Jordi Burgos's avatar

My first Pelican plugin: readtime - Calculate the reading time of the articles

Read in 2 min.

As I have seen in other blogs, I wanted to have a reading time estimation on my articles.

I'm using Pelican as blog engine and it allows to write your own plugins to process articles and pages of your blog. It is developed using Python, check the code on the github repository of readtime.

You can see the results on this screenshot:

Plugin development

The Pelican plugins works with signals, they are like events. You can register a method on the signal interested. The method will be called each time that the signal is emited.

Here you can check the list of signals on the documentation. Each signal has its own parameters and details on when it is called.

The one I used is content_object_init, it is called on each page or article is read. This is how the signal is registered:

from pelican import signals

def register():
    signals.content_object_init.connect(calculate_readtime)

Then, the calculations of the time needed for reading the article are done on the calculate_readtime method. The information is stored on the content_object parameter for later access on the templates.

def calculate_readtime(content_object):
    if content_object._content is not None:
        content = content_object._content

    minutes = ... calculations ...

    content_object.readtime = {
        "minutes": minutes,
    }

Calculations

To calculate the minutes needed, first I need to count the number of words of the article. This is done by stripping all the HTML tags of the content and counting the words.

text = strip_tags(content)
words = re.split(r'[^0-9A-Za-z]+', text)
num_words = len(words)

The other parameter needed is the words per minute taht a person can read. As wikipedia suggests on various articles, Reading process or Words per minute, I stimated that the parameter is 200 words per minute.

WPM = 200.0

And the complex arithmetic.

minutes = int(math.ceil(num_words / WPM))
if minutes == 0:
    minutes = 1

Usage

To use it you have to add the plugin name to the pelicanconf.py file.

PLUGINS=[ ... , 'readtime']

Then you can access the minutes variable to show on your article.html template.

{% if article.readtime %}
<div><b>Read in {{article.readtime.minutes}} min.</b></div>
{% endif %}

Conclusion

It is very easy to create a Pelican plugin. You just need an idea and a little time to add new functionality for your favourite static blog engine.


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