Locate sorted groups

vec_locate_sorted_groups() returns a data frame containing a key column with sorted unique groups, and a loc column with the locations of each group in x. It is similar to vec_group_loc(), except the groups are returned sorted rather than by first appearance.

Usage

vec_locate_sorted_groups(
  x,
  ...,
  direction = "asc",
  na_value = "largest",
  nan_distinct = FALSE,
  chr_proxy_collate = NULL
)

Arguments

x

A vector

...

These dots are for future extensions and must be empty.

direction

Direction to sort in.

• A single "asc" or "desc" for ascending or descending order respectively.

• For data frames, a length 1 or ncol(x) character vector containing only "asc" or "desc", specifying the direction for each column.

na_value

Ordering of missing values.

• A single "largest" or "smallest" for ordering missing values as the largest or smallest values respectively.

• For data frames, a length 1 or ncol(x) character vector containing only "largest" or "smallest", specifying how missing values should be ordered within each column.

nan_distinct

A single logical specifying whether or not NaN should be considered distinct from NA for double and complex vectors. If TRUE, NaN will always be ordered between NA and non-missing numbers.

chr_proxy_collate

A function generating an alternate representation of character vectors to use for collation, often used for locale-aware ordering.

• If NULL, no transformation is done.

• Otherwise, this must be a function of one argument. If the input contains a character vector, it will be passed to this function after it has been translated to UTF-8. This function should return a character vector with the same length as the input. The result should sort as expected in the C-locale, regardless of encoding.

For data frames, chr_proxy_collate will be applied to all character columns.

Common transformation functions include: tolower() for case-insensitive ordering and stringi::stri_sort_key() for locale-aware ordering.

Value

A two column data frame with size equal to vec_size(vec_unique(x)).

• A key column of type vec_ptype(x).

• A loc column of type list, with elements of type integer.

Details

vec_locate_sorted_groups(x) is equivalent to, but faster than:

info <- vec_group_loc(x)
vec_slice(info, vec_order(info$key))

Dependencies of vec_locate_sorted_groups()

• vec_proxy_order()

Examples

df <- data.frame(
  g = sample(2, 10, replace = TRUE),
  x = c(NA, sample(5, 9, replace = TRUE))
)

# `vec_locate_sorted_groups()` is similar to `vec_group_loc()`, except keys
# are returned ordered rather than by first appearance.
vec_locate_sorted_groups(df)
#>   key.g key.x   loc
#> 1     1     2     8
#> 2     1     3     9
#> 3     1     4 3, 10
#> 4     1     5     5
#> 5     1    NA     1
#> 6     2     1  6, 7
#> 7     2     2     4
#> 8     2     5     2

vec_group_loc(df)
#>   key.g key.x   loc
#> 1     1    NA     1
#> 2     2     5     2
#> 3     1     4 3, 10
#> 4     2     2     4
#> 5     1     5     5
#> 6     2     1  6, 7
#> 7     1     2     8
#> 8     1     3     9