Glossary of R Functions
Ben Kite, Paul Johnson
05/17/2018

CrossTable(): In gmodels package, an SPSS-style cross-tabulation
abline(): Add stright line to a plot, many interfaces allowed
abline(): Generate a straight line that spans the plot
addmargins(): Add marginal sum to a table
aes(): In ggplot2, general design of a plot
anova(): Compare 2 models, by Chi-square or F test
apply(): For matrix input, calculate a value for each row or column
as.factor(): Coerce a variable into a factor
as.vector(): Coerce an object into a vector
attributes(): Ask object for its secrets (class and other "hidden")
barplot(): Creates a barplot from a table
boxplot(): Create a box plot
bquote(): In plotmath, used to combine expression with calculations
bquote(): a way to combine text strings and output into an R expression (see plotmath)
by(): Run a function for each section of rows (by a categorical var)
c(): Concatenate (or column vector)
cat(): write an object to screen into file, without beautification
class(): Ask an object for its class. Same as checking attributes()
coef(): Coefficient extractor, behaves differently for object classes
colnames(): Vector of column names from a data.frame
combineLevels(): rockchalk package to combine levels in a factor
compareCFA(): In kutils, create a table for difference tests
confint(): Confidence intervals from an object
data.frame(): Create a data frame
dev.new(): Create a new on-screen table.
dir.create(): Create a directory
dir.exists(): Check if directory exists in the OS
dlogis(): density of a logistic distribution
eval(): calculates the value of a call object (unevaluated expression)
exp(): exponential values in the input, as in exp(x)
expression(): Treat argument as an R expression, not as char string
factor(): Creates a factor variable
file.copy(): Copy files or directories
file.exists(): Returns true if a file exists
fitted(): Ask a regression model for the predicted values
for(): Used to create loops
frac(): Used in plotmath to create fractions
function(): Creates functions
genTable(): In memisc, create cross tabulation
ggplot(): In ggplot2, this creates a device
gray.colors(): Creates a simple color palate of gray
grid(): Adds a rectangular display on a plot
gsub(): Substitutes characters using GNU regular expressions
head(): Show first elements of an object
hexbin(): Package to create hexagonal "heat map"
hexbinplot(): Renders the hex plot
hist(): Generate a Histogram
if(): An if logical operator
ifelse(): Used for recoding. If input 1 is TRUE, item 2; else 3.
influence.measures(): In regression, identify outliers
invisible(): Returns a value, but does not run print() on it.
jitter(): In plotting, adds small noise to x,y coordinates
latex(): Hmisc function for latex markup
legend(): Add a legend to a plot
length(): Check the number of items in a vector
levels(): Ask a factor for its current levels
leveneTest(): In car, test for homogeneous variance
library(): Interact with the package collection
lines(): add lines to a plot
list(): Create an R list object
lm(): Linear model: regression
load(): Import an RData workspace (collection of objects)
log(): logarithm, defaults to natural log
ls(): list items in workspace
max(): maximum, don't forget na.rm=TRUE
mean(): Find the mean
meanCenter(): In rockchalk, replace predictors with mean-centered equivalents
median(): median, don't forget na.rm=TRUE
min(): minimum, don't forget na.rm=TRUE
model.frame(): Create a data frame necessary to re-estimate a regression model
model.matrix(): Extract the design matrix from a regression model
mtext(): write margin text into a plot
names(): Retrieve the names of items in a list
newdata(): In rockchalk, creates a new data.frame suitable for use with predict
options(): See or set values of the user session, such as number of digits displayed in output.
pairs(): Create a scatterplot matrix
par(): Set or query graphical parameters
parameterEstimates(): In lavaan, summarize a fitted model
parse(): Interpret an expression to create a call (executable statement)
paste(): Combine character values into a longer string. Is vectorized, works with vectors paste(x, y). 
paste0(): Combine character strings, but with no space between items
pctable(): In rockchalk, create a column-percentage table
pdf(): Create output file "device" that subsequent plot commands will draw into
pdf.options(): Used in beginning of script to set defaults
percent(): In memisc, can help in creating column percents
phantom(): In plotmath, inserts small blank space
plot(): Generate a plot
plotSlopes(): In rockchalk, plot a regression with interactions
points(): Add points to a plot
predict(): R generic for calculating fitted values in regression models
predictOMatic(): In rockchalk, convenience to create newdata and predictions
prop.table(): Creates proportions in a cross tabulation
quantile(): Calculate quantiles values (data separator points)
range(): a vector with min and max
rbinom(): Simulate values from a binomial distribution
read.table(): Read a data frame from a text file
readRDS(): Read an R serialization file
rect(): Draw a rectangle on a plot
require(): Loads a package, almost same as library()
resid(): Ask a regression for the residuals
rgamma(): Simulate values from a gamma distribution
ribbon(): In ggplot2, used to draw a shaded area
rnorm(): Generate a normal distribution with mean 0 and variance 1
round(): Rounds floating points to integers
rowMeans(): For a matrix, efficient way to calculate row means
rpois(): Generate simulated poisson random values
sapply(): Run lapply, simplify the result.
saveRDS(): Creates an rds file (one object)
sem(): In sem, run a structural equation model
semPaths():
semTable(): In kutils, create an sem table
seq(): Create a sequence of values
sessionInfo(): Print version information about R
sessionInfo(): Print version information about R
set.seed(): Initialize the internal random number generator
set.seed(): Initialize the internal random number generator
setdiff(): Find values in one list that are not in the other
sort(): order a vector from small to large
sqrt(): Calculate the square root
strwidth(): Calculate width needed to write a character string
substitute(): R programming method to replace symbolic values (advanced)
summarize(): In rockchalk, Hmisc, or plyr packages
summary(): R generic to display basic, overall view
t.test(): A basic t.test numeric vectors
table(): Creates cross-tabulation of 1 or more variables
testSlopes(): In rockchalk, creates a J-N display of regression interaction
text(): Add text to the plot region
theme(): In ggplot2, a style element
with(): For a given data frame, run the following instruction