List of R functions

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Revision as of 07:06, 5 May 2011 by Teemu R (talk | contribs) (Mathematical and logical operators and functions)
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This page contains listings of some R functions and commands by category.

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), ... 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
, ! 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 3.145926...
ceiling(x) smallest integer >= x
floor 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 using index vector
x[logical], subset(x, subset) select subvector using logical vector
c(...) combine vectors
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

Statistical tests

Statistical tests
function name functionality
t.test en:Student's t-test
aov en:Analysis of variance