How do I calcualte the overall average of an array like this: example array:
[[80, 90, 70], [70,80,60],[90,100,80]]
what I am trying right now
for (let i = 0; i < grades.length; i++) {
for (let y = 0; y < grades[i].length; y++) {
lastTotalScore += grades[i[y]];
lastAverageScore = lastTotalScore / grades[i].length;
overallTotalScore += lastAverageScore;
overallAverageScore = overallTotalScore / grades.length;
}
}
Thanks
Calculate the total from all numbers. Divide it with length of total numbers.
Working Sample
const grades = [[80, 90, 70], [70, 80, 60], [90, 100, 80]];
let lastTotalScore = 0;
let length = 0;
for (let i = 0; i < grades.length; i++) {
length += grades[i].length;
for (let y = 0; y < grades[i].length; y++) {
lastTotalScore += grades[i][y];
}
}
console.log(`Average = ${lastTotalScore / length}`);OR
Convert the two dimentional array to a linear structure using Array.flat and calculate its sum by looping with Array.reduce and divide by its length.
Working Sample
const grades = [[80, 90, 70], [70, 80, 60], [90, 100, 80]];
const flatGrade = grades.flat();
const sum = flatGrade.reduce((acc, curr) => acc + curr, 0);
console.log(`Average = ${sum / flatGrade.length}`);flatten the array, and then reduce over the elements adding them up, and then dividing by the length of the flattened array.
const arr = [
[80, 90, 70],
[70, 80, 60],
[90, 100, 80]
];
// Flatten the nested arrays
const flat = arr.flat();
// `reduce` over the numbers, and then divide
// by the number of elements in the array
const avg = flat.reduce((acc, c) => {
return acc + c;
}, 0) / flat.length;
console.log(avg);