Finding row index containing maximum value using R

This blog explains the way to find the row index that contains the maximum value using R Language, along with illustrating a basic example.

• Introduction
  • Syntax
• Return Type
  • Example
• Conclusion
• FAQs

Introduction

To find the row having the max index value in a dataframe can achieved using the which.max() function. The which.max() function is a function that helps to identify the index of the very first occurrence of the maximum value in a vector or array. This function is defined in the R’s base package.

Syntax

which.max(dataframe_name$columnname) )

Where “$” is utilized to access a particular column of a dataframe. This function evaluates the element to find the max value.

Return Type

This function returns the index of the very first element that contains the maximum value in x.

The which.max() Function works on numeric, character, and logical vectors, and does not handle NA values automatically. To handle this, the ifelse() or na.omit() function needs to be defined explicitly.

To find the maximum values across rows or columns in the data frames or matrices functions like apply() or which() need to be combined with the which.max() function.

Example

# vector 1
data1=c("Alices","John","Mary","Smith","Emily")

# vector 2
data2=c(586,783,379,797,989)

# creating a dataframe with names and salary
final <- data.frame(names=data1,salary=data2)
					
print(final)

# display the maximum value index in a dataframe
print(paste("highest Salary is at index: ",which.max(final$salary)))

Output

[1] “highest Salary is at index:  5”

Conclusion

The which.max() function in R is a simple, efficient, and versatile function to find the index of the first occurrence of the maximum value in an array or vector. This function is mainly used to find the position of the ma value in numeric, character, or logical vectors. If you are interested in learning more about R, then check out our R Programming Course.

FAQs