W#02 Data Visualization, Data Formats

Jan Lorenz

Git and GitHub

Git the version control system
- somehow like Track Changes in Microsoft Word
- somehow like “Save as …” for multiple files in a folder (with old versions saved)
Developed 2005 by Linus Torvalds to maintain the Linux kernel

GitHub our home for Git-based projects on the internet – a bit like DropBox but for code files
The platform for web hosting, collaboration, and as our course management system in this course

Our toolkit once again

Our git-GitHub dance

Happens with thw GitHub-Organization CU-F23-MDSSB-MET-03-VisCommDataStory

Our git-GitHub dance

We only use only a few of the various git commands.¹

Our git-GitHub dance

You git clone your private repositories to your computer.

Our git-GitHub dance

git add, git commit, git push your work, git pull other’s work

Programming languages

Definition: Systems of rules which can process instructions to be executed by the computer.

Our two programming languages are:

In R:

do_this(to_this)
do_that(to_this, with_those)
to_this |> do_this() |> do_that(with_those) 
store <- do_that(to_this)

In python:

to_this.do_this()
to_this.do_this(with_those)
to_this.do_this().do_that(with_those)
store = do_that(to_this)

The role of brackets, dots, spaces, special words, and so on is the syntax of a language. Wrong syntax is a common cause of error. Learning syntax slows you down, but only initially!
Essential part of the game: Installing and using libraries/packages. In R:
install.packages("tidyverse") (called once to install) and
library(tidyverse) (in the code before using its commands)

Integrated development environment

IDEs provide terminals, a source code editor, an object browser (the environment), output and help view, tools for rendering and version control, and more to help in the workflow. Our IDEs are:

VS Code

Editors delight us with

syntax highlighting Then we see if code looks good

c(1O, Text, true, 10,"Text",TRUE)

code completion Start writing, and press Tab to see options
automatic indentation, brace matching, keyboard shortcuts, …

Learn to customize and use IDEs ever better and better!

Publishing system

Weaves together text and code to produces good-looking formatted scientific or technical output.

A YAML header and Markdown text with code chunks is rendered to a document in several formats.

Notebooks are a similar concept: text and executable code mixed together in a browser tab. Notebooks (e.g. .ipynb-files) Can be rendered by quarto. Popular in the python world.

Main difference between notebook and quarto-output: Code in the notebook can be executed. The page is not static.

quarto Documents

Header: YAML with title, author, document-wide specifications

Body:

Parts of plain text with formatting syntax like **bold** for bold, and other for headers, lists, and so on. Good idea: Occassionally spend a few minutes to look up and learn some formatting rules for markdown.
Code chunks where the programming happens!
- Beginning with ```{r}
- Then optional chunk specifications. For example
  - #| label: NAME to cross-reference to it in the text
  - #| echo: false to not show (or show if true) code in output
  - #| warning: false to not show (or show if true) the the warnings you would see in the Console
- Then comes the code itself. By default, every command which creates some print output or shows a graphic will make this appear in your output-document.
- Ending with ```

What is an Enviroment, and why you should know it

Environment can be understood as the surrounding conditions in which code is executed.
- In RStudio: There is an Environment-Tab.
- Most important: Shows the variables currently accessible from the Console.
The environment of your quarto document is different for that of the Console! Remember this! It will be a source of confusion.