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You can use the following methods to count the number of unique values in a column of a data frame in R:

**Method 1: Using Base R**

length(unique(df$my_column))

**Method 2: Using dplyr**

library(dplyr) n_distinct(df$my_column)

The following examples show how to use each method in practice with the following data frame:

#create data frame df frame(team=c('A', 'A', 'A', 'A', 'B', 'B', 'C', 'C', 'D'), points=c(10, 13, 14, 14, 18, 19, 20, 20, 22)) #view data frame df team points 1 A 10 2 A 13 3 A 14 4 A 14 5 B 18 6 B 19 7 C 20 8 C 20 9 D 22

**Method 1: Count Unique Values in Column Using Base R**

The following code shows how to count the number of unique values in the **points** column of the data frame using functions from base R:

#count unique values in points column length(unique(df$points)) [1] 7

There are 7 unique value in the **points** column.

To count the number of unique values in each column of the data frame, we can use the **sapply()** function:

#count unique values in each column sapply(df, function(x) length(unique(x))) team points 4 7

From the output we can see:

- There are 7 unique values in the
**points**column. - There are 4 unique values in the
**team**columm.

**Method 2: ****Count Unique Values in Column Using dplyr**

The following code shows how to count the number of distinct values in the **points **column using the **n_distinct()** function from the dplyr package:

library(dplyr) #count unique values in points column n_distinct(df$points) [1] 7

There are 7 unique value in the **points** column.

To count the number of unique values in each column of the data frame, we can use the **sapply()** function:

library(dplyr) #count unique values in each column sapply(df, function(x) n_distinct(x)) team points 4 7

From the output we can see:

- There are 7 unique values in the
**points**column. - There are 4 unique values in the
**team**columm.

Notice that these results match the ones from the base R method.

**Additional Resources**

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

How to Count Duplicates in R

How to Count Unique Values by Group in R

How to Count Number of NA Values in Each Column in R