### Get help with Base R

#### Working with data types

Topic Description
as.character() Coerce (“change”) a value to be character type
as.factor() Coerce (“change”) a value to be factor type
as.numeric() Coerce (“change”) a value to be character type
class() Determine a value’s type

#### Working with R libraries/packages

Function Description
library() Load a library/package into an R session
install.packages() Install a library/package for the first time

#### Working with files and directories

Function Description
getwd() Ask R what your R session’s working directory is
setwd() Change the current R session’s working directory
dir.exists() Ask if a given directory (folder) exists on your computer
file.exists() Ask if a given file exists on your computer
file.path() Construct a path to a given file or directory (folder)

#### Working with numbers

Function Description
log() Calculate the natural log (or other specified base) of a number or array of numbers
sqrt() Calculate the square root of a number or array of numbers
abs() Calculate the absolute value of a number or array of numbers
round() Round a number or array of numbers to a specified number of decimal places
ceiling() Round a number or array of numbers up to the next highest integer
floor() Round a number or array of numbers down to the next lowest integer

#### Working with arrays, strings, and more

Function Description
c() Create new arrays
length() Determine the length of an array (not of a single string)
nchar() Determine the number of characters in a string
levels() Determine the levels (i.e., ordered categories) of a factor variable
unique() Remove duplicates from an array, i.e. keep only unique values
paste() and paste0() Combine several strings into one
ifelse() Assign a value based on whether a statement is TRUE or FALSE
cat() and print Functions you can use to explicitly print
all() Asks, “do ALL values in an array meet a logical condition?”
any() Asks, “do ANY (at least one) values in an array meet a logical condition?”

#### Working with data frames (and other objects)

Function Description
data.frame() Create a new data frame from scratch
nrow() Determine the number of rows in a tibble (data frame)
ncol() Determine the number of columns in a tibble (data frame)
names() Determine the column names of a tibble (data frame)
head() See the first 6 rows of a tibble (data frame)
tail() See the last 6 rows of a tibble (data frame)
summary() See a summary of columns in tibble (data frame)
str() See the structure of a tibble (data frame)

#### Summary statistics

Function Description
mean() Calculate the average of an array of numbers
median() Calculate the median of an array of numbers
max() Calculate the maximum value of an array of numbers
min() Calculate the minimum value of an array of numbers
sd() Calculate the standard deviation of an array of numbers
sum() Calculate the sum of an array of numbers
summary() Calculate several summary statistics for an array of numbers
table() Count the occurrences of each value in an array of any type

### Get help with ggplot2

#### Fundamental ggplot2

Function Description
aes() Provide a ggplot2 with aesthetic mappings from dataset columns
ggplot() Tell ggplot2 which dataset to plot and establish a ggplot2 canvas
ggsave() Save a plot made with ggplot2 to a file

#### Geoms

Function Description
geom_boxplot() Create boxplots
geom_density() Create density plots
geom_histogram() Create histograms
geom_jitter() Create jitter (strip) plots
geom_point() Create point shapes, often (but not always) to create scatterplots
geom_smooth() Add a trendline to a plot, often (but not always) to a scatterplot
geom_col() Create bar plots whose height corresponds to literal values in the data
geom_bar() Create bar plots whose height corresponds to counted number of observations of a categorical variable
geom_text() and geom_label() Create labels in plots
geom_segment() Add line segments to plots

#### Axes, labels, and faceting

Function or tutorial Description
Axes tutorial Customizing x- and y- axes
xlim() Change x-axis limits
ylim() Change y-axis limits
labs() Customize plot labels, including axes, titles, and legends
facet_wrap() Create a faceted (paneled) plot across 1 variable
facet_grid() Create a faceted (paneled) grid of plots across 2 variables

#### Color and fill scales

Function or tutorial Description
Color and fill scales tutorial Customizing color and fill scales
scale_color_manual() Specify custom color scale mappings for discrete data
scale_fill_manual() Specify custom fill scale mappings for discrete data
scale_color_gradient() Specify custom color gradient scale mappings for continuous data
scale_fill_gradient() Specify custom fill gradient scale mappings for continuous data
scale_color_gradient2() Specify custom two-way color gradient scale mappings for continuous data
scale_fill_gradient2() Specify custom two-way fill gradient scale mappings for continuous data
scale_color_brewer() Specify colorbrewer color scale mappings for discrete data
scale_fill_brewer() Specify colorbrewer fill scale mappings for discrete data
scale_color_distiller() Specify colorbrewer color scale mappings for continuous data
scale_fill_distiller() Specify colorbrewer fill scale mappings for continuous data
scale_color_viridis_d() Specify viridis color scale mappings for discrete data
scale_fill_viridis_d() Specify viridis fill scale mappings for discrete data
scale_color_viridis_c() Specify viridis color scale mappings for continuous data
scale_fill_viridis_c() Specify viridis fill scale mappings for continuous data

