In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning. Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "We can load the contents of the data.csv file into a data frame (the most intuitive structure to use with data in CSV format) by using the read.csv() function."
A block of code is set as follows:
data <- read.csv("./data_brexit_referendum.csv")
data[data$Leave == -1, "Leave"] <- NA
When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:
sum(is.na(data$Leave))
#> [1] 267
Any command-line input or output is written as follows:
$ sudo service mysql start
New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "Now that our code is ready, we should see a table appear in the Data Overview tab."