• Take some time to set up your screen
  • RStudio, Zoom window, Zoom chat, maybe a web browser
• Leave your camera on if you are comfortable
• Feel free to ask questions by:
  • Unmuting, raising hand, putting question in chat…
• Don’t hesitate to ask questions!

1. What is R and why should you learn it?
2. Finding your way around R/RStudio
3. Introduction to R
4. Break
5. Getting started with data

• text based (that’s a good thing!)
• code is great for reproducibility
• interdisciplinary and extensible
• works on data of all shapes and sizes
• produces high-quality graphics
• large and welcoming community
• free, open-source, and cross-platform

• R is a statistical programming language
• learning a programming language is much like learning any language
• we’re going to take our time, don’t be afraid to ask questions or ask Ryan to slow down
• once you are used to it, you can do things much more quickly
  • and, importantly, more reproducibly!

dir.create("data")
dir.create("data_output")
dir.create("fig_output")

Downloading the data

download.file("https://ndownloader.figshare.com/files/11492171",
              "data/SAFI_clean.csv", mode = "wb")

• using the pacakges tab in RStudio
• using the install.packages() function

Using all you’ve learned so far, make sure that you have the tidyverse package installed, and then install two more packages: here and lubridate

When you’re done, please give a :thumbs-up: or a :green-check: in the Zoom reactions.

What do you think is the current content of the object area_acres?

123.5 or 6.175?

Go to PollEv.com/ryanclement191 to respond!

Create two variables r_length and r_width and assign them values. It should be noted that, because length is a built-in R function, R Studio might add “()” after you type length and if you leave the parentheses you will get unexpected results. This is why you might see other programmers abbreviate common words. Create a third variable r_area and give it a value based on the current values of r_length and r_width. Show that changing the values of either r_length and r_width does not affect the value of r_area.

When you’re done, please give a :thumbs-up: or a :green-check: in the Zoom reactions.

Type in ?round at the console and then look at the output in the Help pane. What other functions exist that are similar to round? How do you use the digits parameter in the round function?

When you’re done, please give a :thumbs-up: or a :green-check: in the Zoom reactions.

We’ve seen that atomic vectors can be of type character, numeric (or double), integer, and logical. But what happens if we try to mix these types in a single vector?

What will happen in each of these examples? (hint: use class() to check the data type of your objects):

 num_char <- c(1, 2, 3, "a")
 num_logical <- c(1, 2, 3, TRUE)
 char_logical <- c("a", "b", "c", TRUE)
 tricky <- c(1, 2, 3, "4")

Why do you think this happens?

When you’re done, please give a :thumbs-up: or a :green-check: in the Zoom reactions.

You’ve probably noticed that objects of different types get converted into a single, shared type within a vector. In R, we call converting objects from one class into another class coercion. These conversions happen according to a hierarchy, whereby some types get preferentially coerced into other types. Can you draw a diagram that represents the hierarchy of how these data types are coerced?

When you’re done, please give a :thumbs-up: or a :green-check: in the Zoom reactions.

Using this vector of rooms, create a new vector with the NAs removed.

rooms <- c(1, 2, 1, 1, NA, 3, 1, 3, 2, 1, 1, 8, 3, 1, NA, 1)

When you’re done, please give a :thumbs-up: or a :green-check: in the Zoom reactions.

Use the function median() to calculate the median of the rooms vector.

Go to PollEv.com/ryanclement191 to respond!

Use R to figure out how many households in the set (rooms) use more than 2 rooms for sleeping.

Go to PollEv.com/ryanclement191 to respond!

R has a special data class, called factor, to deal with categorical data that you may encounter when creating plots or doing statistical analyses. Factors are very useful and actually contribute to making R particularly well suited to working with data. So we are going to spend a little time introducing them.

Factors represent categorical data. They are stored as integers associated with labels and they can be ordered (ordinal) or unordered (nominal). Factors create a structured relation between the different levels (values) of a categorical variable, such as days of the week or responses to a question in a survey. This can make it easier to see how one element relates to the other elements in a column. While factors look (and often behave) like character vectors, they are actually treated as integer vectors by R. So you need to be very careful when treating them as strings.

Once created, factors can only contain a pre-defined set of values, known as levels. By default, R always sorts levels in alphabetical order.

• Rename the levels of the factor to have the first letter in uppercase: “No”,”Undetermined”, and “Yes”.
• Now that we have renamed the factor level to “Undetermined”, can you recreate the barplot such that “Undetermined” is last (after “Yes”)?

When you’re done, please give a :thumbs-up: or a :green-check: in the Zoom reactions.

One of the most common issues that new (and experienced!) Rusers have is converting date and time information into a variable that is appropriate and usable during analyses. As a reminder, the best practice for dealing with date data is to ensure that each component of your date is stored as a separate variable. In our dataset, we have a column interview_date which contains information about the year, month, and day that the interview was conducted. Let’s convert those dates into three separate columns.

We are going to use the package lubridate, which is included in the tidyverse installation but not loaded by default, so we have to load it explicitly with library(lubridate).

To sign up for more sessions: go/summer-data-workshops/

Assessment survey: go/summer-data-assessment/

Ryan’s contact info: go/ryan/