Basic mathematis (cont. 1)

1. Basic Math (cont.1)

## Precedence

1+2+3/3

## [1] 4

(1+2+3)/3

## [1] 2

2. Variables

m <- 1
n <- "Hello World"
MyVector <- c(1,2,3,4)
AnotherVector <- c("a","b","c")

3. Numbers

4. Integers

x <- 5
y <- -2
z <- 5.8 #Note 5.8 is clearly not an integer
is.integer(y)

## [1] FALSE

k <- as.integer(z)
is.integer(z)

## [1] FALSE

5. Numerics

j = 1.5
k = 23.456
str(k)

##  num 23.5

6. Vectors

# we want to store lists of numbers all in one place. 
# One way to do this is using vectors in R. Vectors store several numbers.

a <- c(1,2,3,4,5)
b <- c(1234,2345,3456,4567)

6.1 Indexing an element in a vector

b[1]

## [1] 1234

b[3]

## [1] 3456

6.2 Indexing a range of elements in a vector

b[2:4]

## [1] 2345 3456 4567

6.3 Replacing an element in a vector

h <- c("You are so cute", 36, 99, 105)
h[1] <- "You are so smart"

6.4 Adding an element to the vector

h <- c("You are so cute", 36, 99, 105)

h_new1 <- c(h, "You are also smart")

h_new2 <- c("You are also smart", h)

h_new3 <- c(h[1:1], "You are also smart", h[2:4]) #insert a new element at position 2 of the vector

6.5 Checking the number of elements in your vector

length(h)

## [1] 4