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.
|
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 |
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:
|
A |
B |
C |
product |
---|---|---|---|---|
1. |
5 |
6 |
1 |
60 |
2. |
6 |
4 |
2 |
48 |
3. |
7 |
3 |
3 |
63 |
4. |
5 |
4 |
7 |
140 |
5. |
6 |
2 |
8 |
96 |
6. |
9 |
6 |
9 |
486 |
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.
R
# 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.
R
# 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.
R
# 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.
R
# apply(X,MARGIN,FUN,...) single <- apply (df,1,product ) # adding product vector to dataframe cbind (df,product = single) |
Output:
Below is the full implementation:
R
# 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:
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