Array of values. Set minimum value to 0%, maximum value to 100% and find coefficient for all items

Question

I am trying to find a solution with my task for several hours straight without real improvements, so I will try to seek help from you.

Let's say, we have an array with values.

let values = [1000, 2000, 3000, 4000, 5000];
let maxValue = Math.max(...values);
let minValue = Math.min(...values);
values.map((item) => ((item) / maxValue));

As you can see, we are receiving [0.2, 0.4, 0.6, 0.8, 1], but what I want is to receive array like [0, 0.25, 0.5, 0.75, 1] out of it.

My logic is kinda shocked with this challenge, so I hope you could help me. I tried to set first value to 0 and last value to 1, but still nothing. Tried, to play with (item-minValue) / maxValue also, we are receiving first value as a 0, but it doesn't help.

Answer 1

Please take a look at following code which focusses on finding a value that can be added to output array [0, 0.2, 0.4, 0.6, 0.8] to make it [0, 0.25, 0.5, 0.75, 1]. Also it will always work on sorted arrays.

let values = [1000, 2000, 3000, 4000, 5000];
let maxValue = Math.max(...values);
let minValue = Math.min(...values);
const fractionsArr = values.map((item) => ((item-minValue) / maxValue));
const coefficient = (1 -fractionsArr[fractionsArr.length-1]) / (fractionsArr.length - 1)
return fractionsArr.map((item, index) => item + index * coefficient);

OR

let values = [1000, 2000, 3000, 4000, 5000];
let maxValue = Math.max(...values);
let minValue = Math.min(...values);
return values.map((item) => ((item-minValue) / (maxValue - minValue)));

Answer 2

You need to subtract the minValue from both item and maxValue when mapping the values:

let values = [1000, 2000, 3000, 4000, 5000];
let maxValue = Math.max(...values);
let minValue = Math.min(...values);
values.map((item) => ((item - minValue) / (maxValue - minValue)));