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@@ -9,23 +9,22 @@ Here are our current offerings, organized by level of difficulty: | |
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#### Beginner | ||
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- R Programming | ||
- Data Analysis | ||
- Mathematical Biostatistics Boot Camp | ||
- Open Intro | ||
- **R Programming**: The basics of programming in R | ||
- **R Programming Alt**: Same as the original, but modified slightly for in-class use | ||
- **Data Analysis**: Basic ideas in statistics and data visualization | ||
- **Mathematical Biostatistics Boot Camp**: One- and two-sample t-tests, power, and sample size | ||
- **Open Intro**: A very basic introduction to statistics, data analysis, and data visualization | ||
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#### Intermediate | ||
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- Regression Models | ||
- **Regression Models**: The basics of regression modeling in R | ||
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#### Advanced | ||
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- *Coming soon!* | ||
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Since our users come from a variety backgrounds, it's very hard to label material as **Beginner**, **Intermediate**, or **Advanced**. If you find something that is labelled **Beginner** to be challenging, please don't be discouraged. The first step of learning anything is to acknowledge that you are capable of understanding it. True understanding will come with time and practice. | ||
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*** | ||
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## Install and run a course automatically from swirl | ||
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**This is the preferred method of installing courses.** It automates the process by allowing you to do everything right from the R console. | ||
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If that doesn't work for you... | ||
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*** | ||
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## Install and run a course manually | ||
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If the automatic course installation method outlined above does not work for you, then there's a simple alternative. | ||
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install_course_zip("~/Downloads/swirl_courses-master.zip", multi=TRUE) | ||
``` | ||
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## Uninstall a course | ||
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If you'd like to remove a course at any time, you can use `uninstall_course("Course Name Here")`. | ||
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## Using swirl in the classroom | ||
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Instructors around the world are using swirl in their classrooms. We think this is awesome. If you're an instructor, please feel free to do the same -- free of charge. While your students may be paying to take your course or attend your institution, we simply ask that you don't charge people *directly* for the use of our software or instructional content. | ||
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If you are not sure about a particular use case, don't hesitate to send us an email at [email protected]. |
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notify <- function() { | ||
e <- get("e", parent.frame()) | ||
if(e$val == "No") return(TRUE) | ||
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good <- FALSE | ||
while(!good) { | ||
# Get info | ||
name <- readline_clean("What is your full name? ") | ||
address <- readline_clean("What is the email address of the person you'd like to notify? ") | ||
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# Repeat back to them | ||
message("\nDoes everything look good?\n") | ||
message("Your name: ", name, "\n", "Send to: ", address) | ||
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yn <- select.list(c("Yes", "No"), graphics = FALSE) | ||
if(yn == "Yes") good <- TRUE | ||
} | ||
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# Get course and lesson names | ||
course_name <- attr(e$les, "course_name") | ||
lesson_name <- attr(e$les, "lesson_name") | ||
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subject <- paste(name, "just completed", course_name, "-", lesson_name) | ||
body = "" | ||
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# Send email | ||
swirl:::email(address, subject, body) | ||
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hrule() | ||
message("I just tried to create a new email with the following info:\n") | ||
message("To: ", address) | ||
message("Subject: ", subject) | ||
message("Body: <empty>") | ||
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message("\nIf it didn't work, you can send the same email manually.") | ||
hrule() | ||
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# Return TRUE to satisfy swirl and return to course menu | ||
TRUE | ||
