R Vectors

R vectors are the same as the arrays in C language which are used to hold multiple data values of the same type. One major key point is that in R the indexing of the vector will start from ‘1’ and not from ‘0’. We can create numeric vectors and character vectors as well.

Types of R vectors

Vectors are of different types which are used in R. Following are some of the types of vectors:

Numeric vectors: Numeric vectors are those which contain numeric values such as integer, float, etc.

Example:

# R program to create numeric Vectors

# creation of vectors using c() function.

v1<- c(4, 5, 6, 7)

# display type of vector

typeof(v1)

# by using 'L' we can specify that we want integer values.

v2<- c(1L, 4L, 2L, 5L)

# display type of vector

typeof(v2)

Output:

[1] "double"

[1] "integer"

Character vectors: Character vectors in R contain alphanumeric values and special characters.

Example:

# R program to create Character Vectors

# by default numeric values

# are converted into characters

v1<- c('geeks', '2', 'hello', 57)

# Displaying type of vector

typeof(v1)

Output:

[1] "character"

Logical vectors: Logical vectors in R contain Boolean values such as TRUE, FALSE and NA for Null values.

Example:

# R program to create Logical Vectors

# Creating logical vector

# using c() function

v1<- c(TRUE, FALSE, TRUE, NA)

# Displaying type of vector

typeof(v1)

Output:

[1] "logical"

Complex Vectors

Vectors containing complex values.

Example:

comp_vec <- c(12+1i,3i,5+4i,4+9i,6i)  

print(comp_vec)

Output:

[1]12+1i  0+3i  5+4i  4+9i  0+6i

Creating a vector

There are different ways of creating R vectors. Generally, we use ‘c’ to combine different elements together.

Example:

# R program to create Vectors

# we can use the c function

# to combine the values as a vector.

# By default the type will be double

X<- c(61, 4, 21, 67, 89, 2)

cat('using c function', X, '\n')

# seq() function for creating

# a sequence of continuous values.

# length.out defines the length of vector.

Y<- seq(1, 10)

cat('using seq() function', Y, '\n')

Y<- seq(1, 10,2)

cat('using seq() function', Y, '\n')

Y<- seq(1, 10, length.out = 5)

cat('using seq() function', Y, '\n')

# use':' to create a vector

# of continuous values.

Z<- 2:7

cat('using colon', Z)

Output:

using c function 61 4 21 67 89 2 

using seq() function 1 2 3 4 5 6 7 8 9 10 

using seq() function 1 3 5 7 9 

using seq() function 1 3.25 5.5 7.75 10 

using colon 2 3 4 5 6 7

Length of R vector

# Create a numeric vector

x <- c(1, 2, 3, 4, 5)

# Find the length of the vector

length(x)

# Create a character vector

y <- c("apple", "banana", "cherry")

# Find the length of the vector

length(y)

# Create a logical vector

z <- c(TRUE, FALSE, TRUE, TRUE)

# Find the length of the vector

length(z)

Output:

[1] 5

[1] 3

[1] 4

Accessing R vector elements

Accessing elements in a vector is the process of performing operation on an individual element of a vector. There are many ways through which we can access the elements of the vector. The most common is using the ‘[]’, symbol.

Note: Vectors in R are 1 based indexing unlike the normal C, python, etc format.

Example:

# R program to access elements of a Vector

# accessing elements with an index number.

X<- c(2, 5, 18, 1, 12)

cat('Using Subscript operator', X[2], '\n')

# by passing a range of values

# inside the vector index.

Y<- c(4, 8, 2, 1, 17)

cat('Using combine() function', Y[c(4, 1)], '\n')

Output:

Using Subscript operator 5 

Using combine() function 1 4 

Modifying a R vector

Modification of a Vector is the process of applying some operation on an individual element of a vector to change its value in the vector. There are different ways through which we can modify a vector:

Example:

# R program to modify elements of a Vector

# Creating a vector

X<- c(2, 7, 9, 7, 8, 2)

# modify a specific element

X[3] <- 1

X[2] <-9

cat('subscript operator', X, '\n')

# Modify using different logics.

X[1:5]<- 0

cat('Logical indexing', X, '\n')

# Modify by specifying

# the position or elements.

X<- X[c(3, 2, 1)]

cat('combine() function', X)

Output:

subscript operator 2 9 1 7 8 2 

Logical indexing 0 0 0 0 0 2 

combine() function 0 0 0

Deleting a R vector

Deletion of a Vector is the process of deleting all of the elements of the vector. This can be done by assigning it to a NULL value.

