CODEWITHSUNDEEP
javascript
user13518368
user13518368

Reputation: 117

How to calculate percentage of width from value between min and max numbers?

I am struggling with simple problem. What is elegant way of achieving this.

I have 2 values minimum and maximum which can be positive or negative and a third value which is between them. Now I want to calculate position(percentage) of other given number, which in my case is the width of element.
For example here I want to find what is position in the range 0-200 that represents value -10 in range -500 to 600 ?

var min = -500;
var max = 600;
var value = -10;

var width = 200; 

var positionInWidth = ???;

Upvotes: 2

Views: 854

Answers (2)

Benjamin Gruenbaum
Benjamin Gruenbaum

Reputation: 276306

You can one-liner this but let's do this in a few steps to see how it works:

enter image description here

// first we get the total range
var length = max - min; // 1100
// then we offset the position by the start position
var positionInLength = value - min; // 490
// now we get the percent through the value is in the position
var valuePercent = positionInLength / length;
// or a one liner (value - min) / (max - min);
// Then finally, apply `width percentage`
const positionInWidth = width * valuePercent;

Or as a one liner:

const positionInWidth = width * ((value - min) / (max - min));

Upvotes: 4

Monty
Monty

Reputation: 21

So if I understand the question correctly, you are looking for the so called map function. If that's the case, the implementation is as given:

function map(input, inMin, inMax, outMin, outMax) {
    return (input - inMin) * (outMax - outMin) / (inMax - inMin) + outMin;
}

In your scenario outMin = 0:

console.log(map(-10, -500, 600, 0, 200)); // === 89.0909090909091

Upvotes: 1

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