@arction/xydata

XYData generator library

A data generator library.

The generator is used to generate data for LightningChart^® JS charting library. https://www.arction.com/

Installation

npm install --save @arction/xydata

Documentation

Online documentation is available at arction.github.io/xydata

Getting started

import { createProgressiveRandomGenerator } from '@arction/xydata'

// create new instance of progressive random generator
createProgressiveRandomGenerator()
    // define that 1000 points should be generated
    .setNumberOfPoints(1000)
    // generate those 1000 points
    .generate()
    // set stream to progress every 250 milliseconds
    .setStreamInterval(250)
    // set stream to output 10 points at a time
    .setStreamBatchSize(10)
    // make the stream infinite
    .setStreamRepeat(true)
    // create a new stream with previously defined stream settings
    .toStream()
    // every time the stream outputs data, run this function on each of the data points
    .forEach(data=>{
        console.log(data)
    })

This creates a basic progressive random generator and uses the Stream API to output the data to console.

Note: You should newer create a new instance of any generator using the new keyword. Generators should only be created with the create... functions.

When calling .generate() on any data generator a new instance of a 'DataHost' is returned. The .generate() function can be called multiple times to get a new set of data with same settings as before but different values each time.

Creating multiple data sets

You can call .generate() function multiple times to get new sets of data.

import { createTraceGenerator } from '@arction/xydata'

const generator = createTraceGenerator()

const dataSet1 = generator.generate()
const dataSet2 = generator.generate()

This would give you two different data sets that have been generated based on same settings but which will have different values.

Changing generator settings

When a data generator is created it has some default settings based on which generator it is. To change any of these settings call .set.... function that will create a new data generator with that setting changed. You can't change multiple settings with a single call or change settings of a generator that has been created previously. A change in settings will always result in a new generator.

import { createTraceGenerator } from '@arction/xydata'

const generator = createTraceGenerator()
   .setNumberOfPoints( 10 )

const derivedGenerator = generator.setNumberOfPoints( 20 )

const dataSet1 = derivedGenerator.generate()

const dataSet2 = generator.generate()

This would create two data sets with different values and settings. dataSet1 would have 20 data points and dataSet2 would have 10.

Data streams

The data sets have possibility to output the data as a stream of data. These streams can be used to alter the data in multiple steps.

import { createTraceGenerator } from '@arction/xydata'

createTraceGenerator()
   .setNumberOfPoints( 10 )
   .generate()
   .toStream()
   .map( value => ( { x:value.x, y: value.y * 2 } ) )
   .forEach( value => console.log(value) )

This code would create a data generator and then stream that data through two functions, map and forEach. The map function alters the data by multiplying the y value by 2 and then streams it to the forEach function. The forEach function would log each invidual point to console.

The settings for the stream are set by the Data Host that is returned from the .generate() function. The stream settings can't be changed after the stream has been generated.

Generators

Generator	Description
Delta Function	Generate mostly flat data with random spikes.
OHLC	Generate Open, High, Low, Close data.
Parametric Function	Sample user defined X and Y functions for each t step.
Progressive Function	Sample a user defined function with given X step.
Progressive Random	Generate random progressive data that has progessive X step.
Progressive Trace	Generate random trace data from previous point that has progressive X step.
Sample Data	Sample given array with specified frequency and user defined step.
Trace	Generate random trace data that can go to any direction on the XY coordinates.
White Noise	Generate white noise.
Spectrum Data	Generate spectrum data.
Water Drop Data	Generate water drop data.

Development instructions

The project is developed using TypeScript. Build system of the project heavily relies on Node.js. Dependencies are managed with npm, therefore, remember to run npm install before starting of anything else.

The project uses RollUp for creating the distributable library files.

There are several npm scripts, which are used in development process:

Name	Command	Description
test	npm test	run tests and watch
lint	npm run lint	run static analyzer and watch
ci:test	npm run ci:test	run tests once
ci:lint	npm run ci:lint	run static analyzer once
ci:watch	npm run ci:watch	run CI circle and watch
build	npm run build	build the library
build:watch	npm run build:watch	build the library and watch
docs	npm run docs	build documentation

Changelog

[1.4.0] - 2020-01-18

Added

• Water Drop Data Generator.