Python Markdown Syntax

Markdown It
Python Markdown Formatting
Python Markdown Syntax

Learning Objectives

Explain what the Markdown format is.
Describe the role of Markdown for documentation of earth data science workflows.
Use Markdown syntax in Jupyter Notebook to:
- Create headers and lists
- Bold and italicize bold text
- Render images and create hyperlinks to web pages

In this video, we show how to use Python to convert markdown to HTML and add Python syntax highlighting. The video was inspired by a blog post. Using Markdown ```Python str = 'This is block level code' print(str) ``` Using Markup Tags Python str = 'This is a block level code' print(str) Using Markdown, you can get the syntax highlighting of code if programming language name is mentioned after.

Markdown is great because of its support of code blocks. We've tied this in with Codebase's powerful syntax highlighting to provide language specific code blocks To use the syntax highlighting, you'll need to specify the language that you're using.
Using Markdown ```Python str = 'This is block level code' print(str) ``` Using Markup Tags Python str = 'This is a block level code' print(str) Using Markdown, you can get the syntax highlighting of code if programming language name is mentioned after the '```' three ticks and the example is given below.

What is Markdown?

Markdown is a human readable syntax (also referred to as a markup language) for formatting text documents. Markdown can be used to produce nicely formatted documents including PDFs and web pages.

When you format text using Markdown in a document, it is similar to using the format tools (e.g. bold, heading 1, heading 2) in a word processing tool like Microsoft Word or Google Docs. However, instead of using buttons to apply formatting, you use syntax such as **this syntax bolds text in markdown** or # Here is a heading.

Markdown syntax allows you to format text in many ways, such as making headings, bolding and italicizing words, creating bulleted lists, adding links, formatting mathematical symbols and making tables. These options allow you to format text in visually appealing and organized ways to present your ideas.

You can use Markdown to format text in many different tools including GitHub.com, R using RMarkdown, and Jupyter Notebook, which you will learn more about this page.

Data Tip: Learn more about how you can use Markdown to format text and document workflows in a variety of tools.

Markdown in Jupyter Notebook

Markdown It

A great benefit of Jupyter Notebook is that it allows you to combine both code (e.g. Python) and Markdown in one document, so that you can easily document your workflows.

A Jupyter Notebook file uses cells to organize content, and it can contain both cells that render text written using the Markdown syntax as well as cells that contain and run Python code.

Thus, you can use a combination of Markdown and Python code cells to organize and document your Jupyter Notebook for others to easily read and follow your workflow.

Data Tip: Learn more about Markdown for Jupyter Notebook.

If you render your Jupyter Notebook file to HTML or PDF, this Markdown will appear as formatted text in the output document.

Data Tip: In fact, this web page that you are reading right now is generated from a Markdown document! On this page, you will learn the basic syntax of Markdown.

Benefits of Markdown for Earth Data Science

Being able to include both Markdown and code (e.g. Python) cells in a Jupyter Notebook file supports reproducible science by allowing you to:

Document your workflow: You can add text to the document that describes the steps of your processing workflow (e.g. how data is being processed and what results are produced).
Describe your data: You can describe the data that you are using (e.g. source, pre-processing, metadata).
Interpret code outputs: You can add some text that interprets or discusses the outputs.

all in one document!

When used effectively, Markdown documentation can help anyone who opens your Jupyter Notebook to follow, understand and even reproduce your workflow.

Format Text in Jupyter Notebook with Markdown

Markdown Cells in Jupyter Notebook

In the previous chapter on Jupyter Notebook, you learned how to add new Markdown cells to your Jupyter Notebook files using Menu tools and Keyboard Shortcuts to create new cells.

