In jr-packages/jrIntroduction: Jumping Rivers: Introduction to R

A suggestion

This is just a suggestion to try and help get you into "good habits" early. If I was sitting to take this practical now, I would start a new R script file. That way all of the work that you have done associated with today's course is in one place, and the code for each of the practicals is separate from one another. This might feel a bit tedious right now, but as the amount of code you write and number of projects you take part in increases it will pay off to have a structured workflow.

Tibbles

For this set of questions we will use the movies data from the IMDB database. Run the line of code below to load the data set into your R session.

data(movies, package = "jrIntroduction")

1. Use the head() function to inspect the top of the data, this can help give you a feel for what the data looks like and what variables are contained within the data r head(movies)

2. How many films and how many variables are in this data set? r dim(movies)

3. Recall that if I want to pull out a single column, or variable, from a data frame we can use $. To extract the titles from this data set we write movies$title.^[If you can't remember what the names of the columns are, you can use colnames(movies) to find out.] Using mean() and median() calculate these summary statistics for the film lengths r mean(movies$duration) median(movies$duration)

4. What year is the oldest film in the data set from? r min(movies$year)

5. How long is the longest film? r max(movies$duration)

6. What is the standard deviation of the film ratings? r sd(movies$rating)

7. Try running the following code r table(movies$action) What do you think is happening? r # Counting up the categories within a vector

Loading data from a CSV file

To give you some practice at reading in your own data, we're going to get you to read it in. The function

library("jrIntroduction")
get_csv_movies_file()

\noindent will copy a file called movies.csv into your current working directory. You can now import the data set using the Import Dataset button in RStudio, under the Environment tab

fname = system.file("import_data.png", package = "jrIntroduction")
knitr::include_graphics(fname)

\noindent This will generate R code that you can reuse.

Solutions

Solutions to the practical questions are contained within the package

vignette("solutions2", package = "jrIntroduction")

jr-packages/jrIntroduction documentation built on May 24, 2020, 5:19 p.m.