} | ||
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readline_clean <- function(prompt = "") { | ||
wrapped <- strwrap(prompt, width = getOption("width") - 2) | ||
mes <- stringr::str_c("| ", wrapped, collapse = "\n") | ||
message(mes) | ||
readline() | ||
} | ||
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hrule <- function() { | ||
message("\n", paste0(rep("#", getOption("width") - 2), collapse = ""), "\n") | ||
} |
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- Class: meta | ||
Course: R Programming | ||
Lesson: Basic Building Blocks | ||
Author: Nick Carchedi | ||
Type: Standard | ||
Organization: JHU Biostat | ||
Version: 2.2.0 | ||
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- Class: text | ||
Output: In this lesson, we will explore some basic building blocks of the R programming | ||
language. | ||
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- Class: text | ||
Output: If at any point you'd like more information on a particular topic related | ||
to R, you can type help.start() at the prompt, which will open a menu of resources | ||
(either within RStudio or your default web browser, depending on your setup). | ||
Alternatively, a simple web search often yields the answer you're looking for. | ||
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- Class: cmd_question | ||
Output: In its simplest form, R can be used as an interactive calculator. Type | ||
5 + 7 and press Enter. | ||
CorrectAnswer: 5 + 7 | ||
AnswerTests: omnitest(correctExpr='5 + 7') | ||
Hint: Type 5 + 7 and press Enter. | ||
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- Class: text | ||
Output: R simply prints the result of 12 by default. However, R is a programming | ||
language and often the reason we use a programming language as opposed to a calculator | ||
is to automate some process or avoid unnecessary repetition. | ||
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- Class: text | ||
Output: In this case, we may want to use our result from above in a second calculation. | ||
Instead of retyping 5 + 7 every time we need it, we can just create a new variable | ||
that stores the result. | ||
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- Class: text | ||
Output: 'The way you assign a value to a variable in R is by using the assignment | ||
operator, which is just a ''less than'' symbol followed by a ''minus'' sign. It | ||
looks like this: <-' | ||
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- Class: text | ||
Output: Think of the assignment operator as an arrow. You are assigning the value | ||
on the right side of the arrow to the variable name on the left side of the arrow. | ||
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- Class: cmd_question | ||
Output: To assign the result of 5 + 7 to a new variable called x, you type x <- | ||
5 + 7. This can be read as 'x gets 5 plus 7'. Give it a try now. | ||
CorrectAnswer: x <- 5 + 7 | ||
AnswerTests: any_of_exprs('x <- 5 + 7', 'x <- 7 + 5') | ||
Hint: Type x <- 5 + 7. It's important to include a single space on each side of | ||
the assignment operator, but do NOT put a space between the `<` and the `-` that | ||
form the arrow. | ||
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- Class: text | ||
Output: You'll notice that R did not print the result of 12 this time. When you | ||
use the assignment operator, R assumes that you don't want to see the result immediately, | ||
but rather that you intend to use the result for something else later on. | ||
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- Class: cmd_question | ||
Output: To view the contents of the variable x, just type x and press Enter. Try | ||
it now. | ||
CorrectAnswer: x | ||
AnswerTests: omnitest(correctExpr='x') | ||
Hint: Type x and press Enter. This will automatically print the value of x. | ||
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- Class: cmd_question | ||
Output: Now, store the result of x - 3 in a new variable called y. | ||
CorrectAnswer: y <- x - 3 | ||
AnswerTests: omnitest(correctExpr='y <- x - 3') | ||
Hint: Type y <- x - 3 and press Enter. Whether you use x - 3 or x-3 is personal | ||
preference, but it's good habit to include a space on either side of the assignment | ||
operator. | ||
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- Class: cmd_question | ||
Output: What is the value of y? Type y to find out. | ||
CorrectAnswer: 'y' | ||
AnswerTests: omnitest(correctExpr='y') | ||
Hint: Type y and press Enter. | ||
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- Class: text | ||
Output: Now, let's create a small collection of numbers called a vector. Any object | ||
that contains data is called a data structure and numeric vectors are the simplest | ||
type of data structure in R. In fact, even a single number is considered a vector | ||
of length one. | ||
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- Class: cmd_question | ||
Output: The easiest way to create a vector is with the c() function, which stands | ||
for 'concatenate' or 'combine'. To create a vector containing the numbers 1.1, | ||
