Return Column Name of Largest Value for Each Row in R DataFrame

In this article, we will discuss how to return column names of the largest value for each row in DataFrame in R Programming Language.

Example:

	Column1	Column2	Column3	Max column
Row1	2	0	0	Column1 , Because,  Column2 value and Column 3 value is less than Column1
Row2	4	3	5	Column3 , Because,  Column2 value and Column 1 value is less than Column3
Row3	10	6	6	Column1 , Because,  Column2 value and Column 3 value is less than Column1
Row4	9	5	4	Column1 , Because,  Column2 value and Column 3 value is less than Column1
Row5	7	9	3	Column2 , Because,  Column1 value and Column 3 value is less than Column2

So For this implementation we will use colnames() and max.col() functions

Syntax:

colnames(dataframe)[max.col(dataframe)]

Here, 

• colnames() is used to get the column names
• max.col() is used to return the maximum column name of the dataframe

Example: R program to get the largest column name in all rows

R

# create  a dataframe with 3 columns and 3 rows
data = data.frame(subject1=c(91, 62, 93),
                  subject2=c(98, 79, 70),
                  subject3=c(100, 78, 98))


# get the largest column name in each row
print(colnames(data)[max.col(data)])

Output:

[1] "subject3" "subject2" "subject3"

Example: R program to get the largest column name in all rows

R

# create  a dataframe with 4 columns and 3 rows
data = data.frame(subject1=c(91, 62, 93, 56, 78),
                  subject2=c(98, 79, 70, 56, 78),
                  subject3=c(100, 78, 98, 56, 71))

# get the largest column name in each row
print(colnames(data)[max.col(data)])

Output:

[1] "subject3" "subject1" "subject3" "subject1" "subject2"