Fast Unique Elements / Rows

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).

fduplicated is an alternative to duplicated (or duplicated.data.table, kit::fduplicated).

The collapse versions are versatile and highly competitive.

any_duplicated(x) is faster than any(fduplicated(x)). Note that for atomic vectors, anyDuplicated is currently more efficient if there are duplicates at the beginning of the vector.

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)), for vectors and lists
fduplicated(x, all = FALSE)  # Fast duplicated(x), for vectors and lists
any_duplicated(x)            # Simple logical TRUE|FALSE duplicates check

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.

all

logical. TRUE returns all duplicated values, including the first occurrence.

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.

any_duplicated is currently simply implemented as fnunique(x) < NROW(x), which means it does not have facilities to terminate early, and users are advised to use anyDuplicated with atomic vectors if chances are high that there are duplicates at the beginning of the vector. With no duplicate values or data frames, any_duplicated is considerably faster than anyDuplicated.

Note

These functions treat lists like data frames, unlike unique which has a list method to determine uniqueness of (non-atomic/heterogeneous) elements in a list.

No matrix method is provided. Please use the alternatives provided in package kit with matrices.

Value

funique returns x with duplicate elements/rows removed, fnunique returns an integer giving the number of unique values/rows, fduplicated gives a logical vector with TRUE indicating duplicated elements/rows.

Examples

funique(mtcars$cyl)
#> [1] 6 4 8
funique(gv(mtcars, c(2,8,9)))
#>                   cyl vs am
#> Mazda RX4           6  0  1
#> Datsun 710          4  1  1
#> Hornet 4 Drive      6  1  0
#> Hornet Sportabout   8  0  0
#> Merc 240D           4  1  0
#> Porsche 914-2       4  0  1
#> Ford Pantera L      8  0  1
funique(mtcars, cols = c(2,8,9))
#>                    mpg cyl  disp  hp drat    wt  qsec vs am gear carb
#> Mazda RX4         21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4
#> Datsun 710        22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1
#> Hornet 4 Drive    21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1
#> Hornet Sportabout 18.7   8 360.0 175 3.15 3.440 17.02  0  0    3    2
#> Merc 240D         24.4   4 146.7  62 3.69 3.190 20.00  1  0    4    2
#> Porsche 914-2     26.0   4 120.3  91 4.43 2.140 16.70  0  1    5    2
#>  [ reached 'max' / getOption("max.print") -- omitted 1 rows ]
fnunique(gv(mtcars, c(2,8,9)))
#> [1] 7
fduplicated(gv(mtcars, c(2,8,9)))
#>  [1] FALSE  TRUE FALSE FALSE FALSE  TRUE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE
#> [13]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
#> [25]  TRUE  TRUE FALSE  TRUE FALSE  TRUE  TRUE  TRUE
fduplicated(gv(mtcars, c(2,8,9)), all = TRUE)
#>  [1]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
#> [13]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
#> [25]  TRUE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
any_duplicated(gv(mtcars, c(2,8,9)))
#> [1] TRUE
any_duplicated(mtcars)
#> [1] FALSE