ranking {dplyr} | R Documentation

## 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. Missing values are left as is. If you want to treat them as the smallest or largest values, replace with Inf or -Inf before ranking.
`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, NA)
    row_number(x)
    min_rank(x)
    dense_rank(x)
    percent_rank(x)
    cume_dist(x)

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

    # row_number can be used with single table verbs without specifying x
    # (for data frames and databases that support windowing)
    mutate(mtcars, row_number() == 1L)
    mtcars %>% filter(between(row_number(), 1, 10))

[Package dplyr version 0.7.0 Index]