I’ve been working with C3.js graphs for an admin website and thought it would be fun to use it on this WordPress blog.  You can use most Javascript libraries in WordPress, but it takes a little more work.  If you know how to write Javascript, then you’ll find that C3.js offers a relatively easy way to create custom pie charts, timeseries charts, line and bar graphs, etc.   Here’s an example of a graph created with C3.js.  I used real historical weather data to compare the record high July 2015 temperatures to average temperatures.

Tacoma, WA: Record High July 2015 Temperatures

Here’s how I created the above graph.

First, I downloaded the c3 and d3 libraries (you can get the zip file on github). I unzipped the file and put the c3.css, c3.min.js, d3.min.js files into the root directory of my wordpress theme.

Side note: I am using a child theme, as you should too, to prevent problems if your theme gets automatically updated.  If you are not familiar with child themes, check out this WordPress tutorial.

Next, I added the following code to my functions.php file:

functions.php

add_action( 'wp_enqueue_scripts', 'add_c3_scripts' );

function add_c3_scripts() {
	$d3_url =  get_stylesheet_directory_uri() . '/d3.min.js';
	$c3_url =  get_stylesheet_directory_uri() . '/c3.min.js';
	$c3_css =  get_stylesheet_directory_uri() . '/c3.css';
	$my_graphs_url =  get_stylesheet_directory_uri() . '/my_graphs.js';
	wp_enqueue_script( 'd3', $d3_url );
	wp_enqueue_script( 'c3', $c3_url, 'd3' );
	wp_enqueue_script( 'my_graphs', $my_graphs_url, 'c3' );
	wp_enqueue_style( 'c3', $c3_css );
}

Next, I create the my_graphs.js file in the root directory of my theme.  For better organization, you could put this in a scripts folder and change the above url accordingly.

In the my_graphs.js file, I write a Javascript function which creates a C3 chart.  It looks like this:

my_graphs.js

function july_2015_graph() {
    var chart = c3.generate({
        bindto: '#july_2015_graph',
        color: {
            pattern: ['#396ab1', '#cc2529']
        },
        data: {
            x: 'x',
            columns: [
                ['x', 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 ,16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31],
                ['Average', 69, 70, 70, 70, 71, 71, 71, 71, 72, 72, 72, 72, 72, 73, 73, 74, 74, 75, 75, 75, 76, 76, 76, 76, 76, 76, 76, 76, 75, 75, 75]
            ],
            type: 'spline'
        },
        axis: {
            x: {
                label: 'Date'
            },
            y: {
                label: 'Temperature (F)',
                min: 65,
                max: 95
            }
        },
        transition: {
            duration: 100
        }
    });

    setTimeout(function () {
        chart.load({
            columns: [
                ['2015', 89, 92, 92, 91, 91, 84, 83, 87, 81, 71, 72, 78, 79, 81, 80, 79, 80, 91, 94, 80, 75, 74, 77, 75, 71, 71, 75, 81, 88, 92, 95]
            ]
        });
    }, 1000);

}

The “bindto:” line at the top of that code segment tells the c3.js Javascript Library where to put the graph.

To display the graph in this post, I edit the post in “text” mode (select the text tab at the top of the wordpress post editor) and add this code:

<div id="july_2015_graph"></div>
<script type="text/javascript">
july_2015_graph();
</script>

For more information about how to use Javascript with WordPress, check out this page: Using Javascript in WordPress