Posit Cloud ☁️

MATH/COSC 3570 Introduction to Data Science

Dr. Cheng-Han Yu
Department of Mathematical and Statistical Sciences
Marquette University

Let’s get equipped with data science tools!

• All right. Let’s set up our computing environment, so we can start coding, and doing data science.
• The set-up is important. It ensures that you can do what you need to do, including your homework and projects.
• And I would like to make sure everyone is on the same page. OK

Integrated Development Environment

• R and Python are programming languages.

• Posit Cloud offers two integrated development environments (IDE):

  • RStudio
  • JupyterLab/Jupyter Notebook

which are software for efficiently writing computer programs.

• We’ll use Posit Cloud to write R and Python code.
• The first tool we need is Posit Cloud which is a cloud service provided by the company Posit.
• R is not a general-purpose programming language like python or java, but it is specifically for data science. And that’s probably why you don’t learn R in an intro programming course.
• So you can view Python as a smart phone. It can do many different things, phone, camera, email, social media. But R is like a high quality camera. You cannot use it to write emails, text messages, but it produces high quality photos.
• RStudio is not a programming language, but a software application.
• Code itself is just a text file. You can use any text editor or software to write your code.
• So RStudio makes programming in R more easily and efficiently. It provides so many useful functions for you that doing data science becomes a piece of cake.
• Today, You are gonna have a chance to play with different panes and functions in RStudio. OK.

☁️ Posit Cloud - Data Science w/o hardware hassles

• 😎 Implement R/Python programs without needing to install R/Python and the IDE in your laptop!

• 😎 Posit Cloud lets you do, share and learn data science entirely online!

😞 Get everything ready locally: Lots of friction

• Download and install R/Python
• Download and install IDE
• Install wanted R/Python packages:
  • tidymodels
  • tidyverse
  • NumPy
  • …
• Download and install tools like Git

🤓 Posit Cloud: Much less friction

• Go to https://posit.cloud/

• Log in

  > hello world!

• Why I choose posit cloud for you to code in R? Well if I want every one of you use R/Python and RStudio locally in your computer, you have to (_____). And we need some magic to make sure everyone gets the coding environment ready.
• Instead, with the Cloud-based solution, you just need to login, then you start writing code right away.
• Posit Cloud provides you with the latest version of R and RStudio. No installation is required.
• Doesn’t mean you should always use Posit Cloud version. It’s not free if you need more resources.
• If later you program a lot, you should absolutely install them locally into your laptop.

Install Posit Cloud

• Step 1: In the Posit website https://posit.co/, choose Products > Posit Cloud as shown below.

Install Posit Cloud

Step 2: Click GET STARTED.

Step 3: Cloud Student > Sign Up using your Marquette email address.

file:///Users/chenghanyu/Dropbox/academia/books/r/teach-r-online-master/01-cloud/01-cloud.html#37

New Projects

• We will talk about Git/GitHub shortly.

Workspaces

• When you create an account on Posit Cloud you get a workspace of your own.
• You can add a new workspace (click + New Space in sidebar) and control its permissions.

Welcome to 3570 Data Science!

• I’m sending you a link via email for joining the course workspace 2025-spring-math-3570. Please join.

Go to D2l to send Posit Cloud invitation

Subject Posit Cloud Invitation Message https://posit.cloud/spaces/598911/join?access_code=6SiLjVJc37hZPq5Qi6uvzip3vtPCE1z46u0dwKig

Best, Dr. Yu

• In the bar, click workspace 2025-spring-math-3570.

• In the workspace, click New Project > New RStudio Project to get into the IDE.

• In Untitled Project, name your project as 3570-project.

• In the Console pane, write R code: a string "Hello WoRld!" or math 2 + 4.

• Tools > Global Options > Appearance to select your favorite editor theme.

More Tips

• Read the Posit Cloud Documentation

Working in Posit Cloud

Panes

• In RStudio, there are 4 main panes, source pane, console pane, pane for environment/history and version control, and the pane for files plots packages and help page.
• Source pane is where you write your code. Your code will not be evaluated or interpreted until you “run” them or source them to the console.
• Try to write your code in R/Python scripts in the Source, so that the code can be saved and reused later.
• You type code into the Console if the code is short or you want to do some quick calculations or analysis. The code you type in the Console will not be saved in a script.
• In the environment/history, you can check any objects you create in the R/Python environment and you can also view your command history in the history tab.
• And you will see how the pane for file/plot/package/help can be used as we learn more about RStudio.

R Script

• A R script is a .R file that contains R code.

• To create a R script, go to File > New > R Script, or click the green-plus icon on the topleft corner, and select R Script.

• Here you see in this r script, I create two objects x and y, and I also load the data called mtcars into R environment.
• Don’t worry if you don’t know these syntax. I will teach you basic R syntax and programming next week.

Run Code

• Run: run the current line or selection of code.
  • ctrl + enter (Win) or cmd + enter (Mac)
• Icon right to the Run: re-run the previous code.
  • alt + ctrl + p (Win) or option + cmd + p (Mac)
• Source: run all the code in the R script.
  • shift + ctrl + s (Win) or shift + cmd + s (Mac)
• Source with Echo: run all the code in the R script with the code printed in the console.
  • shift + ctrl + enter (Win) or shift + cmd + enter (Mac)

• Source: run all the code in the R script with NO output
• Source with Echo: run all the code in the R script and show output
• Depending on your purpose, you can run code line by line or run the entire code.
• To run the R code line by line, Click Run icon to run the current line or selection of code. Or use key-binding ctrl + enter (windows) or cmd + enter (mac)

Environment Tab

• The (global) environment is where we are currently working.

• Anything created or imported into the current R/Python session is stored in the environment and shown in the Environment tab.

• After we run the R script, objects stored in the environment are

  • Data set mtcars
  • Object x storing integer values 1 to 10.
  • Object y storing three numeric values 3, 5, 9.

• Anything created or imported into the current R session is stored in our environment and shown in the Environment tab.
• We’ll talk about the R data type in detail later.

Python Script

• A Python script is a .py file that contains Python code.

• To create a Python script, go to File > New > Python Script, or click the green-plus icon on the topleft corner, and select Python Script.

Run Python Code

• Running Python code may need to update some packages. Please say YES!

• When you run the Python code in the R console, or type reticulate::repl_python(), the console will switch from R to Python.

• In the Python console >>> quit to switch back to the R console.

REPL = Read, Evaluate, Print, and Loop

or type reticulate::repl_python()

Environment Tab

• After we run the Python script, the object stored in the environment is
  • Object b storing a string Hello World!

• Anything created or imported into the current R session is stored in our environment and shown in the Environment tab.
• We’ll talk about the R data type in detail later.

History Tab

• The History tab keeps a record of all previous commands.
  • save icon: save all history to a file
  • To Console: send the selected commands to the console.
  • To Source: inserted the selected commands into the current script.

History Tab

• The History tab keeps a record of all previous commands.
  • save icon: save all history to a file
  • To Console: send the selected commands to the console.
  • To Source: inserted the selected commands into the current script.

In the console pane, use ⬆️ to show the previous commands.

R Packages 📦

• When we start a R session, only built-in packages like base, stats, graphics, etc are available.
• Installing packages is an easy way to get access to others data and functions.

and more!

• A language with many great add-on packages can become a very useful language.
• packages: which is a collection of functions and data for people to use.

Installing R Packages 📦

• To install a package, for example, the ggplot2 package, we use the command

install.packages("ggplot2")

• In the right-bottom pane, Packages > Install

Loading R Packages 📦

What happened when you run

ggplot(mpg, aes(x = displ, 
                y = hwy, 
                colour = class)) + 
    geom_point()

• To use any function or data in ggplot2, we write ggplot2:: followed by the name of the function or data.

ggplot2::ggplot(ggplot2::mpg, 
                ggplot2::aes(
                    x = displ, 
                    y = hwy, 
                    colour = class)
                ) + 
    ggplot2::geom_point()

• We can load the package into our R session using library().
• With library(ggplot2), R knows the function and data are from the ggplot2 package.

library(ggplot2)
ggplot(mpg, aes(x = displ, 
                y = hwy, 
                colour = class)) + 
    geom_point()

Help

• Don’t know how a function works or what a data set is about ❓
• 👉 Simply type ? followed by the data name or function name like

?mean
?mpg

What does the function mean() do? What is the size of mpg?

A document will show up in the Help tab, teaching you how to use the function or explaining the data set.

01-Running R Script

• Load R package ggplot2 into your Posit Cloud.

## install the package if you haven't!
________(ggplot2)

• Create a R script named lab01-run-script.R in your 3570-project.

• Copy and paste the code below into the script, and save it.

bar <- ggplot(data = diamonds) + 
    geom_bar(mapping = aes(x = cut, fill = cut), 
             show.legend = FALSE, width = 1) + 
    theme(aspect.ratio = 1) +
    labs(x = NULL, y = NULL)
bar + coord_flip()
bar + coord_polar()

• Source the script. A pretty plot showing up?!