Apply Function to each Row in R DataFrame

In this article, we will discuss how to apply a function to each row in a data frame in R Programming Language. Let's take an example for a better understanding.

Example:

Suppose we have a dummy dataset with A, B, C as column names and some numeric value as rows.

And we want to apply a function that will return the product of each row value, then the resultant data frame should look like this:

Apply function to each row in R Data frame:

Approach: Using apply function

apply() is used to compute a function on a data frame or matrix. The purpose of using apply() function is to avoid the use of looping. apply() function returns output as a vector.

Syntax: apply(x, margin, func)

Parameters:
x: Array or matrix
margin: dimension on which operation is to be applied
func: operation to be applied

Stepwise implementation:

Step 1: Create a dummy dataset.

# Apply function to each row in r Dataframe

# Creating dataset 
# creating first column
x <- c(5, 6, 7, 5, 6, 9)

# creating second column
y <- c(6, 4, 3, 4, 2, 6)

# creating third column
z <- c(1, 2, 3, 7, 8, 9)

# creating dataframe
df <- data.frame(A = x, B = y, C = z)

display(df)

Output:

  A B C
1 5 6 1
2 6 4 2
3 7 3 3
4 5 4 7
5 6 2 8
6 9 6 9

Step 2: Create a custom function for calculating products. 

# creating function to computer product
product = function(x, output){
  
  # accessing elements from first column
  A = x[1]
  
  # accessing elements from second column
  B=x[2]
  
  # accessing elements from third column
  C= x[3]
  
  # return product 
  return(A*B*C)
}

 Note: Here we are just defining the function for computing product and not calling, so there will be no output until we call this function. 

Step 3: Use apply the function to compute the product of each row. 

Syntax: (data_frame, 1, function,...)

Now we are calling the newly created product function and returns the product using apply function. 

# apply(X,MARGIN,FUN,...)
apply(df,1,product  )

Output:  

[1]  30  48  63 140  96 486

Note: apply() return product as a vector list. So we have to add it to the data frame using cbind (column bind).

Step 4: Append product list to the data frame. 

# apply(X,MARGIN,FUN,...)
single <- apply(df,1,product  )

# adding product vector to dataframe
cbind(df,product = single)

Output:

Below is the full implementation:

# Apply function to each row in r Dataframe

# Creating dataset 
# creating firs column
x <- c(5,6,7,5,6,9)

# creating second column
y <- c(6,4,3,4,2,6)

# creating third column
z <- c(1,2,3,7,8,9)

# creating dataframe
df <- data.frame(A=x,B=y,C=z)

# creating function to computer product
product = function(x,output){
  
  # accessing elements from first column
  A = x[1]
  
  # accessing elements from second column
  B=x[2]
  
  # accessing elements from third column
  C= x[3]
  
  # return product 
  return(A*B*C)
}

# apply(X,MARGIN,FUN,...)
apply(df,1,product  )

# apply(X,MARGIN,FUN,...)
single <- apply(df,1,product  )

# adding product vector to dataframe
cbind(df,product = single)

Output: