intro-to-R-tidyverse-cheatsheet.md

Intro to R and Tidyverse Cheatsheet

The tables below consist of valuable functions and commands that will help you through this module.

Each table represents a different library/tool and the corresponding commands.

Please note that these tables are not intended to tell you all the information you need to know about each command.

The hyperlinks found in each piece of code will take you to the documentation for further information on the usage of each command.

Base R

Read the Base R documentation here.

Library/Package	Piece of code	What it's called	What it does
Base R	library()	Library	Loads and attaches additional packages to the R environment.
Base R	<-	Assignment operator	Assigns a name to something in the R environment.
Base R	c()	Combine	Combines values into a vector or list.
Base R	%in%	"in" logical operator	Checks if the given value(s) on the left side of the operator are in the vector or other R object defined on the right side of the operator. It returns a logical TRUE or FALSE statement.
Base R	rm(x)	Remove	Removes object(s) x from your environment.
Base R	==, <=, >=, !=	Relational Operators	These are binary operators which allow for the comparison of values in an object.
Base R	str(x)	Object Structure	Gets a summary of the object x structure.
Base R	class(x)	Object Class	Returns the type of the values in object x.
Base R	nrow(x); ncol(x)	Number of Rows; Number of Columns	Get the number of rows and the number of columns in an object x, respectively.
Base R	length(x)	Number of Rows	Returns how long the object x is.
Base R	min(x)	Minimum	Returns the minimum value of all values in an object x.
Base R	sum(x)	Sum	Returns the sum of all values (values must be integer, numeric, or logical) in object x.
Base R	mean(x)	Mean	Returns the arithmetic mean of all values (values must be integer or numeric) in object x or logical vector x.
Base R	log(x)	Logarithm	Gives the natural logarithm of object x. log2(x) can be used to give the logarithm of the object in base 2. Or the base can be specified as an argument.
Base R	head()	Head	Returns the top 6 rows of an object in the environment by default. You can specify how many rows you want by including the n = argument.
Base R	tail()	Tail	Returns the bottom 6 rows of an object in the environment by default. You can specify how many rows you want by including the n = argument.
Base R	factor(x) or as.factor(x)	Factor	Coerces object x into a factor (which is used to represent categorical data). This function can be used to coerce object x into other data types, i.e., as.character, as.numeric, as.data.frame, as.matrix, etc.
Base R	levels(x)	Levels attributes	Returns or sets the value of the levels in an object x.
Base R	summary(x)	Object summary	Returns a summary of the values in object x.
Base R	data.frame()	Data Frame	Creates a data frame where the named arguments will be the same length.
Base R	sessionInfo()	Session Information	Returns the R version information, the OS, and the attached packages in the current R session.
Base R	file.path()	File path	Constructs the path to a desired file.
Base R	dir()	Directory	Lists the names of the files and/or directories in the named directory.
Base R	getwd()	Get working directory	Finds the current working directory.
Base R	setwd()	Set working directory	Changes the current working directory.
Base R	dir.exists()	Directory exists	Checks the file path to see if the directory exists there.
Base R	dir.create()	Create directory	Creates a directory at the specified file path.
Base R	apply()	Apply	Returns a vector or list of values after applying a specified function to values in each row/column of an object.
Base R	round()	Round	Rounds the values of an object to the specified number of decimal places (default is 0).
Base R	names()	Names	Gets or sets the names of an object.
Base R	colnames()	Column names	Gets or sets the column names of a matrix or data frame.
Base R	all.equal()	All equal	Checks if two R objects are nearly equal.
Base R	all()	All	Checks if all of the values are TRUE in a logical vector.
Base R	t()	Transpose	Returns the transpose of a matrix or data frame. If given a data frame, returns a matrix.

tidyverse

Read the tidyverse package documentation here.

dplyr

Read the dplyr package documentation here.
A vignette on the usage of the dplyr package can be found here.

Library/Package	Piece of code	What it's called	What it does
dplyr	%>%	Pipe operator	Funnels a data.frame through tidyverse operations
dplyr	filter()	Filter	Returns a subset of rows matching the conditions of the specified logical argument
dplyr	arrange()	Arrange	Reorders rows in ascending order. arrange(desc()) would reorder rows in descending order.
dplyr	select()	Select	Selects columns that match the specified argument
dplyr	mutate()	Mutate	Adds a new column that is a function of existing columns
dplyr	summarize()	Summarize	Summarizes multiple values in an object into a single value. This function can be used with other functions to retrieve a single output value for the grouped values. summarize and summarise are synonyms in this package. However, note that this function does not work in the same manner as the base R summary function.
dplyr	rename()	Rename	Renames designated columns while keeping all variables of the data.frame
dplyr	group_by()	Group By	Groups data into rows that contain the same specified value(s)
dplyr	inner_join()	Inner Join	Joins data from two data frames, retaining only the rows that are in both datasets.

ggplot2

Read the ggplot2 package documentation here.
A vignette on the usage of the ggplot2 package can be found here.

Library/Package	Piece of code	What it's called	What it does
ggplot2	ggplot()	GG Plot	Begins a plot that is finished by adding layers.
ggplot2	aes()	Aesthetic Mappings	Designates how variables in the data object are mapped to the visual properties of the ggplot.
ggplot2	geom_boxplot()	Boxplot	Creates a boxplot when added as a layer to a ggplot() object.
ggplot2	geom_density()	Density Plot	Creates a smoothed plot when added as a layer to a ggplot() object based on the computed density estimate.
ggplot2	geom_point()	Scatterplot	Creates a scatterplot when added as a layer to a ggplot() object.
ggplot2	geom_line()	Line plot	Creates a line plot when added as a layer to a ggplot() object by connecting the points in order of the x axis variable.
ggplot2	geom_hline()	Horizontal line	Annotates a plot with horizontal lines when added as a layer to a ggplot() object with one of the geom functions used to draw the plot, for example, geom_point().
ggplot2	theme_classic()	Classic Theme	Displays ggplot without gridlines. The ggtheme documentation has descriptions on additional themes that can be used.
ggplot2	xlab(); ylab(); ggtitle()	X Axis Labels; Y Axis Labels; GG Title	Modifies the labels on the x axis and on the y axis, and sets the title of a ggplot, respectively.
ggplot2	facet_wrap()	Facet Wrap	Plots individual graphs using specified variables to subset the data.
ggplot2	ggsave()	GG Save	Saves the last plot in working directory.
ggplot2	last_plot()	Last plot	Returns the last plot produced.

readr, tibble and tidyr

Read the readr package documentation here and the package vignette here.
Read the tibble package documentation here and the package vignette here. Read the tidyr package documentation here and the package vignette here.

Library/Package	Piece of code	What it's called	What it does
readr	read_tsv()	Read TSV	Reads in a TSV file from a specified file path. This function can be tailored to read in other common types of files. i.e. read_csv(), read_rds(), etc.
tibble	column_to_rownames()	Column to Rownames	Transforms an existing column called by a string into the rownames.
tibble	rownames_to_column()	Rownames to Column	Transforms the rownames of a data frame into a column (which is added to the start of the data frame). The string supplied as an argument will be the name of the new column.
tidyr	pivot_longer()	Pivot Longer	Lengthens a data frame by increasing the number of rows and decreasing the number of columns.