Get first n rows & last n rows – head(), tail(), slice(),top_n() function in R

In This tutorial we will learn about head and tail function in R. head() function in R takes argument “n” and returns the first n rows of a dataframe or matrix, by default it returns first 6 rows. tail() function  in R returns last n rows of a dataframe or matrix, by default it returns last 6 rows. we can also use slice() group of functions in dplyr package like slice_sample(),slice_head(), slice_tail(), slice_min() and slice_max() function to get n rows. top_n() function can also be used for same. Lets see an example of

• Head Function in R: returns the first n rows of a matrix or data frame in R
• Tail Function in R: returns the last n rows of a matrix or data frame in R
• slice_sample() function in R returns the sample n rows of the dataframe in R
• slice_max() function in R returns the maximum n rows of the dataframe in R
• slice_min() function in R returns the minimum n rows of the dataframe in R
• First n rows is returned using slice_head() function in R
• Last n rows is returned using slice_tail() function in R
• top_n() function in R returns the top n rows based on a specific column.

Syntax for head function in R:

• df – Data frame
• n – number of rows

Example of head function in R:

Lets use mtcars table to demonstrate head function in R

```# head function in R

```

By default head function in R returns first 6 rows of a data frame or matrix so the output will be

Example of head function in R with Specified rows:

```# head function in R with specified rows

```

head function in R returns first 2 rows of a data frame or matrix so the output will be

head() function to extract first n values of a column :

head() function takes up the column name and number of values to be extracted as argument as show below.

```

# head function in R to get first n values of the column

```

so the first n values of the mpg column is extracted as shown below.

[1] 21.0 21.0 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2

Syntax for tail function in R:

tail(df)
tail(df,n=number)
• df – Data frame
• n – number of rows

Example of tail function in R:

Lets use mtcars table to demonstrate tail function in R

```# tail function in R

tail(mtcars)
```

By default tail function in R returns last 6 rows of a data frame or matrix so the output will be

Example of tail function in R with Specified rows:

```# tail function in R with specified rows

tail(mtcars, n=2)
```

tail function in R returns last 2 rows of a data frame or matrix so the output will be

tail() function to extract last n values of a column :

tail() function takes up the column name and number of values to be extracted as argument as show below.

```

# tail function in R to get first n values of the column
tail(mtcars\$mpg, n=10)
```

so the last n values of the mpg column is extracted as shown below.

[1] 15.2 13.3 19.2 27.3 26.0 30.4 15.8 19.7 15.0 21.4

Slice Family of function in R dplyr :

slice_head() function returns the top n rows of the dataframe as shown below.

```
library(dplyr)

```

so the top 5 rows are returned

slice_tail() function in R

slice_tail() function returns the bottom n rows of the dataframe as shown below.

```
# slice_tail() function in R
library(dplyr)
mtcars %>% slice_tail(n = 5)

```

so the sample 5 rows are returned

slice_max() function in R

slice_max() function returns the maximum n rows of the dataframe based on a column as shown below.

```
# slice_max() function in R
library(dplyr)
mtcars %>% slice_max(mpg, n = 5)
```

so the max 5 rows based on mpg column will be returned

slice_min() function in R

slice_min() function returns the minimum n rows of the dataframe based on a column as shown below.

```
# slice_min() function in R

library(dplyr)
mtcars %>% slice_min(mpg, n = 5)
```

so the min 5 rows based on mpg column will be returned

slice_sample() function in R

slice_sample() function returns the sample n rows of the dataframe as shown below.

```
# slice_sample() function in R

library(dplyr)
mtcars %>% slice_sample(n = 5)

```

so the sample 5 rows are returned

Slice by Group in R

slice_head() by group in R:  returns the top n rows of the group using slice_head() and group_by() functions

```

# slice_head() by group in R
mtcars %>% group_by(vs) %>% slice_head(n = 2)

```

slice_tail() by group in R:  returns the bottom n rows of the group using slice_tail() and group_by() functions

```

# slice_tail() by group in R
mtcars %>% group_by(vs) %>% slice_tail(n = 2)

```

slice_sample() by group in R:  returns the sample n rows of the group using slice_sample() and group_by() functions

```

# slice_sample() by group in R
mtcars %>% group_by(vs) %>% slice_sample(n = 2)

```

Using top_n() function in R:

Top n rows of the dataframe with respect to a column is achieved by using top_n() functions

```

# top_n() function in R

mtcars %>% top_n(10)
```

so the resultant dataframe will be

for more details refer here