Function	Keyboard Shortcut	Menu Tools
Create new cell	Esc + a (above), Esc + b (below)	Insert→ Insert Cell Above OR Insert → Insert Cell Below
Copy Cell	c	Copy Key
Paste Cell	v	Paste Key

You also learned how to change the default type of the cell by clicking in the cell and selecting a new cell type (e.g. Markdown) in the cell type menu in the toolbar. Furthermore, you learned that in a Jupyter Notebook file, you can double-click in any Markdown cell to see the syntax, and then run the cell again to see the Markdown formatting.

Note: if you type text in a Markdown cell with no additional syntax, the text will appear as regular paragraph text. You can add additional syntax to that text to format it in different ways.

On this page, you will learn basic Markdown syntax that you can use to format text in Jupyter Notebook files.

Section Headers

You can create a heading using the pound (#) sign. For the headers to render properly, there must be a space between the # and the header text.

Heading one is denoted using one # sign, heading two is denoted using two ## signs, etc, as follows:

Here is a sample of the rendered Markdown:

Heading Three

Heading Four

Note: the titles on this page are actually formatted using Markdown (e.g. the words Section Headers above are formatted as a heading two).

Lists

You can also use Markdown to create lists using the following syntax:

It will render as follows:

This is a bullet list
This is a bullet list
This is a bullet list

And you can also create ordered lists
by using numbers
and listing new items in the lists
on their own lines

Notice that you have space between the * or 1. and the text. The space triggers the action to create the list using Markdown.

Bold and Italicize

You can also use ** to bold or * to italicize words. To bold and italicize words, the symbols have to be touching the word and have to be repeated before and after the word using the following syntax:

It will render as follows:

These are italicized words, not a bullet listThese are bold words, not a bullet list

This is a bullet item with bold words
This is a bullet item with italicized words

Highlight Code

If you want to highlight a function or some code within a plain text paragraph, you can use one backtick on each side of the text like this:

which renders like this:

Here is some code!

The symbol used is the backtick, or grave; not an apostrophe (on most US keyboards, it is on the same key as the tilde (~)).

Horizontal Lines (Rules)

You can also create a horizontal line or rule to highlight a block of Markdown syntax (similar to the highlighting a block of code using the backticks):

which renders like this:

Here is some important text!

Hyperlinks

You can also use HTML in Markdown cells to create hyperlinks to websites using the following syntax:

<a href='url' target='_blank'>hyperlinked words</a>

You can identify the words that will be hyperlinked (i.e. prompt a web page to open when clicked) by replacing hyperlinked words in the example above.

For example, the following syntax:

Our program website can be found at <a href='http://earthdatascience.org' target='_blank'>this link</a>.

will render as follows with this link as the hyperlinked words:

Our program website can be found at this link.

Render Images

You can also use Markdown to link to images on the web using the following syntax:

![alt text here](url-to-image-here)

The alt text is the alternative text that appears if an image fails to load on webpage; it is also used by screen-reading tools to identify the image to users of the screen-reading tools.

For example, the following syntax:

![Markdown Logo is here.](https://www.fullstackpython.com/img/logos/markdown.png)

will render as follows with an alt text of Markdown Logo is here.:

Local Images Using Relative Computer Paths

You can also add images to a Markdown cell using relative paths to files in your directory structure using:

![alt text here](path-to-image-here)

For relative paths (images stored on your computer) to work in Jupyter Notebook, you need to place the image in a location on your computer that is RELATIVE to your .ipynb file. This is where good file management becomes extremely important.

For a simple example of using relative paths, imagine that you have a subdirectory named images in your earth-analytics directory (i.e. earth-analytics/images/).

If your Jupyter Notebook file (.ipynb) is located in root of this directory (i.e. earth-analytics/notebook.ipynb), and all images that you want to include in your report are located in the images subdirectory (i.e. earth-analytics/images/), then the path that you would use for each image is:

images/image-name.png

If all of your images are in the images subdirectory, then you will be able to easily find them. This also follows good file management practices because all of the images that you use in your report are contained within your project directory.

Data tip: There are many free Markdown editors out there! The atom.io editor is a powerful text editor package by GitHub, that also has a Markdown renderer that allows you to preview the rendered Markdown as you write.

Additional Resources

Practice Your Markdown Skills

Open or create a new Jupyter Notebook file.
Add a new Markdown cell and include:
- A title for the notebook (e.g. Intro to Earth Analytics - Chapter Four)
- A bullet list with:
  - A bold word for Author: and then add text for your name.
  - A bold word for Date: and then add text for today’s date.
Add another Markdown cell and include:
- A list of your top three favorite foods (e.g. blueberries, chocolate bars, avocados).
  - Italicize the first item in your list.
  - Add a hyperlink (i.e. webpages) for the second item in your list (include the name of the food in the title of the hyperlink).
  - Add an image for the last item in your list (include the name in the alt text of the image).

When I first started working on my own blog, one of the first things I started working on was getting code syntax highlighting for my entries. I even implemented a hacky article on the topic.

The crux of the challenge is extending Markdown to have a syntax that indicates a block should be highlighted. I'm still pretty comfortable with the syntax I chose:

Its nothing fancy, but it gets the job done. However, my first attempt at extending Python-Markdown to render that syntax correctly was kind of horrific. It worked, I mean it worked okay, but damn if it didn’t munge the entire Python-Markdown library while it did it.

That is a forgivable sin in some situations, but the implementors of Python-Markdown went out of their way to make it extensible... so I felt a bit dirty about it. As I have been working a lot on my blogging software, I decided that now was the time to fix my previous silliness.

Lets get to work.

Step 1: Get a new copy of Markdown

My old copy of Markdown was crippled and in tears after my first modifications, so I had to get a fresh copy. You'll also want to grab a copy of pygments while you're at it.

Step 2: Write the Damn Thing

There is a full-featured example in the Markdown library (search for FOOTNOTE to jump to it), which is a boon. Whenever confusion finds you, go look at it for guidance.

Now we need to make a new module to put our code in. It doesn't (and shouldn't be) in the same file as markdown.py. I named mine code.py, since I have it in a folder named markup. If you are placing yours in a folder with a less suggestive name, you may want to try a better name.

The first thing you need to write is a preprocessor. Preprocessors need to define one function:

The Markdown library splits all the lines on 'n' and then feeds you the result. If you want to operate on the text as a blob, then you have to rejoin it yourself:

So our class is going to be called CodeBlockPreprocessor (catchy, I know), and its going to have this run method:

We walk through all the lines looking for the start to a code block (represented by two consecutive at symbols (@) at the beginning of a line). If we find one, we ignore text until we find a closing block (if there is no closing block, then everything after the opening block will be discarded... a bit ungraceful, but won't allow any undesirables through either). Then we use Pygments to color the code inbetween the start and end, using the lexer indicated on the opening line of the block (for example @@ ruby uses ruby, and @@ html+django uses html+django).

After we finish the run method, we just have to write some generic code, and soon we'll have a clean extension to Python-Markdown.

First we need to do some imports at the top of our file:

then we need to write a simple class that we'll use to control our new preprocessor.

This is about as simple as classes get. You take an instance of the Markdown class, and then you add an instance of CodeBlockPreprocessor to its list of preprocessors (before the HTML_BLOCK_PREPROCESSOR).

Lastly, we need to make a function to call markdown using our new preprocessor.

We create an instance of Markdown, add our extension, and then render away. If we want to we can make it accept arguments from the command line as well:

Although it seem like more effort than it was worth the first time I modified Python-Markdown, its really a well designed library, and a good example of designing libraries so that others can cleanly extend them. Give its code a read sometime.

Hi folks. I'm Will aka @lethain.
If you're looking to reach out to me, here are ways I help.If you'd like to get a email from me, subscribe to my weekly newsletter.

Python Markdown Formatting

I wroteAn Elegant Puzzle.

As well as,Staff Engineer.

Popular

Recent