R – Vector

R programming is one of the most popular languages when it comes to data science, statistical computations or scientific research. R programming is widely used in machine learning and it is very efficient and user-friendly. It provides flexibility in doing big statistical operations with a few lines of code.

Vectors in R 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 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.

  # 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 contain alphanumeric values and special characters.

  # 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 contain boolean values such as TRUE, FALSE and NA for Null values.

  # 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"

Creating a vector

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

# 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, 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 3.25 5.5 7.75 10 
using colon 2 3 4 5 6 7

Accessing 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.

# 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')

# using logical expressions
Z <- c(5, 2, 1, 4, 4, 3)
cat('Using Logical indexing', Z[Z>4])

Output

Using Subscript operator 5 
Using combine() function 1 4 
Using Logical indexing 5

Modifying a 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:

# 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[X>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 2 0 1 0 0 2 
combine() function 1 0 2

Deleting a 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.

# R program to delete a Vector

# Creating a Vector
M <- c(8, 10, 2, 5)

# set NULL to the vector
M <- NULL
cat('Output vector', M)

Output:

Output vector NULL

Sorting elements of a 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