## Vectors

Contains a set of values. These include vec_num, number vector and vec_char whwhich is a character vector. c() combines the elements of a vector and <- assigns a vector to a variable.

vec_num <- c(1, 5, 6, 3)
vec_num
##  1 5 6 3
vec_char <- c("apple", "banana", "mandarin", "melon")
vec_char
##  "apple"    "banana"   "mandarin" "melon"

Once we have created a vector, we can extract its elements using the [] operator. For instance, you can extract the first element ,

vec_char <- c("apple", "banana", "mandarin", "melon")
vec_char
##  "apple"

or the first 3 elements [1:3].

vec_char[1:3]
##  "apple"    "banana"   "mandarin"

## Some functions

### Arithmetic, Multiplication, Division, Subtraction

vec_num2 <- vec_num + 2
vec_num3 <- vec_num / 2
vec_num4 <- vec_num * 4
vec_num5 <- vec_num - 1

vec_num
##  1 5 6 3
# Addition

vec_num2
##  3 7 8 5
# Division

vec_num3
##  0.5 2.5 3.0 1.5
# Multiplication

vec_num4
##   4 20 24 12
# Subtraction

vec_num5
##  0 4 5 2

## Comparing vectors using relational operators (returns TRUE or FALSE)

vec_logi_gt5 <- vec_num >= 5
vec_logi_gt5
##  FALSE  TRUE  TRUE FALSE

We can do this using the equality operator only on character vectors

vec_logi_apple <- vec_char == "apple"
vec_logi_apple
##   TRUE FALSE FALSE FALSE

We can also concatenate vector elements using paste().

vec_char2 <- paste(c("red", "yellow", "orange", "green"), vec_char)
print(vec_char2)
##  "red apple"       "yellow banana"   "orange mandarin" "green melon"

We can also set names to the elements of a numeric vector

names(vec_num) <- vec_char
print(vec_num)
##    apple   banana mandarin    melon
##        1        5        6        3

## Data Frames

Data Frames combine multiple vectors to construct a data set. However, though vectors can be of different types, they can only be combined if they have the same lengths.

dat_fruit <- data.frame(name = vec_char, count = vec_num)
print(dat_fruit)
##              name count
## apple       apple     1
## banana     banana     5
## mandarin mandarin     6
## melon       melon     3