dplyr (version 0.2)

top_n: Select top n rows (by value).

Description

This is a convenient wrapper that uses filter and rank to select the top n entries in each group, ordered by wt.

Usage

top_n(x, n, wt = NULL)

Arguments

x

a tbl to filter

n

number of rows to return. If x is grouped, this is the number of rows per group. May include more than n if there are ties.

wt

the variable to use for ordering. If not specified, defaults to the last variable in the tbl.

Examples

data("Batting", package = "Lahman")
players <- group_by(tbl_df(Batting), playerID)
games <- tally(players, G)
top_n(games, 10, n)

# A little nicer with %>%
tbl_df(Batting) %>% group_by(playerID) %>% tally(G) %>% top_n(10)