TOPIC: LIGHTWEIGHT MARKUP LANGUAGES
Displaying superscripted text in Hugo website content
6th January 2025In a previous post, there was a discussion about displaying ordinal publishing dates with superscripted suffixes in Hugo and WordPress. Here, I go further with inserting superscripted text into Markdown content. Because of the default set up for the Goldmark Markdown renderer, it is not as simple as adding <sup>...</sup> constructs to your Markdown source file. That will generate a warning like this:
WARN Raw HTML omitted while rendering "[initial location of Markdown file]"; see https://gohugo.io/getting-started/configuration-markup/#rendererunsafe
You can suppress this warning by adding the following to your site configuration:
ignoreLogs = ['warning-goldmark-raw-html']
Because JavaScript can be added using HTML tags, there is an added security hazard that could be overlooked if you switch off the warning as suggested. Also, Goldmark does not interpret Markdown specifications of superscripting without an extension whose incorporation needs some familiarity with Go development.
That leaves using a Shortcode. These go into layouts/shortcodes under your theme area; the file containing mine got called super.html. The content is the following one-liner:
<sup>{{ .Get 0 | markdownify }}/sup>
This then is what is added to the Markdown content:
{{< super "th" >}}
What happens here is that the Shortcode picks up the content within the content within the quotes and encapsulates it with the HTML superscript tags to give the required result. This approach can be extended for subscripts and other similar ways of rendering text, too. All that is required is a use case, and the rest can be put in place.
Rendering Markdown into HTML using PHP
3rd December 2022One of the good things about using virtual private servers for hosting websites instead of shared hosting or using a web application service like WordPress.com or Tumblr is that you get added control and flexibility. There was a time when HTML, CSS and client-side scripting were all that was available from the shared hosting providers that I was using back then. Then, static websites were my lot until it became possible to use Perl server side scripting. PHP predominates now, but Python or Ruby cannot be discounted either.
Being able to install whatever you want is a bonus as well, though it means that you also are responsible for the security of the containers that you use. There will be infrastructure security, but that of your own machine will be your own concern. Added power always means added responsibility, as many might say.
The reason that these thought emerge here is that getting PHP to render Markdown as HTML needs the installation of Composer. Without that, you cannot use the CommonMark package to do the required back-work. All the command that you see here will work on Ubuntu 22.04. First, you need to download Composer and executing the following command will accomplish this:
curl https://getcomposer.org/installer -o /tmp/composer-setup.php
Before the installation, it does no harm to ensure that all is well with the script before proceeding. That means that capturing the signature for the script using the following command is wise:
HASH=`curl https://composer.github.io/installer.sig`
Once you have the script signature, then you can check its integrity using this command:
php -r "if (hash_file('SHA384', '/tmp/composer-setup.php') === '$HASH') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"
The result that you want is "Installer verified". If not, you have some investigating to do. Otherwise, just execute the installation command:
sudo php /tmp/composer-setup.php --install-dir=/usr/local/bin --filename=composer
With Composer installed, the next step is to run the following command in the area where your web server expects files to be stored. That is important when calling the package in a PHP script.
composer require league/commonmark
Then, you can use it in a PHP script like so:
define("ROOT_LOC",$_SERVER['DOCUMENT_ROOT']);
include ROOT_LOC . '/vendor/autoload.php';
use League\CommonMark\CommonMarkConverter;
$converter = new CommonMarkConverter();
echo $converter->convertToHtml(file_get_contents(ROOT_LOC . '<location of markdown file>));
The first line finds the absolute location of your web server file directory before using it when defining the locations of the autoload script and the required markdown file. The third line then calls in the CommonMark package, while the fourth sets up a new object for the desired transformation. The last line converts the input to HTML and outputs the result.
If you need to render the output of more than one Markdown file, then repeating the last line from the preceding block with a different file location is all you need to do. The CommonMark object persists and can be used like a variable without needing the reinitialisation to be repeated every time.
The idea of building a website using PHP to render Markdown has come to mind, but I will leave it at custom web pages for now. If an opportunity comes, then I can examine the idea again. Before, I had to edit HTML, but Markdown is friendlier to edit, so that is a small advance for now.
Some books and other forms of documentation on R
11th September 2021The thrust of an exhortation from a computing handbook publisher comes to mind here: don't just look things up on Google, read a book so you really understand what you are doing. A form of words like that was used to sell an eBook on GitHub, but the same sentiment applies to R or any other computing language. While using a search engine will get you going or add to existing knowledge, only a book or a training course will help to embed real competence.
In the case of R, there is a myriad of blogs out there that can be consulted, as well as function and package documentation on RDocumentation or rrdr.io. For the former, R-bloggers or R Weekly can make good places to start, while ones like Stats and R, Statistics Globe, STHDA, PSI's VIS-SIG and anything from Posit (including their main blog as well as their AI one) can be worth consulting. Additionally, there is also RStudio Education and the NHS-R Community, which also have a GitHub repository together with a YouTube channel. Many packages have dedicated websites as well, so there is no lack of documentation with all of these, so here is a selection:
To come to the real subject of this post, R is unusual in that books that you can buy also have companion websites that contain the same content with the same structure. Whatever funds this approach (and some appear to be supported by RStudio itself by the looks of things), there certainly are many books available freely online in HTML as you will see from the list below, while a few do not have a print counterpart as far as I know:
R Programming for Data Science
R Markdown: The Definitive Guide
bookdown: Authoring Books and Technical Documents with R Markdown
blogdown: Creating Websites with R Markdown
pagedown: Create Paged HTML Documents for Printing from R Markdown
Dynamic Documents with R and knitr
Engineering Production-Grade Shiny Apps
Outstanding User Interfaces with Shiny
Happy Git and GitHub for the useR
Outstanding User Interfaces with Shiny
Engineering Production-Grade Shiny Apps
Many of the above have counterparts published by O'Reilly or Chapman & Hall, to name the two publishers that I have found so far. Aside from sharing these with you, there is also the personal motivation of having the collection of links somewhere so I can close tabs in my Firefox session. There are other web articles open in other tabs that I need to retain and share, but these will need to do for now, and I hope that you find them as useful as I do.