R Cheat Sheet

How to get help

From the console:

Type ?function_name to see that function's Help page. Type ??search_term to find all the functions in R (that you have downloaded) that contain your search term.

On the internet:

• Rseek
• Bioconductor mailing list
• Use the tag “[r]” on StackOverflow.

How to stop

q()  # exit R
# Use the escape key to kill a command

Inspect an object

Note: Not all of these commands will work on every type of object.

str(x)
head(x)
tail(x)
dim(x)
length(x)
nrow(x)
ncol(x)
attr(x)
class(x)
typeof(x)
mode(x)
plot(x)
hist(x)
boxplot(x)
hist(x)
summary(x)
unique(x)
colnames(x)
rownames(x)
length(x)
dput(x)

Understanding your working environment

ls()  # List all objects
search()  # List all attached packages
getwd()  # get the path of the current working directory
sessionInfo()  # summary of your system and R session, post this info when
# asking for help on mailing lists and online forums

Data types

Diagram by Jenny Bryan.

Data structures

R has multiple native data structures. The table below shows an overview that demonstrates how to choose which data structure to choose based on the number of dimensions of the data and whether it is all the same type of data (homogeneous) or multiple types (heterogenous).

Table inspired by Hadley Wickham's chapter on data structures.