9, and 3.14, type c(1.1, 9, 3.14). Try it now and store the result in a variable | ||
called z. | ||
CorrectAnswer: z <- c(1.1, 9, 3.14) | ||
AnswerTests: omnitest(correctExpr='z <- c(1.1, 9, 3.14)') | ||
Hint: Inputting z <- c(1.1, 9, 3.14) will assign the vector (1.1, 9, 3.14) to a | ||
new variable called z. Including single spaces after the commas in the vector | ||
is not required, but helps make your code less cluttered and more readable. | ||
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- Class: cmd_question | ||
Output: Anytime you have questions about a particular function, you can access R's | ||
built-in help files via the `?` command. For example, if you want more information | ||
on the c() function, type ?c without the parentheses that normally follow a function | ||
name. Give it a try. | ||
CorrectAnswer: ?c | ||
AnswerTests: omnitest(correctExpr='?c') | ||
Hint: Type ?c and press Enter. This will bring up the help file for the c() function. | ||
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- Class: cmd_question | ||
Output: Type z to view its contents. Notice that there are no commas separating | ||
the values in the output. | ||
CorrectAnswer: z | ||
AnswerTests: omnitest(correctExpr='z') | ||
Hint: Type z and press Enter to view its contents. | ||
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- Class: cmd_question | ||
Output: You can combine vectors to make a new vector. Create a new vector that contains | ||
z, 555, then z again in that order. Don't assign this vector to a new variable, | ||
so that we can just see the result immediately. | ||
CorrectAnswer: c(z, 555, z) | ||
AnswerTests: omnitest(correctExpr='c(z, 555, z)') | ||
Hint: Type c(z, 555, z). Don't create a new variable. We just want to view the result. | ||
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- Class: cmd_question | ||
Output: 'Numeric vectors can be used in arithmetic expressions. Type the following | ||
to see what happens: z * 2 + 100.' | ||
CorrectAnswer: z * 2 + 100 | ||
AnswerTests: omnitest(correctExpr='z * 2 + 100') | ||
Hint: Enter z * 2 + 100, without assigning the result to a variable. The `*` symbol | ||
is used for multiplication and shares a key with the number 8 on many keyboards. | ||
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- Class: text | ||
Output: First, R multiplied each of the three elements in z by 2. Then it added | ||
100 to each element to get the result you see above. | ||
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- Class: text | ||
Output: Other common arithmetic operators are `+`, `-`, `/`, and `^` (where x^2 | ||
means 'x squared'). To take the square root, use the sqrt() function and to take | ||
the absolute value, use the abs() function. | ||
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- Class: cmd_question | ||
Output: Take the square root of z - 1 and assign it to a new variable called my_sqrt. | ||
CorrectAnswer: my_sqrt <- sqrt(z - 1) | ||
AnswerTests: omnitest(correctExpr='my_sqrt <- sqrt(z - 1)') | ||
Hint: Assign the result of sqrt(z - 1) to a variable called my_sqrt. | ||
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- Class: mult_question | ||
Output: Before we view the contents of the my_sqrt variable, what do you think it | ||
contains? | ||
CorrectAnswer: a vector of length 3 | ||
AnswerChoices: a vector of length 3; a single number (i.e a vector of length 1); | ||
a vector of length 0 (i.e. an empty vector) | ||
AnswerTests: omnitest(correctVal='a vector of length 3') | ||
Hint: 'Think about how R handled the other ''vectorized'' operations: element-by-element.' | ||
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- Class: cmd_question | ||
Output: Print the contents of my_sqrt. | ||
CorrectAnswer: my_sqrt | ||
AnswerTests: omnitest(correctExpr='my_sqrt') | ||
Hint: Just type my_sqrt and press Enter to view its value. | ||
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- Class: text | ||
Output: As you may have guessed, R first subtracted 1 from each element of z, then | ||
took the square root of each element. This leaves you with a vector of the same | ||
length as the original vector z. | ||
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- Class: cmd_question | ||
Output: Now, create a new variable called my_div that gets the value of z divided | ||
by my_sqrt. | ||
CorrectAnswer: my_div <- z / my_sqrt | ||
AnswerTests: omnitest(correctExpr='my_div <- z / my_sqrt') | ||
Hint: Enter my_div <- z / my_sqrt. The spaces on either side of the `/` sign are not | ||
required, but can often improve readability by making code appear less cluttered. | ||
In the end, it's personal preference. | ||
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- Class: mult_question | ||
Output: Which statement do you think is true? | ||
CorrectAnswer: The first element of my_div is equal to the first element of z divided | ||
by the first element of my_sqrt, and so on... | ||
AnswerChoices: The first element of my_div is equal to the first element of z divided | ||
by the first element of my_sqrt, and so on...; my_div is a single number (i.e a | ||
