dplyr (version 0.2)

ranking: Windowed rank functions.

Description

Six variations on ranking functions, mimicing the ranking functions described in SQL2003. They are currently implemented using the built in rank function, and are provided mainly as a convenience when converting between R and SQL. All ranking functions map smallest inputs to smallest outputs. Use desc to reverse the direction..

Usage

row_number(x)
ntile(x, n)
min_rank(x)
dense_rank(x)
percent_rank(x)
cume_dist(x)

Arguments

x

a vector of values to rank

n

number of groups to split up into.

Details

• row_number: equivalent to rank(ties.method = "first")

• min_rank: equivalent to rank(ties.method = "min")

• dense_rank: like min_rank, but with no gaps between ranks

• percent_rank: a number between 0 and 1 computed by rescaling min_rank to [0, 1]

• cume_dist: a cumulative distribution function. Proportion of all values less than or equal to the current rank.

• ntile: a rough rank, which breaks the input vector into n buckets.

Examples

x <- c(5, 1, 3, 2, 2)
row_number(x)
min_rank(x)
dense_rank(x)
percent_rank(x)
cume_dist(x)

ntile(x, 2)
ntile(runif(100), 10)