This page contains listings of some R functions and commands by category. The format is pretty stupid but can't do much better with wiki formatting, sorry.
Workspace and help
Workspace and help
| function name
|
functionality
|
| getwd()
|
get working directory
|
| setwd(dir)
|
set working directory to dir
|
| help(topic), ?topic
|
get help on topic, usually function name
|
| help.search("keyword")
|
search for help
|
| help.start()
|
HTML help start page
|
| demo()
|
list available demonstrations
|
| save(..., file), load(file)
|
save and load objects
|
| savehistory(file), loadhistory(file)
|
save and load command history
|
| source(file)
|
execute commands from file
|
| list.files(dir), dir(dir)
|
list files in directory dir
|
| q()
|
quit R
|
Objects
Objects
| function name
|
functionality
|
| mode(x)
|
mode of x
|
| ls(), objects()
|
list objects in memory
|
| rm(x), rm(list = ls())
|
remove x or all objects
|
| exists(x)
|
test if object x exists in memory
|
| as.numeric(x), as.list(x), as.character(x), as.factor(x), as.data.frame(x),...
|
coerce mode of object x
|
| is.numeric(x), is.na(x), ...
|
test mode of object x
|
| identical(x, y)
|
test if objects are identical
|
| return(invisible(x))
|
return invisible copy (doesn't print)
|
Packages
Packages
| function name
|
functionality
|
| install.packages(name)
|
download and install package name
|
| download.packages(name, dir)
|
download package name into dir
|
| library(name), require(name)
|
load package name
|
| data(name)
|
load dataset name
|
| .libPaths(dir)
|
add directory dir to library paths
|
| sessionInfo()
|
list loaded packages
|
Flow and control and function definition
Flow and control and function definition
| function name
|
functionality
|
| if(logical_expression) {expression_1} else {expression_2}
|
if then else
|
| for (x in vector) {expression}
|
loop through elements of vector as x
|
| while (logical_expression) {expression}
|
while loop
|
| name <- function(input1, ...) {expression_1; ...; return(output)}
|
function definition
|
| stop(message)
|
cease processing and print message
|
| browser()
|
stop to inspect objects for debugging
|
| system.time(expression)
|
report runtime for expression
|
Mathematical and logical operators and functions
Mathematical and logical operators and functions
| function name
|
functionality
|
| +, -, *, /, ^, %%, %/%
|
algebraic operators, %% for remainder of integer division, %/% for integer division i.e. rounded down to 0 decimal places
|
| <, >, <=, >=, ==, !=
|
comparison operators (less than, greater than, less or equal, greater or equal, equal, not)
|
| &, |, !
|
logical operators (and, or, not)
|
| &&, ||
|
and/or evaluated progressively from left
|
| xor(A, B)
|
exclusive or (A or B but not both)
|
| ifelse(condition, x, y)
|
choose x or y elementwise
|
| sin(x), cos(x), tan(x)
|
sine, cosine and tangent
|
| asin(x), acos(x), atan(x)
|
inverse sine, cosine and tangent
|
| exp(x), log(x)
|
exponential and logarithm base e
|
| sqrt(x)
|
square root
|
| abs(x)
|
absolute value
|
| pi
|
3.1415926...
|
| ceiling(x)
|
smallest integer >= x
|
| floor(x)
|
largest integer <= x
|
| all.equal(x, y)
|
almost equal
|
| round(x, k)
|
round x to k digits
|
| deriv(expression, vars)
|
symbolic differentiation
|
Vectors
Vectors
| function name
|
functionality
|
| x[i]
|
select subvector from x using index vector i
|
| x[logical], subset(x, subset)
|
select subvector using logical vector
|
| c(x, y,...)
|
combine vectors x, y, ...
|
| seq(from, to, by), from:to
|
generate an arithmetic sequence
|
| rep(x, times)
|
generate repeated values
|
| length(x)
|
length of x
|
| which(x)
|
indices of TRUE elements of x
|
| sum(...)
|
sum over vector(s)
|
| prod(...)
|
product over vector(s)
|
| cumsum(x), cumprod(x)
|
cumulative sum and product
|
| min(...), max(...)
|
minimum and maximum
|
| sort(x)
|
sort a vector
|
| mean(x)
|
sample mean
|
| var(x), sd(x)
|
sample variance and standard deviation
|
| order(x)
|
rank order of elements of x
|
Matrices
Matrices
| function name
|
functionality
|
| matrix(data, nrow, ncol, byrow)
|
create a matrix
|
| rbind(...), cbind(...)
|
combine rows or columns
|
| diag(x)
|
create a diagonal matrix
|
| %*%
|
matrix multiplication
|
| nrow(A), ncol(A)
|
number of rows and columns
|
| colMeans(A), colSums(A)
|
column means or sums
|
| dim(A)
|
dimensions of x
|
| det(A)
|
determinant
|
| t(A)
|
transpose
|
| solve(A, b)
|
solution of A x == b
|
| solve(A)
|
matrix inverse
|
| array(data, dim)
|
create a multidimensional array
|
| reshape(data, idvar="id", timevar="a", v.names="b", direction="wide")
|
reshape long data to wide (b=the values you want to show up under your new columns, id=the id that you want to group your data record by; a=the values that you want to make up the new columns; however many distinct values are in this column determines the number of new columns; wide= the destination or resulting format we want)
|
| melt(data, id.vars = c("a"), variable_name = "b"
|
reshape data wide to long; you need library(reshape); a=the values you want be indices; b the name of result column
|
Dataframes, factors and lists
Dataframes, factors and lists
| function name
|
functionality
|
| data.frame(...)
