Select top (or bottom) n rows (by value)

top_n() has been superseded in favour of slice_min()/slice_max(). While it will not be deprecated in the near future, retirement means that we will only perform critical bug fixes, so we recommend moving to the newer alternatives.

top_n() was superseded because the name was fundamentally confusing as it returned what you might reasonably consider to be the bottom rows. Additionally, the wt variable had a confusing name, and strange default (the last column in the data frame). Unfortunately we could not see an easy way to fix the existing top_n() function without breaking existing code, so we created a new alternative.

Usage

top_n(x, n, wt)

top_frac(x, n, wt)

Arguments

x

A data frame.

n

Number of rows to return for top_n(), fraction of rows to return for top_frac(). If n is positive, selects the top rows. If negative, selects the bottom rows. If x is grouped, this is the number (or fraction) of rows per group. Will include more rows if there are ties.

wt

(Optional). The variable to use for ordering. If not specified, defaults to the last variable in the tbl.

Examples

df <- data.frame(x = c(6, 4, 1, 10, 3, 1, 1))

df %>% top_n(2)  # highest values
#> Selecting by x
#>    x
#> 1  6
#> 2 10
df %>% top_n(-2) # lowest values
#> Selecting by x
#>   x
#> 1 1
#> 2 1
#> 3 1
# now use
df %>% slice_max(x, n = 2)
#>    x
#> 1 10
#> 2  6
df %>% slice_min(x, n = 2)
#>   x
#> 1 1
#> 2 1
#> 3 1

# top_frac() -> prop argument of slice_min()/slice_max()
df %>% top_frac(.5)
#> Selecting by x
#>    x
#> 1  6
#> 2  4
#> 3 10
# ->
df %>% slice_max(x, prop = 0.5)
#>    x
#> 1 10
#> 2  6
#> 3  4