#### Other scales

scale_shape_manual() Specify custom shape mappings
scale_size_manual() Specify custom size mappings
scale_alpha_manual() Specify custom alpha (transparency) mappings
scale_linetype_manual() Specify custom linetype mappings

#### Themes

Function Description
theme() and associated tutoral Customizing themes
theme_set() Set the default theme
theme_gray() Specify the built-in “gray” (default) theme
theme_grey() Specify the built-in “grey” (default) theme
theme_bw() Specify the built-in “bw” theme
theme_linedraw() Specify the built-in “linedraw” theme
theme_light() Specify the built-in “light” theme
theme_dark() Specify the built-in “dark” theme
theme_minimal() Specify the built-in “minimal” theme
theme_classic() Specify the “classic” theme
theme_void() Specify the built-in “void” theme

### Get help with dplyr

#### One-table verbs

Function Description
arrange() Arrange tibble (data frame) rows
distinct() Remove duplicate rows from a tibble (data frame)
mutate() Create new or modify existing columns in a tibble (data frame)
filter() Keep only certain rows from a tibble (data frame) based on TRUE or FALSE
select() Keep, remove, or reorder columns in a tibble (data frame)
rename() Rename existing columns in a tibble (data frame)
glimpse() See an overview of tibble (data frame) contents
pull() Extract out a column from a tibble (data frame) into its own array
slice() Keep only certain rows from a tibble (data frame) based on index
group_by() Establish a grouping in a tibble (data frame)
ungroup() Undo any groupings in a tibble (data frame)
summarize() Summarize values in a tibble (data frame) to produce a smaller summarized tibble
tally() Count the number of rows in each grouping of a tibble (data frame)
count() Simultaneously group and count the number of rows in each grouping of a tibble (data frame)

#### Two-table verbs

Function Description
bind_cols() Combine arrays or tibbles (data frames) by columns
bind_rows() Combine arrays or tibbles (data frames) by rows
left_join() Merge two relational tibbles (data frames) based on the left side
right_join() Merge two relational tibbles (data frames) based on the right side
full_join() Merge two relational tibbles (data frames) fully
inner_join() Merge two relational tibbles (data frames) based on what they have in common
anti_join() Merge relational tibbles (data frames) based on what they do not have in common

#### Helper functions

Function Description
if_else() Assign a value based on whether a statement is TRUE or FALSE , ensuring same type
case_when() Assign a value based on a series of conditions are TRUE or FALSE
n() Returns the number of rows in a tibble group

### Get help with tidyselect helpers

Function Description
everything() Select all columns, except those already explicitly stated
contains() Select all columns that contain a given string argument
starts_with() Select all columns that start with a given string, i.e. prefix
ends_with() Select all columns that end with a given string, i.e. suffix
last_col() Select the last column
matches() Select all columns that match a regular expression (a special type of pattern-matching string)

### Get help with forcats

Function Description
fct_relevel() Reorder levels in a factor to a custom order
fct_infreq() Reorder levels factor in a factor based on frequency
fct_rev() Reverse the order of levels in a factor
fct_reorder() Reorder levels in a factor based on values of another variable
fct_lump_n() Combine infrequently occurring levels of a factor into one
fct_lump_min() Combine infrequently occurring levels of a factor into one
fct_lump_prop() Combine infrequently occurring levels of a factor into one

### Get help with readr

Function Description
read_csv() Read a CSV file into R
read_tsv() Read a TSV file into R
read_csv2() Read a CSV2 file into R
read_delim() Read a delimited file of any kind into R
write_csv() Write (save) a tibble (data frame) to a CSV file
write_tsv() Write (save) a tibble (data frame) to a TSV file
write_csv2() Write (save) a tibble (data frame) to a CSV2 file
write_delim() Write (save) a tibble (data frame) to a delimited file

### Get help with tibble

Function Description
as_tibble() Coerce a variable (often a data frame) into a tibble
tibble() Create a new tibble from scratch
tribble() Create a new tibble from scratch

### Get help with tidyr

Function Description
pivot_longer() Make a tibble (data frame) longer
pivot_wider() Make a tibble (data frame) wider
drop_na() Remove rows containing NA values from a tibble (data frame)
unite() Unite (combine) two columns in a tibble (data frame) into a single column
separate() Separate a single column in a tibble (data frame) into two new columns

### Get help with stringr

Function Description
str_count() Count the number of occurrences of a substring or regular expression in a string
str_replace() Replace the first occurrence of a substring or regular expression in a string with a given replacement string
str_replace_all() Replace all occurrences of a substring or regular expression in a string with a given replacement string
str_detect() Determine whether it is TRUE or FALSE that a given string contains a substring
str_starts() Determine whether it is TRUE or FALSE that a given string starts with a given substring
str_ends() Determine whether it is TRUE or FALSE that a given string ends with a given substring

### Get help with glue

Function Description
glue() Quickly combine strings and variables into a single string