You can use the following syntax in R to count the number of occurrences of certain values in columns of a data frame:

#count number of occurrences of each value in column table(df$column_name) #count number of occurrences of each value (including NA values) in column table(df$column_name, useNA = 'always') #count number of occurrences of specific value length(which(df$column_name==value))

The following examples show how to use this syntax in practice with the following data frame:

#create data frame df <- data.frame(player=c('A', 'B', 'C', 'D', 'E', 'F'), team=c('Mavs', 'Mavs', 'Suns', 'Nets', 'Nets', 'Nets'), points=c(20, 22, 26, 30, 30, NA)) #view data frame df player team points 1 A Mavs 20 2 B Mavs 22 3 C Suns 26 4 D Nets 30 5 E Nets 30 6 F Nets NA

**Example 1: Count Occurrences of Values in Column**

The following code shows how to count the number of occurrences of each value in the ‘team’ column:

#count number of occurrences of each team table(df$team) Mavs Nets Suns 2 3 1

This tells us:

- The team name ‘Mavs’ appears 2 times.
- The team name ‘Nets’ appears 3 times.
- The team name ‘Suns’ appears 1 time.

**Example 2: Count Occurrences of Values in Column (Including NA Values)**

The following code shows how to count the number of occurrences of each value (including NA values) in the ‘points’ column:

#count number of occurrences of each value in 'points', including NA occurrences table(df$points, useNA = 'always') 20 22 26 30 <NA> 1 1 1 2 1

This tells us:

- The value 20 appears 1 time.
- The value 22 appears 1 time.
- The value 26 appears 1 time.
- The value 30 appears 2 times.
- The value NA (missing value) appears 1 time.

**Example 3: Count Occurrences of Specific Value in Column**

The following code shows how to count the number of occurrences of the value 30 in the ‘points’ column:

#count number of occurrences of the value 30 in 'points' column length(which(df$points == 30)) [1] 2

This tells us that the value 30 appears 2 times in the ‘points’ column.

You can also use the following syntax to count the number of occurrences of several different values in the ‘points’ column:

#count number of occurrences of the value 30 or 26 in 'points' column length(which(df$points == 30 | df$points == 26)) [1] 3

This tells us that the value 30 or 26 appear a total of 3 times in the ‘points’ column.

**Additional Resources**

How to Sum Specific Columns in R

How to Calculate the Mean of Multiple Columns in R

How to Find the Max Value Across Multiple Columns in R