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Introduction 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. Please be aware that the documentation will generally provide information about the given function's most current version (or a recent version, depending on how often the documentation site is updated). This will usually (but not always!) match what you have installed on your machine. If you have a different version of R or other R packages, the documentation may differ from what you have installed.

Table of Contents

Base R

Read the Base R documentation.

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 [` >`](https://rdrr.io/r/base/pipeOp.html) Pipe operator
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. This resource also provides a helpful explanation about its usage.
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) Length 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(); tail() Head; Tail Returns the top 6 (head()) or bottom 6 (tail()) 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 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, as well as the philosophy behind the tidyverse.

dplyr

Read the dplyr package documentation, and a vignette on its usage.

Library/Package Piece of code What it's called What it does
dplyr/magrittr %>% Pipe operator Funnels an object from the output of one function to input of the next function (used like the base pipe `
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, an overall reference for ggplot2 functions, and a vignette on the usage of the ggplot2 aesthetics. Additional vignettes are available from the "Articles" dropdown menu on this webpage.

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 a horizontal line when added as a layer to a ggplot() object
ggplot2 geom_vline() Vertical line Annotates a plot with a vertical line when added as a layer to a ggplot() object
ggplot2 theme_classic() Classic Theme Displays ggplot without gridlines. The ggtheme documentation has descriptions on additional themes that can be used.
ggplot2 labs() Labels Modify labels (axis, title, legends) on a ggplot() object.
ggplot2 xlab(); ylab(); ggtitle() X Axis Labels; Y Axis Labels; GG Title Alternative individual functions to add individual plot labels: x-axis, y-axis, and title, 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, fs, tibble tidyr

Read the readr package documentation and a vignette on its usage. Read the fs package documentation. Read the tibble package documentation and a vignette on its usage. Read the tidyr package documentation and a vignette on its usage.

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, e.g. read_csv(), read_rds(), etc.
fs dir_create() Create directory Create a directory, unless the directory already exists.
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.