JavaScript Charts for ArcGIS
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README.md

@esri/cedar

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JavaScript Charts for ArcGIS

cedar

Cedar is a library for crafting and sharing data visualizations that:

  • are powered by data from ArcGIS maps, scenes, and services
  • include smart default visualization choices
  • can be customized to meet your specific needs

See below for how to get started, understand cedar's core concepts, or see demos of cedar in action.

You are looking at the documentation for v1.x of cedar (which is in beta), you can also view the documentation for v0.x of cedar.

Getting Started

Installing Cedar

NOTE: If you want to use cedar in an Ember.js application, see ember-cli-cedar instead.

You can install cedar and it's dependencies from npm:

npm install @esri/cedar

or yarn:

yarn add @esri/cedar

Alternatively, you can get cedar from the unpkg.com CDN as shown below.

Loading Cedar

You can load Cedar and its dependencies by including script tags that point to the CDN or your locally installed versions of these libraries. This will make the cedar global available to your application.

<!-- load the amCharts base library -->
<script src="https://www.amcharts.com/lib/3/amcharts.js"></script>
<!-- in this case, we only need bar charts, so we'll load the appropriate amCharts script -->
<script src="https://www.amcharts.com/lib/3/serial.js"></script>
<!-- load the arcgis-rest-js scripts -->
<script src="https://unpkg.com/@esri/arcgis-rest-request"></script>
<script src="https://unpkg.com/@esri/arcgis-rest-feature-service"></script>
<!-- optionally load an amcharts theme; cedar provides a calcite theme -->
<script src="https://unpkg.com/@esri/cedar/dist/umd/themes/amCharts/calcite.js"></script>
<!-- load cedar -->
<script src="https://unpkg.com/@esri/cedar/dist/umd/cedar.js"></script>

If you need to use other chart types, or want to use amCharts plugins, load the appropriate amCharts scripts before loading cedar:

<!-- for pie charts -->
<script src="https://www.amcharts.com/lib/3/pie.js"></script>
<!-- for scatter and bubble charts -->
<script src="https://www.amcharts.com/lib/3/xy.js"></script>
<!-- for radar charts -->
<script src="https://www.amcharts.com/lib/3/radar.js"></script>
<!-- optioinally load the amcharts plugin to export the chart as and image or table -->
<script src="https://www.amcharts.com/lib/3/plugins/export/export.min.js"></script>
<link rel="stylesheet" href="https://www.amcharts.com/lib/3/plugins/export/export.css" type="text/css" media="all" />

Using Cedar

Once cedar is loaded you can create and show the chart at a designated element. First create the element:

<div id="chart" style="height: 400px;"></div>

Then add a script that will configure cedar and render the chart:

<script>
  // connect to the data
  var datasets = [{
    "url": "https://services.arcgis.com/uDTUpUPbk8X8mXwl/arcgis/rest/services/Public_Schools_in_Onondaga_County/FeatureServer/0",
    "name": "schools",
    "query": {
      "orderByFields": "Number_of_SUM DESC",
      "groupByFieldsForStatistics": "Type",
      "outStatistics": [{
        "statisticType": "sum",
        "onStatisticField": "Number_of",
        "outStatisticFieldName": "Number_of_SUM"
      }]
    }
  }];

  // designate a one or more series to show the data on the chart
  var series = [{
    "category": {"field": "Type", "label": "Type"},
    "value": {"field": "Number_of_SUM", "label": "Number of Students"},
    "source": "schools"
  }];

  // optionally override any of the cart type's default styles
  var overrides = {
    "categoryAxis": {
      "labelRotation": -45
    }
  }

  //create a cedar chart using the known 'bar' type
  var elementId = 'chart';
  var chart = new cedar.Chart(elementId, {"type": "bar"})
    .datasets(datasets)
    .series(series)
    .overrides(overrides);

  // render the chart
  chart.show();
</script>

See the API documentation for further details on how to work with cedar charts.

Configuring Cedar

You can configure cedar to use a custom implementation of fetch() by setting cedar.config.fetch = myCustomFetch.

Concepts

Components of a Cedar Chart

Cedar charts are built from a definition, which consists of:

  • an array of datasets, each has either:
  • an array of series that bind that data to the plots (bars, lines, points, etc) on the chart
  • and overrides that are specific modifications to the chart type's default styles

Types of Charts

Cedar currently provides a set of commonly used chart types including bar, line, area, scatter, bubble, pie, and radar. In the future it will be possible for developers to create custom charts types that can be used by other developers with their own data sources.

Presentations

Charts and Custom Visualizations Beyond the Map

Slides from the 2018 DevSummit

Video from the 2017 DevSummit

Demos

See this code pen to try creating a simple bar chart like the one above.

You can then see and modify the definitions for different types of charts.

You can also see how to use cedar with the ArcGIS API for JavaScript in these examples:

Dependencies

Cedar isn't yet another JavaScript charting library. Instead, cedar is a very thin wrapper around other libraries that do the heavy lifting. Cedar uses amCharts library as it's charting engine. Cedar also uses @esri/arcgis-rest-feature-service and @esri/arcgis-rest-request to query feature data. You will need to include these libraries along with cedar in your application. If you install cedar using npm or yarn these libraries will be installed for you, but you will have to make sure that your module bundler can resolve and include them in your application. If you are loading cedar from a CDN, please refer to the loading cedar section above for the <script> tags that you will need to include.

Cedar supports the same browsers as ArcGIS Online, however you may need to include polyfills for fetch and Promise, if your application has to support browers that don't support them (i.e. IE or older versions of Safari/Android).

Versioning

For transparency into the release cycle and in striving to maintain backward compatibility, Cedar is maintained under the Semantic Versioning guidelines and will adhere to these rules whenever possible.

Releases will be numbered with the following format:

<major>.<minor>.<patch>

And constructed with the following guidelines:

  • Breaking backward compatibility bumps the major while resetting minor and patch
  • New additions without breaking backward compatibility bumps the minor while resetting the patch
  • Bug fixes and misc changes bumps only the patch

For more information on SemVer, please visit http://semver.org/.

Development Instructions

This repository is a monorepo managed using yarn workspaces and lerna

  1. Fork this repository and clone 'cedar' locally
  2. cd into the cedar folder
  3. Install the dependencies and initialize the monorepo with yarn
  4. to run the docs site locally, start a web server at the root folder and visit /docs
  5. to rebuild the script files used by the docs page whenever the source code is updated, run yarn start

Tests

To run tests one time for all packages, run yarn test from the monorepo root.

To run tests for any package as you update it's source code, cd into that package and run yarn run test:watch to continually run that package's tests as you make your changes.

Licensing

Copyright © 2014-2018 Esri

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

A copy of the license is available in the repository's LICENSE file.