In dtkaplan/checkr: Facilities for checking R submissions in tutorials

library(learnr)
library(checkr)
knitr::opts_chunk$set(echo = FALSE)
tutorial_options(exercise.checker = checkr::check_for_learnr)
source(system.file("learnr_examples/internal-examples.R", 
                          package = "checkr"))

Problem 1

Fill in the blanks in the following code to create a ggplot2 command that will produce the following scatter plot with the mtcars data.
```r library(ggplot2) ggplot(mtcars, aes(x = mpg, y = hp, color = cyl)) + geom_point()

>
> There are four blanks. You'll have to replace all of them with the correct contents to generate the plot.

```r
library(ggplot2)
ggplot(mtcars, aes(x = ____, y = ____, color = ____)) +
  ____()

To check the submission, we need to create a pattern that will let us look up the student's values for each of the blanks, then compare these to the correct answer. The check_blanks() function takes, as its second argument, an expression with the blanks. Since there are multiple blanks, each has been given a name for later reference.

check_exer_14(USER_CODE)

Problem 2

Calculate the hypothenuse length C of a right triangle whose other edges are A and B.

A <- 3
B <- 4
C <- ........(A^2 + B^2)

check_pythag(USER_CODE)

Try some different submissions.

• C <- sqrt(A^2 + B^2)
• C <- log(A^2 + B^2)
• C <- ........(A^2 + B^2) that is, the dots were not replaced
• C <- sqrt(A + B)

dtkaplan/checkr documentation built on May 15, 2019, 4:59 p.m.