
    item1:       [5, 3, 4, 4, 6],
    item2:       [6, 10, 4, 4, 6],
    item3:       [6, 3, 4, 9, 6],
    item4:       [8, 3, 5, 4, 6],
    item5:       [9, 3, 4, 4, 6],
    item6:       [10, 2, 7, 4, 6],
    item7:       [4, 3, 4, 4, 6],
    item8:       [1, 5, 4, 4, 6]
  },
  misc: [0, 3, 4, 4, 6]
};
console.log(Object.keys(inputData.contenders).map(function(key, index) {
  return [calculateAverage(inputData.contenders[key]), index];
}));

Answer 4

To extract each item from the contenders object and generate a new array, you can utilize both Object.keys and map:

function calculateAverage(data) {
  return data.reduce(function (prev, curr) {
    return prev + curr;
  }) / data.length;
} 
var inputData = {
  categories: [
    "Cat 1",
    "Cat 2",
    "Cat 3",
    "Cat 4",
    "Cat 5"
  ],
  contenders: {
    item1:       [5, 3, 4, 4, 6],
    item2:       [6, 10, 4, 4, 6],
    item3:       [6, 3, 4, 9, 6],
    item4:       [8, 3, 5, 4, 6],
    item5:       [9, 3, 4, 4, 6],
    item6:       [10, 2, 7, 4, 6],
    item7:       [4, 3, 4, 4, 6],
    item8:       [1, 5, 4, 4, 6]
  },
  misc: [0, 3, 4, 4, 6]
};
console.log(Object.keys(inputData.contenders).map(function(key, index) {
  return [calculateAverage(inputData.contenders[key]), index];
}));

Answer 5

Answer №3

To retrieve the properties, you can utilize Object.keys, and then loop through the values using Array.prototype.forEach.

var data = { teams: ["Team A", "Team B", "Team C"], players: { player1: [6, 8, 7], player2: [9, 4, 7], player3: [5, 6, 7] }, scores: [10, 8, 7] },
    result = [],
    total = [], quantity = [];

Object.keys(data.players).forEach(function (key) {
    data.players[key].forEach(function (value, index) {
        total[index] = (total[index] || 0) + value; 
        quantity[index] = (quantity[index] || 0) + 1;
    });
});
result = total.map(function (value, index) {
    return [Math.round(total[index] / quantity[index]), index]
});

document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');

Answer 6

To retrieve the properties, you can utilize Object.keys, and then loop through the values using Array.prototype.forEach.

var data = { teams: ["Team A", "Team B", "Team C"], players: { player1: [6, 8, 7], player2: [9, 4, 7], player3: [5, 6, 7] }, scores: [10, 8, 7] },
    result = [],
    total = [], quantity = [];

Object.keys(data.players).forEach(function (key) {
    data.players[key].forEach(function (value, index) {
        total[index] = (total[index] || 0) + value; 
        quantity[index] = (quantity[index] || 0) + 1;
    });
});
result = total.map(function (value, index) {
    return [Math.round(total[index] / quantity[index]), index]
});

document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');

Answer 7

Answer №4

It is highly recommended to make use of Object.keys as advised in previous responses. Nevertheless, if for some reason compatibility becomes an issue, you do have the option of creating a string reference to access the desired arrays:

for (var x=1; x<9; x++) { performAction(input.contenders["item"+x]); }

This approach assumes that you already know both the quantity and names of the items beforehand.

Answer 8

It is highly recommended to make use of Object.keys as advised in previous responses. Nevertheless, if for some reason compatibility becomes an issue, you do have the option of creating a string reference to access the desired arrays:

for (var x=1; x<9; x++) { performAction(input.contenders["item"+x]); }

This approach assumes that you already know both the quantity and names of the items beforehand.

Looping through an array of items and computing the mean value

Answer №1

Answer №2

Answer №3

Answer №4

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