Typescript array from map sorted by value?

Question

I am trying convert a map into a sorted array. There are millions of solutions around, all of which result in one of many many many different errors.

I want to sort this:

public midiCcs: Map<string, ControllerInfo> = new Map<string, ControllerInfo>();

into an array of ControllerInfo ordered by ccMsb:

export class ControllerInfo {
    public name: string = "unassigned";
    public ccMsb: number = 0;
    public ccLsb: number = 0;
    public max: number = 127;
    public min: number = 0;

    constructor(jsonObject: any) {
        this.name = jsonObject.name;
        this.ccMsb = jsonObject.ccMsb;
        this.ccLsb = jsonObject.ccLsb;
        this.max = jsonObject.max;
        this.min = jsonObject.min;
    }

    public toString = () => {
        return `ControllerInfo ${this.name} ${this.min} to ${this.max} ccMsb ${this.ccMsb} ccLsb ${this.ccLsb}`
    }
}

Would greatly appreciated a way out of this minefield.

[ ...midiCcs.values() ].sort((a, b) => a.ccMsb - b.ccMsb) -- looks good? — alx
– alx, Commented Sep 14, 2022 at 8:20

mbojko · Accepted Answer · 2022-09-14 08:24:06Z

1

I'm assuming you want to keep the string label. It could be something like this:

Array.from(midiCcs)
    .sort(([label1, item1], [label2, item2]) => item1.ccMsb - item2.ccMsb);

edited Sep 14, 2022 at 8:24

answered Sep 14, 2022 at 8:20

mbojko

14.8k2 gold badges21 silver badges28 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Nick Vu · Accepted Answer · 2022-09-14 08:42:38Z

0

You can try this approach with sort() (to sort Map by keys) and values() (to get values from Map).

class ControllerInfo {
    public name: string = "unassigned";
    public ccMsb: number = 0;
    public ccLsb: number = 0;
    public max: number = 127;
    public min: number = 0;

    constructor(jsonObject: any) {
        this.name = jsonObject.name;
        this.ccMsb = jsonObject.ccMsb;
        this.ccLsb = jsonObject.ccLsb;
        this.max = jsonObject.max;
        this.min = jsonObject.min;
    }

    public toString = () => {
        return `ControllerInfo ${this.name} ${this.min} to ${this.max} ccMsb ${this.ccMsb} ccLsb ${this.ccLsb}`
    }
}

const midiCcs: Map<string, ControllerInfo> = new Map<string, ControllerInfo>([
    ["C", new ControllerInfo({ name: "C" })],
    ["A", new ControllerInfo({ name: "A" })],
    ["B", new ControllerInfo({ name: "B" })]
]);

const notSortedArray: ControllerInfo[] = Array.from(midiCcs.values());

console.log(notSortedArray)

//shorter version in short()
//const sortedArray: ControllerInfo[] = Array.from(new Map(Array.from(midiCcs).sort()).values());

const sortedArray: ControllerInfo[] = Array.from(new Map(Array.from(midiCcs).sort(([key1], [key2]) => key1.localeCompare(key2))).values());

console.log(sortedArray)

Playground

edited Sep 14, 2022 at 8:42

answered Sep 14, 2022 at 8:27

Nick Vu

15.6k5 gold badges29 silver badges37 bronze badges

9 Comments

VLAZ Over a year ago

[...midiCcs].sort()] makes no sense. It's a very roundabout way of sorting by key but also very error-prone way to do that. And most definitely doesn't sort anything (either values or entries) by ccMsb. Moreover, new Map([...midiCcs].sort()).values() is also a roundabout way of getting the values sorted by their key. If that's the intention then Array.from(map).sort((key1], [key2]) => key1.localeCompare(key2)).map(([, value]) => value) is 1. more correct 2. more direct.

Nick Vu Over a year ago

Hmm I think it's no harm to use shortcut, but for maintenance, it's important for making the code readable, agreed with you on this.

VLAZ Over a year ago

Why sort the array of entries, then create a map, and then also extract the values from the map to turn them back into an array? What is the purpose of jumping through so many hoops?

VLAZ Over a year ago

Also, this is still only sorting by keys. Not, as the question has asked from the very beginning, property of the value.

ohthepain Over a year ago

I think I am creating my map incorrectly from the server response. midiChart.midiCcs.values() gives me an error "TypeError: midiChart.midiCcs.values is not a function" even though JSON.stringify(midiChart.midiCcs) looks correct.

|

Collectives™ on Stack Overflow

Typescript array from map sorted by value?

2 Answers 2

Comments

9 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

9 Comments

Your Answer

Sign up or log in

Post as a guest