In olobiolo/Rdlazer: Resources for Teaching R

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

SESSION

install.packages: install package
uninstall.packages: uninstall package
search: display search path of the current session
library: attach package to current session
detach: remove item from search list; detach(“package:packagename”)
getwd: get working directory
setwd: set working directory; invisibly returns current
ls: list bindings in environment; returns character vector
rm: remove binding

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FILES

getwd: get working directory
setwd: set working directory; invisibly returns current
list.files: get list of files in directory; returns character vector
file.exists: test if file exists; returns logical vector
file.copy: copy file; returns logical vector as report
file.remove: delete file; returns logical vector as report
file.rename: rename file; can move files; returns logical vector as report
dir.exists: test if directory exists; returns logical vector
dir.create: create directory
unlink: delete file or directory

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GENERAL

name <- value: create binding, i.e. define variable , i.e. assign value to name
assign: create binding, i.e. assign value to name
exists: take string and test if object with that name exists
get: take string and return object with that name
rm: remove binding
print: print object (explicit)
names: get/set names
head: print a few first elements of object
str: describe structure of object
ifelse: create vector of two alternative values based on a logical vector
round: round a number
attributes: list object attributes
attr: get/set object attribute
class: get/set class attribute
table: create contingency table of a number of factors
summary: print summary of object
seq: generate sequence of numbers; returns numeric vector
rep: replicate vector elements
apply: apply function to array, splitting along selected dimensions
lapply: apply function to list/vector; returns list
sapply: like lapply but attempts to simplify result, e.g. list of length 1 vectors to vector, list of length 2 vectors to matrix
vapply: like lapply but type of function result must be defined, e.g. length 1 character; for use in programming
mapply: like sapply but cycles over multiple vectors in parallel
tapply: run function on vector split according to another vector
split: split object according to factor(s)
by: run function on object split according to factor(s)
do.call: call a function, passing arguments as a list

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VECTORS

c: build vector (concatenate)
append: append elements to vector
length: get length of vector
typeof: get object type (integer/double/logical/character)
is.numeric: test if object is a numeric vector
is.character: test if object is a character vector
is.factor: test if object is a factor
as.character: convert to character
as.factor: convert to factor
names: get/set names
levels: get/set factor levels
which: which element of logical vector is TRUE; returns integer vector
rev: reverse order of vector
sort: sort vector
order: get order of vector elements that would result in a sorted vector; returns integer vector
duplicated: test whether elements of argument are duplicated; returns logical vector
anyDuplicated: test if any elements of argument are duplicated; returns single integer
unique: get unique values
setNames: set object names; returns copy of object
is.element: test if elements of one vector are elements of another; returns logical vector
%in%: infix operator for is.element

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LOGIC

all: test if all elements of logical vector are TRUE; returns single TRUE/FALSE
any: test if any element of logical vector is TRUE; returns single TRUE/FALSE
identical: test if objects are identical; returns single TRUE/FALSE
all.equal: test if all elements of two vectors are equal (within rounding error); returns TRUE or a summary of differences
is.na: test if elements of argument are NA; returns logical vector
anyNA: test if argument contains NAs; returns single TRUE/FALSE

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LISTS

list: create a list
as.list: convert to list
unlist: convert list to vector
names: get/set names

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SETS

is.element: test if elements of one vector are elements of another; returns logical vector
%in%: infix operator for is.element
union: union of two sets; returns a vector of all elements of both sets
setdiff: (asymmetric) difference between sets; returns vectors of items that are elements of one set but not the other
intersect: intersection of two sets; returns vector of items that are elements of both sets
setequal: test if sets contain the same elements; returns single logical

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DATA

read.table: load data from tabular file
write.table: save data in tabular file
save: save objects in binary file
load: load contents of binary file
cbind: bind columns; add one table to the right of another
rbind: bind rows; add one table at the bottom of another
names: get/set (column) names in data.frame
colnames: get/set column names
rownames: get/set row names
setNames: set object names (column names for data.frames); returns copy of object
head: print a few first elements of object
dim: get object dimensions
str: describe structure of object
duplicated: test whether elements of argument are duplicated; returns logical vector
anyDuplicated: test if any elements of argument are duplicated; returns single integer
unique: get unique values
complete.cases: which cases have no missing values; returns logical vector
summary: print summary of object

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STRINGS

nchar: get number of characters in string
tolower: convert string lo lowercase
toupper: convert string lo uppercase
paste: concatenate strings
substring: get substring
strsplit: split strings; returns list
startsWith: test whether string starts with string
endsWith: test whether string ends with string
grep: test which elements of vector contain regex; returns numeric vector or character vector
grepl: test which elements of vector contain regex; returns logical vector
gsub: substitute all occurrences of regex in vector with string
sub: substitute first occurrence of regex in each element of vector with string

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STATISTICS

sum: add elements of vector; returns single numeric
mean: average elements of vector; returns single numeric
median: compute median of vector; returns single numeric
max: get highest value in vector
min: get lowest value in vector
summary: returns Tukey five of numeric vector
rnorm: generate a sample from a normal distribution
runif: generate a sample from a uniform distribution
sample: randomly select elements of vector
lm: build linear model
coef: get coefficients of linear model
residuals: get residuals of model
predict: generate prediction based on a model
shapiro.test: test it sample comes from normal distribution
t.test: run Student’s test for difference of mean
wilcox.test: run Mann-Whitney-Wilcoxon test for difference of mean
qqplot: generate quantile-quantile plot to compare two samples’ parent distributions