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In R, you can select rows by their index using the square bracket notation. You can specify the index by either using a single number to select a single row, a range of numbers to select a set of rows, or a logical vector to select a set of rows that meet certain criteria. Examples of each technique are provided to demonstrate how to use the index to select rows in R.
You can use the following methods to select rows from a data frame by index in R:
Method 1: Select One Row by Index
#select third row
df[3,]
Method 2: Select Multiple Rows by Index
#select third, fourth, and sixth rows
df[c(3, 4, 6),]
Method 3: Select Range of Rows by Index
#select rows 2 through 5
df[2:5,]
The following examples show how to use each method in practice with the following data frame:
#create data frame df <- data.frame(team=c('A', 'A', 'A', 'B', 'B', 'B'), points=c(19, 14, 14, 29, 25, 30), assists=c(4, 5, 5, 4, 12, 10), rebounds=c(9, 7, 7, 6, 10, 11)) #view data frame df team points assists rebounds 1 A 19 4 9 2 A 14 5 7 3 A 14 5 7 4 B 29 4 6 5 B 25 12 10 6 B 30 10 11
Example 1: Select One Row by Index
The following code shows how to select only the third row in the data frame:
#select third row
df[3, ]
team points assists rebounds
3 A 14 5 7
Only the values from the third row are returned.
Example 2: Select Multiple Rows by Index
The following code shows how to select multiple rows by index in the data frame:
#select third, fourth, and sixth rows
df[c(3, 4, 6), ]
team points assists rebounds
3 A 14 5 7
4 B 29 4 6
6 B 30 10 11
Only the values from the third, fourth, and sixth rows are returned.
Example 3: Select Range of Rows by Index
The following code shows how to select rows 2 through 5 in the data frame:
#select rows 2 through 5
df[2:5, ]
team points assists rebounds
2 A 14 5 7
3 A 14 5 7
4 B 29 4 6
5 B 25 12 10
All values for rows 2 through 5 are returned.
The following tutorials explain how to perform other common tasks in R: