# ranking

##### Windowed rank functions.

Six variations on ranking functions, mimicking 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

```
# NOT RUN {
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))
# }
```

*Documentation reproduced from package dplyr, version 0.7.8, License: MIT + file LICENSE*