Example:

# R program to delete a Vector

# Creating a Vector

M<- c(8, 10, 2, 5)

# set NULL to the vector

M<- NULL

print('Output vector')

print(M)

Output:

[1] "Output vector"

NULL

Sorting elements of a R Vector

sort() function is used with the help of which we can sort the values in ascending or descending order.

# R program to sort elements of a Vector

# Creation of Vector

X<- c(8, 2, 7, 1, 11, 2)

# Sort in ascending order

A<- sort(X)

cat('ascending order', A, '\n')

# sort in descending order

# by setting decreasing as TRUE

B<- sort(X, decreasing = TRUE)

cat('descending order', B)

Output:

ascending order 1 2 2 7 8 11 

descending order 11 8 7 2 2 1

Negative Indexing

You can also use negative index numbers to access all items except the ones specified:

Example:
fruits <- c("banana", "apple", "orange", "mango", "lemon")

# Access all items except for the first item
fruits[c(-1)]

Output:

[1] "apple"  "orange" "mango"  "lemon" 

Repeat Vectors

To repeat vectors, use the rep() function:

Example:

repeat_each <- rep(c(1,2,3), each = 3)

print(repeat_each)

Output:

[1] 1 1 1 2 2 2 3 3 3

repeat_times <- rep(c(1,2,3), times = 3)

print(repeat_times)

Output:

[1] 1 2 3 1 2 3 1 2 3

repeat_indepent <- rep(c(1,2,3), times = c(5,2,1))

print(repeat_indepent)

Output:

[1] 1 1 1 1 1 2 2 3

Generating Sequenced Vectors

One of the examples on top, showed you how to create a vector with numerical values in a sequence with the : operator:

Example

numbers <- 1:10

print(numbers)

Output:

[1]  1  2  3  4  5  6  7  8  9 10

To make bigger or smaller steps in a sequence, use the seq() function:

Example

numbers <- seq(from = 0, to = 100, by = 20)

print(numbers)

Output:

[1]   0  20  40  60  80 100

Note: The seq() function has three parameters: from is where the sequence starts, to is where the sequence stops, and by is the interval of the sequence.

Loop Over a R Vector

We can also access all elements of the vector by using a for loop. For example,

In R, we can also loop through each element of the vector using the for loop. For example,

numbers <- c(1, 2, 3, 4, 5) # iterate through each elements of numbers 

for (number in numbers) { 

 print(number) 

}

Output:

[1] 1

[1] 2

[1] 3

[1] 4

[1] 5

Vector Arithmetic

R performs arithmetic operations on vectors memberwise. This means that the operations are performed on each member. For example:

Adding a Constant

vec=c(1,2,3)

vec_plus_three <- vec+3 

print( vec_plus_three)

Output:

[1]4 5 6

Subtracting a constant:

vec=c(1,2,3)

vec_min_one <- vec-1 

print(vec_min_one)

Output:

[1]0 1 2

Multiplication with a constant

multivec <- vec*2

print(multivec)

Output:

[1] 2 4 6

We can also perform an arithmetic operation like an addition of two vectors of equal length. This adds the corresponding members in the two vectors. For example

 Adding two vectors

vec1=c(1,2,3)

vec2=c(1,2,3)

addv<- vec1+vec2

print(addv)

Output:

[1] 2 4 6

Subtracting two vectors

vec1=c(1,2,3)

vec2=c(1,2,3)

subvv<- vec1-vec2

print(subv)

Output:

[1] 0 0 0

Multiplying two vectors

vec1=c(1,2,3)

vec2=c(1,2,3)

mulv<- vec1*vec2

print(mulv)

Output:

[1] 1 4 9

Division of Vector

vec1=c(1,2,3)

vec2=c(1,2,3)

divv<- vec1/vec2

print(divv)

Output:

[1] 1 1 1

If the two vectors are of unequal length, the shorter one will be recycled to match the longer vector.

vec1=c(1,2,3,4)

vec2=c(1,2)

sumv<- vec1+vec2

print(sumv)

Output:

[1] 2 4 4 6