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A Dash Graph component modified to support use of input to extend and/or add traces.

Project description


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dash-extendable-graph is a Dash component library. This library contains a single component: ExtendableGraph. The component is a fork of the Graph() component from dash-core-components (version 1.3.1). Best efforts will be made to keep in sync with the upstream repository.

The primary differentiation between ExtendableGraph and Graph components is the extendData callback. This component has been modified to follow an api that matches the format of figure['data'] (as opposed to the api defined Graph.extendData and Plotly.extendTraces()).

Note: As of version 1.1.0, dash-extendable-graph includes PlotlyJS as an internal dependency. Previously, the component assumed it would be used in conjunction with dash-core-components. As of dash-core-components version ^1.4.0, PlotlyJS is only available asynchronously when a Graph component exists on the page.


Get started with:

  1. Install Dash and dependencies:
$ pip install -r requirements.txt
  1. Install dash-extendable-graph
$ pip install dash-extendable-graph
  1. Run python
  2. Visit http://localhost:8050 in your web browser


General examples may be found in

extendData properties

  1. updateData [list]: a list of dictionaries, each dictionary representing trace data in a format matching figure['data'] (e.g dict(x=[1], y=[1]))
  2. traceIndices [list, optional]: identify the traces that should be extended. If the specified trace index does not exist, a (new) corresponding trace shall be appended to the figure.
  3. maxPoints [number, optional]: define the maximum number of points to plot in the figure (per trace).

Based on the Plotly.extendTraces() api. However, the updateData key has been modified to better match the contents of Plotly.plot() (e.g. Graph.figure). Aside from following dash-familiar styling, this component allows the user to extend traces of different types in a single call (Plotly.extendTraces() takes a map of key:val and assumes all traces will share the same data keys).


Extend a trace once per second, limited to 100 maximum points.

import dash_extendable_graph as deg
import dash
from dash.dependencies import Input, Output, State
import dash_html_components as html
import dash_core_components as dcc
import random

app = dash.Dash(__name__)

app.scripts.config.serve_locally = True
app.css.config.serve_locally = True

app.layout = html.Div([
            data=[{'x': [0],
                   'y': [0],

@app.callback(Output('extendablegraph_example', 'extendData'),
              [Input('interval_extendablegraph_update', 'n_intervals')],
              [State('extendablegraph_example', 'figure')])
def update_extendData(n_intervals, existing):
    x_new = existing['data'][0]['x'][-1] + 1
    y_new = random.random()
    return [dict(x=[x_new], y=[y_new])], [0], 100

if __name__ == '__main__':



Local Installation

  1. Dependencies
$ npm install
$ virtualenv venv
$ . venv/bin/activate
$ pip install -r requirements.txt

For developers:

$ pip install -r tests/requirements.txt
  1. Build
$ npm run build
  1. Check out the component via component-playground
$ npm run start
The demo app is in `src/demo`
  1. Check out the sample Dash application using the component
$ python install
$ python


Run locally

Run linting + integration tests in one command:

$ npm run test

Or run tests individually:

Code style

Uses flake8, eslint, and prettier. Check package.json, .eslintrc, .eslintignore for configuration settings.

$ npm run lint

Also you can apply formatting settings.

$ npm run format


Integration tests for the component can be found in tests/

$ pytest

Selenium test runner configuration options are located in pytest.ini (e.g. --webdriver, --headless). See dash[testing] documentation for more information on built-ins provided by the dash test fixture.

Run individual integration tests based on the filename.

$ pytest tests/

Continuous Integration via Github Actions

This repository uses github actions to automate testing. CI is triggered for each pull request into the master branch


Create a production build and publish:

$ rm -rf dist
$ npm run build
$ python sdist bdist_wheel
$ twine upload dist/*
$ npm publish

Test your tarball by copying it into a new environment and installing it locally:

$ pip install dash_extendable_graph-X.X.X.tar.gz

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