5 * 5

1 + 4 * 5

4 * 5 ^ 2

sin(90)

sin(0.5 * pi)

a <- 1
b <- 2
c <- "c"
x_thingy <- 4

a + b
a * b
a + c
a / x_thingy

ls()

## [1] "a"        "b"        "c"        "x_thingy"

x <- x_thingy
rm(x_thingy)
x

## [1] 4

ls()

## [1] "a" "b" "c" "x"

• Open RStudio and have a look around
• Create a new project
• Create a new R Script: pass code to the console with Ctl-Enter
• Use R as a calculator: what is:

\[ \pi * 9.15^2 \]

• Explore each of the 'panes'
• Find and write down some useful shortcuts (Alt-Shift-K on Windows/Linux)

In R:

• Everything that exists is an object
• Everything that happens is a function

# Assignment of x
x <- 5
x

## [1] 5

# A trick to print x
(x <- 5)

(y <- x)

sin(x)

## [1] -0.9589243

exp(x)

## [1] 148.4132

factorial(x)

## [1] 120

sinx <- sin(x)

x <- c(1, 2, 5)
x

## [1] 1 2 5

x^2

## [1]  1  4 25

x + 2

## [1] 3 4 7

x + rev(x)

x <- c(1, 2, 5)
for(i in x){
  print(i^2)
}

## [1] 1
## [1] 4
## [1] 25

Creating a new vector based on x

for(i in 1:length(x)){
  if(i == 1) x2 <- x[i]^2
  else x2 <- c(x2, x[i]^2)
}
x2

## [1]  1  4 25

R has a hierarchy of data classes, tending to the lowest:

• Binary
• Integer (numeric)
• Double (numeric)
• Character

a <- TRUE
b <- 1:5
c <- pi
d <- "Hello Leeds"

class(a)
class(b)
class(c)
class(d)

ab <- c(a, b)
ab

## [1] 1 1 2 3 4 5

class(ab)

## [1] "integer"

class(c(a, b))

## [1] "integer"

class(c(a, c))

## [1] "numeric"

class(c(b, d))

## [1] "character"

x <- 1:5
y <- 2:6
plot(x, y)

x <- seq(1,2, by = 0.2)
length(x)

## [1] 6

x <- seq(1, 2, length.out = 5)
length(x)

## [1] 5

Working through Chapter 20 of R for Data Science: http://r4ds.had.co.nz/vectors.html

• Work through 20.3

• Challenge: create an atomic vector of 3 characters and an NA

• Challenge: create an atomic vector of 5 numeric vectors

• Challenge: create a list containing logical, character and numeric vectors
  • What happens to the class if you unlist this list?
• Complete all the code examples in 20.4
  • Challenge: what are the outcomes of the following commands?:

x = 1:10
x[c(1, NA)]
x[2 * 3]
x[-2 * 3]

• Run the code in download-data.R
• Check that the files have downloaded and unzipped OK
  • If so: you've used R as a file manager!
• Work through pages 4, 5 and 6 in the Creating-maps-in-R tutorial