|
create a dataframe
|
| str(x)
|
summarise structure of x
|
| names(x)
|
names of x
|
| dim(x)
|
number of rows and columns of x
|
| attach(x)
|
copy dataframe objects into workspace
|
| detach(x)
|
delete dataframe objects from workspace
|
| factor(x)
|
create a factor
|
| levels(x)
|
select levels of factor x
|
| list(...)
|
create a list
|
| unlist(x)
|
flatten list x into a vector
|
| apply(x, i, f, ...)
|
apply function f over index i of array x
|
| sapply(x, f, ...)
|
apply function f to x and return a vector
|
| lapply(x, f, ...)
|
apply function f to x and return a list
|
| tapply(x, i, f, ...)
|
apply function f to subvectors of x given by levels of factor i
|
| mapply(f, ...)
|
apply function f to multiple arguments
|
Input and output
Input and output
| function name
|
functionality
|
| scan(file, what, n, sep, skip)
|
read from a file (or keyboard)
|
| read.table(file)
|
read file in table format into dataframe
|
| read.csv(file)
|
read comma separated data (read.table is recommended instead)
|
| read.delim(file)
|
read tab-delimited data (read.table is recommended instead)
|
| readline(prompt)
|
read a line of text from the console i.e. user input
|
| show(object)
|
display object on screen
|
| head(object)
|
first few lines of object
|
| tail(object)
|
last few lines of object
|
| print(object), object
|
print object
|
| options(digits = x)
|
display x digits in output
|
| cat(..., file)
|
concatenate and write
|
| format(x, digits, nsmall, width)
|
format x for output
|
| paste(..., sep = " ")
|
paste strings together with separator sep
|
| write(x, file, append = FALSE)
|
write to a file (or screen)
|
| sink(file)
|
redirect output to a file
|
| dump("x", file)
|
write text representation of x
|
| write.table(x, file)
|
write dataframe x to a file
|
Plotting
Plotting
| function name
|
functionality
|
| plot(x, y)
|
plot y against x
|
| :type = "?"
|
determine the type:
|
| ::"p", "l", "b"
|
for points, lines or both
|
| ::"c"
|
for the lines part alone of "b"
|
| ::"o"
|
for both lines and points overplotted
|
| ::"h"
|
for vertical lines (histogram like plot)
|
| ::"s", "S"
|
for step function, across/op or reverse
|
| ::"n"
|
no data plotted, only axes
|
| :main = "title"
|
provides plot title
|
| :xlim = c(a,b)
|
set lower and upper limits of x-axis
|
| :ylim = c(a,b)
|
set lower and upper limits of y-axis
|
| :xlab = "?", ylab = "?"
|
provide label for x-axis and y-axis
|
| :pch = k
|
set shape of points (k from 1 to 25)
|
| :lwd = ?
|
set line width, default 1
|
| :col = "?"
|
set line and point colour
|
| colour(), color()
|
list R colours
|
| lines(x, y)
|
add lines to plot
|
| abline(h), abline(v)
|
draw horizontal and vertical lines
|
| points(x, y)
|
add points to plot
|
| text(x, y, labels)
|
place text on plot
|
| curve(f, from, to)
|
plot f
|
| par(?)
|
set graphical parameters:
|
| :mfrow = c(nr, nc)
|
create grid of plots with nr rows and nc columns filled by row (mfcol fills by col)
|
| :oma = c(b, l, t, r)
|
create outer margin around each plot
|
| :mar = c(b, l, t, r)
|
create margin around each plot
|
| :las = 1
|
make y-axis labels horizontal
|
| :pty = "s"
|
force the plot shape to be square
|
| :cex = x
|
magnify symbols and text by a factor x
|
| :bty = "?"
|
determine box type drawn around plot
|
Random numbers and probability distributions
Random numbers and probability distributions
| function name
|
functionality
|
| ddist(x, p1, ...)
|
P(X=x) or f(x)
|
| pdist(q, p1, ...)
|
P(X<=q)
|
| qdist(p, p1, ...)
|
p-th quantile, equivalently 100%-point
|
| rdist(n, p1, ...)
|
pseudu-random numbers
|
| dist p1, ...
|
distribution and parameters
|
| :unif min = 0, max = 1
|
uniform
|
| :binom size, prob
|
binomial
|
| :geom prob
|
geometric
|
| :hyper m, n, k
|
hypergeometric
|
| :nbinom size, prob
|
negative binomial
|
| :poist lambda
|
Poisson
|
| :exp rate
|
exponential
|
| :chisq df
|
chi square
|
| :gamma shape, rate
|
gamma
|
| :norm mean, sd
|
normal
|
| :t df
|
t distribution
|
| :weibull shape, scale
|
Weibull
|
| set.seed(seed)
|
set position in pseudo-random sequence
|
| .Random.seed
|
state if the random number generator
|
| RNGkind()
|
which random number generator?
|
| sample(x, n, replace = TRUE)
|
sample size n from x
|
Statistical tests
References
Most of the listings are a pretty straight rip-off from the last pages of the book "Introduction to Scientific Programming and Simulation Using R" by Owen Jones, Robert Maillardet and Andrew Robinson, an excellent book by the way. Added some specifics and will edit the format later, so this is only a quick template, maybe.
