Reverse the values of an Object in R Programming – rev() Function

rev() function in R Language is used to return the reverse version of data objects. The data objects can be defined as Vectors, Data Frames by Columns & by Rows, etc.

Syntax: rev(x)

Parameter:
x: Data object

Returns: Reverse of the data object passed

Example 1:

# R program to reverse a vector

# Create a vector
vec <- 1:5
vec

# Apply rev() function to vector
vec_rev <- rev(vec)
vec_rev

Output:

[1] 1 2 3 4 5
[1] 5 4 3 2 1

Example 2: Reverse Columns of a Data Frame

# R program to reverse
# columns of a Data Frame

# Creating a data.frame
data <- data.frame(x1 = 1:5,
                   x2 = 6:10,
                   x3 = 11:15)
data

# Print reversed example data frame
data_rev <- rev(data)
data_rev

Output:

   x1 x2 x3
1  1  6 11
2  2  7 12
3  3  8 13
4  4  9 14
5  5 10 15
 
  x3 x2 x1
1 11  6  1
2 12  7  2
3 13  8  3
4 14  9  4
5 15 10  5

Example 3: Reverse Rows of a Data Frame

# R program to reverse
# rows of a data frame

# Creating a data frame
data <- data.frame(x1 = 1:5,
                   x2 = 6:10,
                   x3 = 11:15)
data

# Calling rev() & apply() functions combined
data_rev_row_a <- apply(data, 2, rev)
data_rev_row_a

# Alternative without rev()
data_rev_row_b <- data[nrow(data):1, ]
data_rev_row_b

Output:

  x1 x2 x3
1  1  6 11
2  2  7 12
3  3  8 13
4  4  9 14
5  5 10 15
     x1 x2 x3
[1,]  5 10 15
[2,]  4  9 14
[3,]  3  8 13
[4,]  2  7 12
[5,]  1  6 11
  x1 x2 x3
5  5 10 15
4  4  9 14
3  3  8 13
2  2  7 12
1  1  6 11