Vectors of numbers and defining variables

Introduction

Introduction

Filter

Filter()

subsetting vectors eg x[!is.na(x)].

slices

Reduce and length

Reduce()

length()

Map

Map()

Type checking

is.[x]

typeof

Random numbers

random numbers

set.seed

Sorting vectors

Factors on vectors

factors in r: ordered, unordered

Casting between types

as.name

as.[x]

Defining variables

c function is concatenate

a =  c(1, 2, 3)
a <- c(1, 2, 3)

defining using eg 1L to get variable types

nested vector just a vector

y <- c(  1, 2 , 3)
y <- c(c(1, 2), 3)

y <- c(x, 1).

complex numbers, other number types in r

getting sequences, 1:30 etc

seq() function rep() function

Using variables on the right hand side

is R copy on write? what happens if you set y = x? copies or just two pointers?

a <- c(1, 2, 3)
b <- c(a, 1)

a <- c(1, 2, 3)
b <- a + 1

Substituting by conditions

substituting by conditions. eg

y[y<0]<-0

Arithmetic

Logic

and or in R

SORT

what happens when make anything? all on heap with variable just being pointer?

infinity in R

inf eg 1/0 (-inf?)

+ most simple is a vector + arithmetic page: * does stuff for each entry in vector eg x + 2 * summary stuf for vector. sum, min, max, len etc + null, na etc in R + nan

+ see what name points to: * eg if x <- c(1,2,3) * y <- x * addresses are same * if modify, addresses are different * only creates copy when needs to * aka copy on modify * r objects generally immutable * tra

overflows of numbers in r. eg what happens if int gets too big

dates and times in base R (other data types, int log etc)