Get the Maximum Value in an R Column

The R programming language comes with a number of helpful functions to work with the data stored in data structures like vectors, lists, dataframes, etc. In this tutorial, we will look at one such function that helps us get the maximum value in a column of an R dataframe.

How to get the max value in an R dataframe column?

You can use the built-in max() function in R to compute the maximum value in a dataframe column. Pass the column values as an argument to the function.

The following is the syntax –

max(dataframe[[column_name]])

Pass na.rm=TRUE to avoid the NA values when computing the maximum.

It returns the maximum value in the passed column.

Steps to calculate the maximum value in an R column

Let’s now look at a step-by-step example of using the above syntax to compute the max value of a numeric column in R.

Step 1 – Create a dataframe

First, we will create an R dataframe that we will be using throughout this tutorial.

# create a dataframe
employees_df = data.frame(
  "Name"= c("Jim", "Dwight", "Angela", "Tobi", "Kevin"),
  "Age"= c(26, 28, 29, 32, 30),
  "Department"= c("Sales", "Sales", "Accounting", "HR", "Accounting"),
  "Salary" = c(80000, 81000, 72000, 65000, 72000)
)
# display the dataframe
print(employees_df)

Output:

    Name Age Department Salary
1    Jim  26      Sales  80000
2 Dwight  28      Sales  81000
3 Angela  29 Accounting  72000
4   Tobi  32         HR  65000
5  Kevin  30 Accounting  72000

We now have a dataframe containing information about some employees in an office. The dataframe has the columns – “Name”, “Age”, “Department”, and “Salary”.

Step 2 – Calculate the maximum in a column using the max() function

To calculate the maximum value in a column, pass the column values as an argument to the max() function. You can use the [[]] notation to access the values of a column.

Let’s compute the maximum salary from the above data. That is, we want to know the max value in the “Salary” column.

# max value in "Salary" column
max_salary = max(employees_df[["Salary"]])
# display the max salary
print(max_salary)

Output:

[1] 81000

The maximum value in the “Salary” column is 81000.

Maximum value of a column with NA values in R

What if there are NA values in a column?

Let’s find out.

# create a dataframe
employees_df = data.frame(
  "Name"= c("Jim", "Dwight", "Angela", "Tobi", "Kevin"),
  "Age"= c(26, 28, 29, 32, 30),
  "Department"= c("Sales", "Sales", "Accounting", "HR", "Accounting"),
  "Salary" = c(80000, 81000, 72000, NA, 72000)
)
# display the dataframe
print(employees_df)

Output:

    Name Age Department Salary
1    Jim  26      Sales  80000
2 Dwight  28      Sales  81000
3 Angela  29 Accounting  72000
4   Tobi  32         HR     NA
5  Kevin  30 Accounting  72000

Here, we created a new dataframe such that the “Salary” column contains some NA values.

Now, let’s apply the max() function to get the maximum value in the “Salary” column.

# max value in "Salary" column
max_salary = max(employees_df[["Salary"]])
# display the max salary
print(max_salary)

Output:

[1] NA

We get NA as the max value. This happened because the “Salary” column here contains NA values and performing any mathematical operation with NA results in an NA in R.

If you want to compute the max value in a column with NA values, pass na.rm=TRUE to the max() function which essentially skips these values when computing the maximum.

# max value in "Salary" column
max_salary = max(employees_df[["Salary"]], na.rm=TRUE)
# display the max salary
print(max_salary)

Output:

[1] 81000

We now get the max value in the “Salary” column excluding the NA values.

Summary – Maximum Value in an R Column

In this tutorial, we looked at how to compute the maximum value in a column of an R dataframe. The following is a short summary of the steps –

1. Create a dataframe (skip this step if you already have a dataframe on which you want to operate).
2. Use the max() function to compute the maximum value in the column. Pass the column vector as an argument.
3. If your column contains any NA values, pass na.rm=TRUE to the max() function to calculate the maximum excluding the NA values in the column.

You might also be interested in –

• How to Add a Column to a Dataframe in R?
• Sum of Values in an R Column
• R – Count Unique Values in Dataframe Column