vega-dataflow

What is vega-dataflow?

The vega-dataflow npm package is a JavaScript library for building reactive dataflow graphs. It is a core component of the Vega visualization grammar, enabling the construction of data processing pipelines that can react to changes in data, parameters, or user interactions.

What are vega-dataflow's main functionalities?

Data Transformation

This feature allows you to apply transformations to data. In this example, a filter transformation is applied to filter out data values less than or equal to 10.

const vega = require('vega-dataflow');
const df = new vega.Dataflow();
const data = df.add([]);
const transform = df.add(vega.transforms.Filter, {expr: 'datum.value > 10', pulse: data});
df.pulse(data, vega.changeset().insert([{value: 5}, {value: 15}])).run();
console.log(transform.value); // [{value: 15}]

Reactive Dataflow

This feature allows you to create reactive dataflow graphs that automatically update when data changes. In this example, an aggregate transformation is used to compute the sum of data values.

const vega = require('vega-dataflow');
const df = new vega.Dataflow();
const data = df.add([]);
const sum = df.add(vega.transforms.Aggregate, {fields: ['value'], ops: ['sum'], pulse: data});
df.pulse(data, vega.changeset().insert([{value: 5}, {value: 15}])).run();
console.log(sum.value); // [{sum_value: 20}]

Parameter Binding

This feature allows you to bind parameters to transformations, making them dynamic and reactive to parameter changes. In this example, a filter transformation is bound to a parameter, and the filter condition updates when the parameter changes.

const vega = require('vega-dataflow');
const df = new vega.Dataflow();
const param = df.add(10);
const data = df.add([]);
const transform = df.add(vega.transforms.Filter, {expr: 'datum.value > param', pulse: data});
df.pulse(data, vega.changeset().insert([{value: 5}, {value: 15}])).run();
console.log(transform.value); // [{value: 15}]
df.update(param, 20).run();
console.log(transform.value); // []

Other packages similar to vega-dataflow

d3

D3.js is a JavaScript library for producing dynamic, interactive data visualizations in web browsers. It uses HTML, SVG, and CSS. While D3 focuses on data-driven document manipulation and visualization, vega-dataflow is more about building reactive data processing pipelines.

rx

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lodash

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