Create array of decimal values counting down to 0

Question

In JavaScript/jQuery I'm generating value that can vary but is usually something like 0.12 or 0.25.

I want to generate an array that has a set amount of values (around 10 values or so) and include the number above at the start or end of the array. I want these values to decrease to 0 so for example -

var values = [0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.12]

I'm just not quite sure how to acheive this.

Thanks

So you're saying you want an array of X values evenly spaced between 0 and Y? — cmbuckley, Jan 10 '19 at 15:16
This seems like it could be an XY problem, why do you need this array? What will it be used for? — DBS, Jan 10 '19 at 15:20
I'm sorry the decimal is a claculated probability value for a normal distribution chart so the maths involved to generate that number is complex. All I can say is that I haven;t had a scenario where is goes over 0.3 @Monica Acha — benji_croc, Jan 10 '19 at 15:21
Functionally, this problem is the same as [Create a JavaScript array containing 1…N](https://stackoverflow.com/questions/3746725/create-a-javascript-array-containing-1-n). — cmbuckley, Jan 10 '19 at 16:17

score 0 · Answer 1 · answered Jan 10 '19 at 15:24

0

You could likely solve this with Array.from:

function sequence(len, max) {
    return Array.from({length: len}, (v, k) => (k * max / (len - 1)).toFixed(2));
}

console.log(sequence(7, 0.12));

answered Jan 10 '19 at 15:24

cmbuckley

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I added `toFixed(2)` in case the floating point issue was a problem for you, but it's quite possible you could remove that entirely. – cmbuckley Jan 10 '19 at 15:27
Thanks @cmbuckley I'm getting an issue/error with both v and k not being defined. I'm sure I'm being a dummy about it but just need some clarification – benji_croc Jan 10 '19 at 15:33
It's quite possible that's a JavaScript version issue. – cmbuckley Jan 10 '19 at 16:17
If you're running into problems with `Array.from`, it may be better to look at other implementations [here](https://stackoverflow.com/questions/3895478/does-javascript-have-a-method-like-range-to-generate-a-range-within-the-supp), or at [Create a JavaScript array containing 1…N](https://stackoverflow.com/questions/3746725/create-a-javascript-array-containing-1-n). underscore.js also has a [`_.range`](https://underscorejs.org/#range) function. – cmbuckley Jan 11 '19 at 10:31

score 0 · Answer 2 · answered Jan 10 '19 at 15:45

An alternative approach could be creating a new array of the predefined length, and then use map() to fill the array with the expected values:

const createSeq = (len, val) =>
{
    return new Array(len).fill(0).map((x, i) => val / (len - 1) * i);
}

console.log(createSeq(7, 0.12));
console.log(createSeq(10, 0.25));

Create array of decimal values counting down to 0

2 Answers2