A dataframe in R is a data structure used to store tabular data in rows and columns. In this tutorial, we will look at how to count the unique values in a column of an R dataframe with the help of some examples.
How do you get the unique values count of an R dataframe column?
You can use a combination of the
length() function and the
unique() function in R to get the count of unique values in a dataframe column.
The idea is to first get the unique values from the column in a vector using the
unique() function and then apply
length() function on this unique values vector to get a count of the unique values in the column.
The following is the syntax –
We get the unique values count in the column as an integer.
Steps to count distinct values in an R dataframe column
Let’s now look at the steps to follow to get distinct values in a dataframe column in R
Step 1 – Create a dataframe
First, we will create a 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") ) # display the dataframe print(employees_df)
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Name Age Department 1 Jim 26 Sales 2 Dwight 28 Sales 3 Angela 29 Accounting 4 Tobi 32 HR 5 Kevin 30 Accounting
We now have a dataframe containing information about some employees working in an office. The dataframe has columns “Name”, “Age”, and “Department”.
Step 2 – Get the count of the unique values in the column using
To get the unique value count in a column, pass the column values vector to the
unique() function as an argument. You can use the
[] notation to get a column’s values vector. This will result in a vector of unique values from the column.
Then, you can then apply the
length() function on this vector of unique values to get the unique values count.
Let’s get the count of distinct departments from the “Department” column in the above dataframe.
# get count of distinct values in "Department" column dept_count <- length(unique(employees_df[["Department"]])) # display the result print(dept_count)
We get the number of unique values in the “Department” column as 3.
Note that you can also use the column index to access a column’s values. For example, in the above dataframe, the index of the “Department” column is 3 (rows and columns in R are indexed starting from 1).
# get count of distinct values in "Department" column dept_count <- length(unique(employees_df[])) # display the result print(dept_count)
We get the same result as above.
In this tutorial, we looked at how to count the unique values in the column in an R dataframe. The following is a short summary of the steps –
- Create a dataframe (skip this step if you already have a dataframe on which you want to operate).
- Use a combination of the
length()functions in R to count the unique values in a column.
You might also be interested in –
- Create a DataFrame in R
- How to Add a Row to a Dataframe in R?
- How to Add a Column to a Dataframe in R?
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