Often you may be interested in only counting the number of rows in an R data frame that meet some criteria. Fortunately this is easy to do using the following basic syntax:
sum(df$column == value, na.rm=TRUE)
The following examples show how to use this syntax in practice on the following data frame:
#create data frame
data #view data frame
data
team points rebounds
1 Mavs 14 8
2 Mavs NA 5
3 Spurs 8 5
4 Spurs 17 9
5 Lakers 22 12
Example 1: Count Rows Equal to Some Value
The following code shows how to count the number of rows where the team name is equal to “Mavs”:
sum(data$team == 'Mavs')
[1] 2
The following code shows how to count the number of rows where the team name is equal to “Mavs” or “Lakers”:
sum(data$team == 'Mavs' | data$team == 'Lakers') [1] 3
The following code shows how to count the number of rows where the team name is not equal to “Lakers”:
sum(data$team != 'Lakers')
[1] 4 Example 2: Count Rows Greater or Equal to Some Value
The following code shows how to count the number of rows where points is greater than 10:
sum(data$points > 10, na.rm=TRUE)
[1] 3 The following code shows how to count the number of rows where rebounds is less than or equal to 9:
sum(data$rebounds TRUE) [1] 4
Example 3: Count Rows Between Two Values
The following code shows how to count the number of rows where points is between 10 and 20:
sum(data$points > 10 & data$points TRUE) [1] 2
The following code shows how to count the number of rows where rebounds is between 8 and 10:
sum(data$rebounds > 8 & data$rebounds TRUE) [1] 1
Additional Resources
How to Count Observations by Group in R
How to Group & Summarize Data in R