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In R, the first N rows of a data frame can be selected using the head() function, which takes the number of rows as an argument and returns the first N rows of the data frame. For example, head(df,3) will return the first 3 rows of df. Additionally, if you want to select a subset of rows from a data frame, you can use the subset() function, which takes a logical expression as an argument and returns a subset of the data frame based on the expression. Finally, you can also use the slice() function to select a range of rows from a data frame, by specifying the start and end rows as arguments.
You can use one of the following methods to select the first N rows of a data frame in R:
Method 1: Use head() from Base R
head(df, 3)
Method 2: Use indexing from Base R
df[1:3, ]
Method 3: Use slice() from dplyr
library(dplyr)
df %>% slice(1:3) 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', 'B', 'C', 'D', 'E', 'F', 'G'), points=c(99, 90, 86, 88, 95, 99, 91), assists=c(33, 28, 31, 39, 34, 35, 40)) #view data frame df team points assists 1 A 99 33 2 B 90 28 3 C 86 31 4 D 88 39 5 E 95 34 6 F 99 35 7 G 91 40
Example 1: Use head() from Base R
One way to select the first N rows of a data frame is by using the head() function from base R:
#select first 3 rows of data frame
head(df, 3)
team points assists
1 A 99 33
2 B 90 28
3 C 86 31 If you use the head() function without any numerical argument, R will automatically select the first 6 rows of the data frame:
#select first 6 rows of data frame
head(df)
team points assists
1 A 99 33
2 B 90 28
3 C 86 31
4 D 88 39
5 E 95 34
6 F 99 35
Example 2: Use indexing from Base R
Another way to select the first N rows of a data frame is by using indexing syntax from base R:
#select first 3 rows of data frame
df[1:3, ]
team points assists
1 A 99 33
2 B 90 28
3 C 86 31 #select first 3 rows of 'team' and 'points' columns only
df[1:3, c('team', 'points')]
team points
1 A 99
2 B 90
3 C 86 Example 3: Use slice() from dplyr
Another way to select the first N rows of a data frame is by using the slice() function from the package:
library(dplyr)
#select first 3 rows of data frame
df %>% slice(1:3)
team points assists
1 A 99 33
2 B 90 28
3 C 86 31 Related:
The following tutorials explain how to perform other common tasks in R: