funique {collapse}R Documentation

Fast Unique Elements / Rows

Description

funique is an efficient alternative to unique (or unique.data.table, kit::funique, dplyr::distinct).

fnunique is an alternative to NROW(unique(x)) (or data.table::uniqueN, kit::uniqLen, dplyr::n_distinct).

The collapse versions are versatile and highly competitive.

Usage

funique(x, ...)

## Default S3 method:
funique(x, sort = FALSE, method = "auto", ...)

## S3 method for class 'data.frame'
funique(x, cols = NULL, sort = FALSE, method = "auto", ...)

## S3 method for class 'sf'
funique(x, cols = NULL, sort = FALSE, method = "auto", ...)

# Methods for indexed data / compatibility with plm:

## S3 method for class 'pseries'
funique(x, sort = FALSE, method = "auto", drop.index.levels = "id", ...)

## S3 method for class 'pdata.frame'
funique(x, cols = NULL, sort = FALSE, method = "auto", drop.index.levels = "id", ...)


fnunique(x) # Fast NROW(unique(x))

Arguments

x

a atomic vector or data frame / list of equal-length columns.

sort

logical. TRUE orders the unique elements / rows. FALSE returns unique values in order of first occurrence.

method

an integer or character string specifying the method of computation:

Int. String Description
1 "auto" automatic selection: hash if sort = FALSE else radix.
2 "radix" use radix ordering to determine unique values. Supports sort = FALSE but only for character data.
3 "hash" use index hashing to determine unique values. Supports sort = TRUE but only for atomic vectors (default method).
cols

compute unique rows according to a subset of columns. Columns can be selected using column names, indices, a logical vector or a selector function (e.g. is.character). Note: All columns are returned.

...

arguments passed to radixorderv, e.g. decreasing or na.last. Only applicable if method = "radix".

drop.index.levels

character. Either "id", "time", "all" or "none". See indexing.

Details

If all values/rows are already unique, then x is returned. Otherwise a copy of x with duplicate rows removed is returned. See group for some additional computational details.

The sf method simply ignores the geometry column when determining unique values.

Methods for indexed data also subset the index accordingly.

Value

x with duplicate elements/rows removed.

Note

No matrix method is provided. Please see kit::funique for a fast alternative with a matrix method.

See Also

fndistinct, group, Fast Grouping and Ordering, Collapse Overview.

Examples

funique(mtcars$cyl)
funique(gv(mtcars, c(2,8,9)))
funique(mtcars, cols = c(2,8,9))
fnunique(gv(mtcars, c(2,8,9)))
[Package collapse version 1.8.6 Index]