R Program to reverse a number - rev() Function

In this article, we will discuss how to reverse a number in R Programming Language. To reverse a number we will use in built method in R.

In R Programming Language rev() function 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

R program to reverse a number

# 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

R program to 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

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

Conclusion

The rev function provides a concise and efficient solution for reversing the elements of a vector. It is particularly useful in scenarios where the order of elements needs to be reversed for further analysis or presentation.