You can use the following syntax to find the column with the max value for each row in a data frame in R:

df$max_col <- colnames(df)[max.col(df, ties.method='first')]

Note that the argument **ties.method=’first’** specifies that the first max column should be returned if there are multiple columns with a max value in a given row.

Other values you can provide to this argument include **random** and **last**, if you’d like to return a random max column or the last max column instead.

The following example shows how to use this syntax in practice.

**Example: Find Column with Max Value for Each Row in R**

Suppose we have the following data frame in R that contains information about the number of points scored by six different basketball players during three games:

**#create data frame
df <- data.frame(game1=c(23, 20, 14, 12, 19, 15),
game2=c(9, 10, 11, 13, 13, 15),
game3=c(29, 11, 22, 19, 14, 15))
#view data frame
df
game1 game2 game3
1 23 9 29
2 20 10 11
3 14 11 22
4 12 13 19
5 19 13 14
6 15 15 15**

Suppose we would like to create a new column that contains the name of the column with the max value in each row of the data frame.

We can use the following syntax to do so:

**#create new column that contains column with max value for each row
df$max_col <- colnames(df)[max.col(df, ties.method='first')]
#view updated data frame
df
game1 game2 game3 max_col
1 23 9 29 game3
2 20 10 11 game1
3 14 11 22 game3
4 12 13 19 game3
5 19 13 14 game1
6 15 15 15 game1
**

The new column called **max_col** contains the name of the column with the max value in each row.

For example:

- In the first row,
**game3**contained the max value. - In the second row,
**game1**contained the max value. - In the third row,
**game3**contained the max value.

And so on.

Note that each column in the last row has the same value.

Since we specified **ties.method=’first’** in the** max.col()** function, the code returned **game1** as the column with the max value since this is the first max column.

**Additional Resources**

The following tutorials explain how to perform other common operations in R:

R: How to Find Unique Rows Across Multiple Columns

R: How to Find Columns with All Missing Values

R: How to Find Unique Values in a Column