ARTICLES

R lang

By adam

operators

Exponent: ^ Bit: & | Conditional: && ||

difference between = and <- operators

Just use =

vectors (range)

  • everything is a vector
  • 1:9, 1:2:9, c(1,3,2,-8.1)
  • c() for concat

vector addition

  • v1 + v2 : element wise

matrices

  • matrix(c(1,2,3,4,5,6,7,8,9), nrow=3)
  • nrow is the number of rows or ncol for number of columns
  • fills in column order, i.e. [[1,4,7],[2,5,8],[3,6,9]]
  • matrix(1:9, nrow=3, byrow=T) : fills in row order

matrix multiplication

  • m1 %*% m2

transpose

  • t(m1)

slicing

  • m1[1,3]
  • m1[,3] : all elements on third column
  • m1[1,] : all elements on first rows
  • m1[,-2] : all but the second column
  • m1[1,1] = 15
  • m1[,2:3] = 1 : set columns 2 and 3 to 2
  • m1[,2:3] = 4:9 : set columns 2 and 3 to col2:4,5,6, col3:7,8,9
  • m1[m1>5] : filter elements in m1 that are greater than 5
  • m1[m1>5] = 3 : set all elements greater than 5 to 3

loops

for(i in 1:3) { print(i) } while(sum(v1)>=5) {}

control

if(m1[i,1]>=2){}

ternary if

ifelse(a==1,1,0)

types

class(1) class(c(1,2)) : numeric class(1:3) : integer : more specific, and saves footprint class(1.1:3) : numeric class(“hello”) : character class(c(“r”,“g”)) : character class(c(1,“r”)) : character class(c(T,F)) : logical

NA : Not available (null)

class(NaN) : numeric class(NA) : logical

vector

vector(mode="logical”,3)

  • this class can only contain one type, ‘numeric’, ‘character’, or ‘logical’

matrix

is a 2-D ‘vector’ class(m1) : matrix

array

  • can only have one data type like vector and matrix
  • arrays can also store matrices, data frames and lists
  • can be multidimensional

array(1:16, dim=c(4,2,2))

dataframe

df = data.frame(c(1,2,3),c(T,F,F),row.names=c(“r”,“g”,“b”)) names(df)[1] = “col1” names(df)[2] = “col2”

list

a = list(“a”,1”,F) use double [] to access element a = list(category1=c(1), category2=c(T), category3=c(“r”)) a$category1

hierarchy

conversion

as.vector(), as.logical(), as.character

file system

getwd() : pwd setwd() : cd p = read.csv(“some.csv”, header=TRUE) row.names(p) = p[,1] p = p[,-1] read.delim(“filename.xxx”, header=TRUE, sep=”;', dec=”.")

write.csv(var1, file="some.csv”) write.table(df, file="some.csv”, sep=” “) save(var1, var2, file="some.rdata”)

rdata

  • extension: .rdata
  • load(“some.rdata”)

plotting

plot(x,y) x11() : new window par(mfrow=c(1,2), bg="grey”, bty="n”, cex=.75)

  • mfrow : subplot
  • bty : boundary box
  • cex : text ratio

plot(x,y,xlab="1:9”, ylab="9:1”, main="title”, col="red”, pch=3)

  • pch : shape of the points

hist(p[,1], main=colnames(p)[1], xlab="xlabel”, breaks=c(0,.5,.7,.8,.9,1) boxplot(p) lines(x,y) abline(coef=c(intercept, slope), v=vertical_x, h=horizontal_y) points(1:5,c(4,4,4,4,4), pch=1:5, col=1:5) par(new=T) legend(x="topright”, legend=c(“r”,“g”,“b”), lwd=2, col=1:2, bg="grey”)

  • lwd : linewidth

pdf(“some.pdf”) dev.off()

help

?plot

functions

abs(), sqrt() seq(0,8,2) rep(c(0,2), 5) length(c(1,2,3)) system.time((seq1 = seq(0,1e6,1))) var() : variance mean(), median() sample(c(0,1), 10, replace=TRUE, prob = c(.5,.5)) which(vec==1) : return indices where T t.test(1:5, 5:10) : student t-test runif(5, min=0, max=1) : random sampling of 5 numbers, unif([0,1]) ls() : what objects are in workspace rm(var) : remove a variable q() : quit

custom functions

doublex <- function(x,y=10) { return(2) }dx

running script from file

source(“some.r”)

Installing packages

install.packages(“install.load”) library(install.load) install_load(“somepackage”) library(somepackage) detach(“package:somepackge, unload=TRUE)

jsonlite

install_load(‘jsonlite’) a = jsonlite::read_json(‘jobj.json’) a$Diameter$mean

dict package

if (!require(“devtools”)) install.packages(“devtools”) devtools::install_github(“mkuhn/dict”)

tidyverse

Warning messages: 1: In install.packages(“tidyverse”) : installation of package ‘curl’ had non-zero exit status 2: In install.packages(“tidyverse”) : installation of package ‘httr’ had non-zero exit status 3: In install.packages(“tidyverse”) : installation of package ‘rvest’ had non-zero exit status 4: In install.packages(“tidyverse”) : installation of package ‘tidyverse’ had non-zero exit status

sudo aptitude install libcurl4-openssl-dev libxml2-dev https://stackoverflow.com/questions/31008877/unable-to-install-rvest-package

rss autocomplete

https://ess.r-project.org/Manual/ess.html#Installation

tidyverse

https://github.com/tidyverse/stringr

r for dummies

https://www.dummies.com/programming/r/how-to-combine-logical-statements-in-r/