# Thread: calculating the average/mean

1. ## calculating the average/mean

Hi,

Im trying to calculate the mean/average of numbers in an array any suggestions with the mean() would be very much appreciated.

how can i get the length of an array to perform in a simple / maths problem whilst being flexiable to the length of the array?

function sum()
{
var i=0
for (i=0, total=0;i <numbers.length; i++)
{
total += numbers[i];
}
document.getElementById("txtTotal").value = total;
}

function mean()
{

document.getElementById("answer") = parseFloat(document.getElementById("txtTotal").value) / parseFloat(numbers.length);
}

2. Try this.
Code JavaScript:
``` var numberArray=[1,2,3,4,5], thisTotal=0,thisAverage=0;
// add elements of array together
for(var i=0;i<numberArray.length;i++)
{thisTotal+=numberArray[i];}
// calculate average
thisAverage=(thisTotal/numberArray.length);
// display result

3. I've whipped up some functions that calculate mean, median, mode, and range.

Code javascript:
```
function mean(numbers) {
// mean of [3, 5, 4, 4, 1, 1, 2, 3] is 2.875
var total = 0,
i;
for (i = 0; i < numbers.length; i += 1) {
total += numbers[i];
}
}
function median(numbers) {
// median of [3, 5, 4, 4, 1, 1, 2, 3] = 3
var median = 0,
numsLen = numbers.length;
numbers.sort();
if (numsLen % 2 === 0) { // is even
// average of two middle numbers
median = (numbers[numsLen / 2 - 1] + numbers[numsLen / 2]) / 2;
} else { // is odd
// middle number only
median = numbers[(numsLen - 1) / 2];
}
return median;
}
function mode(numbers) {
// as result can be bimodal or multimodal,
// the returned result is provided as an array
// mode of [3, 5, 4, 4, 1, 1, 2, 3] = [1, 3, 4]
var modes = [],
count = [],
i,
number,
maxIndex = 0;
for (i = 0; i < numbers.length; i += 1) {
number = numbers[i];
count[number] = (count[number] || 0) + 1;
if (count[number] > maxIndex) {
maxIndex = count[number];
}
}
for (i in count) if (count.hasOwnProperty(i)) {
if (count[i] === maxIndex) {
modes.push(Number(i));
}
}
return modes;
}
function range(numbers) {
// range of [3, 5, 4, 4, 1, 1, 2, 3] is [1, 5]
numbers.sort();
return [numbers[0], numbers[numbers.length - 1]];
}```

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