timeseries-client

Introduction

This package allows you to consume air quality time series fragments.

Prerequisites

Currently, in order to be able to query data fragments, a local running instance of an AirQualityServer is required. The code for this server can be acquired from https://github.com/sigvevermandere/AirQualityExpressServer. Instructions on how to setup the server can also be found there.

Install it

Clone this repository and run npm install. To run in the browser, run npm run webpack to generate a file bundle.js and import it into your project.

How to use it

The main method here is getPolygonObservations in the DataFetcher class, which has the following parameters:

geometry: Array<{lat: number, lng: number}>,
fromDate: (Date | string),
toDate: (Date | string),
aggrMethod?: string,
aggrPeriod?: string

geometry contains the area over which data will be requested and is defined as an array of coordinates. fromDate and toDate define the time interval over which data will be requested. aggrMethod and aggrPeriod are two optional parameters that define an aggregation method and period that can be applied to the data. Currently, possible values for aggrMethod are average and median. Possible values for aggrPeriod are min, hour and day.

This method will asynchronously request all data within the given area and time interval, starting at the back of the time interval and going to the front. Queried data is stored in the DataFetcher class and can be queried with getCurrentObservations(metric: string), where metric is the air quality metric for which the data will be returned. To get all the data, use getAllCurrentObservations.

To be notified when new data arrives, methods can subscribe to the datafetcher using addFragmentListener(method: CallableFunction). The datafetcher will execute each subscriber every time a request is completed and pass the startDate, endDate and previous properties of the completed request.

Example:

let datafetcher = new TimeSeriesClientSide.DataFetcher();
// Subscribe a method
datafetcher.addFragmentListener(showData);
// Request all the data within the given polygon between 8 and 9 November.
datafetcher.getPolygonObservations([{lat: 51.24925948378325, lng: 4.391884628594368},
{lat: 51.24914009674451, lng: 4.420790593889175},
{lat: 51.23307965364257, lng: 4.419932000834682},
{lat: 51.23331851079149, lng: 4.3922662240518004}],
"2019-11-08T00:00:00.000Z",
"2019-11-09T00:00:00.000Z");

// Log all the received data
function showData(data) {
  console.log(datafetcher.getAllObservations());
}

Demo

An interactive demo is available on https://github.com/linkedtimeseries/timeseries-client-demo