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R

LiveCodes runs R statistical programming language in the browser using WebR.

WebR is a version of the statistical language R compiled for the browser and Node.js using WebAssembly, via Emscripten.

WebR makes it possible to run R code in the browser without the need for an R server to execute the code: the R interpreter runs directly on the user’s machine. Several R packages have also been ported for use with webR, and can be loaded in the usual way.

https://docs.r-wasm.org/webr/

Usage​

Check the starter template for an example.

Loading Packages​

Supported packages can just be loaded in code, using the library() function, without the need for any explicit installs. Packages are publicly hosted via a CDN in a CRAN-like repository with URL, https://repo.r-wasm.org/

Example:

Output Rendering​

By default, the R code is evaluated and the output is rendered in the document.body of the result page, followed by the plots (rendered as HTML canvas elements).

The evaluation and rendering behavior can be configured by adding a script element in the HTML (markup editor) and setting livecodes.r.config.

Example:

HTML
<div id="output"></div>

<script>
  livecodes.r.config = {
    container: document.querySelector('#output'),
    // other options
  };
</script>

The following configurations are supported:

  • container: CSS selector of the element in which the R code is rendered. If not specified, the output is rendered in document.body. If set to null, the output is not rendered automatically, and can then be accessed via livecodes.r.output (see below).
  • canvasHeight: a number representing the height of the output canvas in pixels. Defaults to 309.
  • canvasWidth: a number representing the width of the output canvas in pixels. Defaults to 500.
  • canvasPointSize: a number representing the plots point size. Defaults to 12.
  • canvasBackground: a string representing the plots background color. Defaults to "transparent".
  • autoEvaluate: a boolean indicating whether the R code is evaluated automatically. Defaults to true.

In addition, detecting and triggering evaluation can be controlled using:

  • livecodes.r.evaluated: a promise that can be awaited to denote when the R code has been evaluated when livecodes.r.config.autoEvaluate is set to true.
  • livecodes.r.run(): an async method that triggers the evaluation of the R code. This is useful when livecodes.r.config.autoEvaluate is set to false. It may take an optional parameter representing the config object (see above)

The output and plots can be accessed via:

  • livecodes.r.output: a string representing the output of the R code.
  • livecodes.r.plots: an array of HTML canvas elements representing the plots.

These are available after the promise livecodes.r.evaluated or that returned by livecodes.r.run() is resolved

Examples​

This example shows how to specify the container (for output and plots):

HTML
<div id="container"></div>

<script>
  livecodes.r.config = {
    container: document.querySelector('#container'),
  };
</script>

This example shows how to specify different containers for output and plots:

HTML
<h2>Output</h2>
<div id="output"></div>
<h2>Plots</h2>
<div id="plots"></div>

<script type="module">
  livecodes.r.config = {
    container: null,
  };

  await livecodes.r.evaluated;

  const pre = document.createElement('pre');
  pre.innerHTML = livecodes.r.output;
  document.querySelector('#output').appendChild(pre);

  document.querySelector('#plots').appendChild(...livecodes.r.plots);
</script>

This example shows how to control when to trigger evaluation of the R code.:

HTML
<h2>Output</h2>
<div id="output"></div>
<h2>Plots</h2>
<div id="plots"></div>

<script type="module">
  livecodes.r.config = {
    container: null,
    autoEvaluate: false,
  };

  await livecodes.r.run();

  const pre = document.createElement('pre');
  pre.innerHTML = livecodes.r.output;
  document.querySelector('#output').appendChild(pre);

  document.querySelector('#plots').appendChild(...livecodes.r.plots);
</script>

Demo​

show code
import { createPlayground } from 'livecodes';

const options = {
  "params": {
    "r": "head(iris)\n\nPW <- iris$Petal.Width\nPL <- iris$Petal.Length\nspecies <- iris$Species\nspeciesID <- as.numeric(species)\n\nplot(PL, PW,\n     pch = speciesID,\n     col = speciesID,\n     main = \"Petal Width vs Length\",\n     xlab = \"Petal Length\",\n     ylab = \"Petal Width\")\nlegend(\"topleft\",\n       levels(species),\n       pch = 1:3,\n       col = 1:3)\n",
    "html": "<h2>Output</h2>\n<div id=\"output\"></div>\n<h2>Plots</h2>\n<div id=\"plots\"></div>\n\n<script type=\"module\">\n  livecodes.r.config = {\n    container: null,\n  };\n\n  await livecodes.r.evaluated;\n\n  const pre = document.createElement('pre');\n  pre.innerHTML = livecodes.r.output;\n  document.querySelector('#output').appendChild(pre);\n\n  document.querySelector('#plots').appendChild(...livecodes.r.plots);\n</script>\n",
    "activeEditor": "script"
  }
};
createPlayground('#container', options);

Language Info​

Name​

r

Extension​

.r

Aliases​

rlang, rstats, r-wasm

Editor​

script

Compiler​

WebR

Version​

WebR v0.2.1, running R v4.3.0

Code Formatting​

Not supported.

Live Reload​

By default, when code is updated, the WebR environment is re-used while the global variables are reset. This behavior is used for performance reasons. However, in order to fully reload WebR and start a new environment, insert this comment in the code:

# __livecodes_reload__

Think of this like restarting the kernel in Jupyter notebooks.

Starter Template​

https://livecodes.io/?template=r

Sponsors