vector of length 1); my_div is undefined | ||
AnswerTests: omnitest(correctVal='The first element of my_div is equal to the first | ||
element of z divided by the first element of my_sqrt, and so on...') | ||
Hint: Think about how R handled the other 'vectorized' operations like `+` and `*`. | ||
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- Class: cmd_question | ||
Output: Go ahead and print the contents of my_div. | ||
CorrectAnswer: my_div | ||
AnswerTests: omnitest(correctExpr='my_div') | ||
Hint: Type my_div and press Enter to see its contents. | ||
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- Class: text | ||
Output: When given two vectors of the same length, R simply performs the specified | ||
arithmetic operation (`+`, `-`, `*`, etc.) element-by-element. If the vectors | ||
are of different lengths, R 'recycles' the shorter vector until it is the same | ||
length as the longer vector. | ||
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- Class: text | ||
Output: When we did z * 2 + 100 in our earlier example, z was a vector of length | ||
3, but technically 2 and 100 are each vectors of length 1. | ||
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- Class: text | ||
Output: 'Behind the scenes, R is ''recycling'' the 2 to make a vector of 2s and | ||
the 100 to make a vector of 100s. In other words, when you ask R to compute z | ||
* 2 + 100, what it really computes is this: z * c(2, 2, 2) + c(100, 100, 100).' | ||
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- Class: cmd_question | ||
Output: To see another example of how this vector 'recycling' works, try adding | ||
c(1, 2, 3, 4) and c(0, 10). Don't worry about saving the result in a new variable. | ||
CorrectAnswer: c(1, 2, 3, 4) + c(0, 10) | ||
AnswerTests: omnitest(correctExpr='c(1, 2, 3, 4) + c(0, 10)') | ||
Hint: Enter c(1, 2, 3, 4) + c(0, 10) in the console to see how R adds two vectors | ||
of different length. Don't assign the result to a variable. | ||
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- Class: text | ||
Output: If the length of the shorter vector does not divide evenly into the length | ||
of the longer vector, R will still apply the 'recycling' method, but will throw | ||
a warning to let you know something fishy might be going on. | ||
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- Class: cmd_question | ||
Output: Try c(1, 2, 3, 4) + c(0, 10, 100) for an example. | ||
CorrectAnswer: c(1, 2, 3, 4) + c(0, 10, 100) | ||
AnswerTests: omnitest(correctExpr='c(1, 2, 3, 4) + c(0, 10, 100)') | ||
Hint: Type c(1, 2, 3, 4) + c(0, 10, 100) to see how R handles adding two vectors, | ||
when the shorter vector's length does not divide evenly into the longer vector's | ||
length. Don't worry about assigning the result to a variable. | ||
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- Class: text | ||
Output: Before concluding this lesson, I'd like to show you a couple of time-saving tricks. | ||
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- Class: text | ||
Output: Earlier in the lesson, you computed z * 2 + 100. Let's pretend that you made a mistake and that you meant to add 1000 instead of 100. You could either re-type the expression, or... | ||
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- Class: cmd_question | ||
Output: In many programming environments, the up arrow will cycle through previous commands. Try hitting the up arrow on your keyboard until you get to this command (z * 2 + 100), then change 100 to 1000 and hit Enter. If the up arrow doesn't work for you, just type the corrected command. | ||
CorrectAnswer: z * 2 + 1000 | ||
AnswerTests: omnitest(correctExpr='z * 2 + 1000') | ||
Hint: If your environment does not support the up arrow feature, then just type the corrected command to move on. | ||
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- Class: text | ||
Output: Finally, let's pretend you'd like to view the contents of a variable that you created earlier, but you can't seem to remember if you named it my_div or myDiv. You could try both and see what works, or... | ||
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- Class: cmd_question | ||
Output: You can type the first two letters of the variable name, then hit the Tab key (possibly more than once). Most programming environments will provide a list of variables that you've created that begin with 'my'. This is called auto-completion and can be quite handy when you have many variables in your workspace. Give it a try. (If auto-completion doesn't work for you, just type my_div and press Enter.) | ||
CorrectAnswer: my_div | ||
AnswerTests: omnitest(correctExpr='my_div') | ||
Hint: If your programming environment doesn't support auto-completion, just type my_div and hit Enter to move on. | ||
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- Class: mult_question | ||
Output: Would you like to inform someone about your successful completion of this lesson? | ||
CorrectAnswer: NULL | ||
AnswerChoices: Yes; No | ||
AnswerTests: notify() | ||
Hint: NULL |
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