Get the Minimum 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 minimum value in a column of an R dataframe.

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

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

The following is the syntax –

min(dataframe[[column_name]])

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

It returns the minimum value in the passed column.

Steps to calculate the minimum value in an R column

Let’s now look at a step-by-step example of using the above syntax to compute the min 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 minimum in a column using the min() function

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

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

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

Output:

[1] 65000

The minimum value in the “Salary” column is 65000.

Minimum 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 min() function to get the minimum value in the “Salary” column.

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

Output:

[1] NA

We get NA as the min 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 min value in a column with NA values, pass na.rm=TRUE to the min() function which essentially skips these values when computing the minimum.

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

Output:

[1] 72000

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

Summary – Minimum Value in an R Column

In this tutorial, we looked at how to compute the minimum 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 min() function to compute the minimum 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 min() function to calculate the minimum excluding the NA values in the column.

You might also be interested in –

• How to Add a Column to a Dataframe in R?
• Rename Column Name in R Dataframe
• Select One or More Columns From R Dataframe