Parallel Sort

Similar to base::sort, but only for character vectors and partly using parallelism. It is experimental and might change in the future. Use with caution.

Usage

psort(x, decreasing=FALSE, na.last=NA,
      nThread=getOption("kit.nThread"),c.locale=TRUE)

Arguments

x

A character vector. For other input, psort() warns and calls base::sort().

na.last

Controls the treatment of NAs. If TRUE, missing values are put last; if FALSE, they are put first; if NA, they are removed.

decreasing

Logical. If TRUE, sort in decreasing order. Default is FALSE.

nThread

Integer. Number of threads to use. Default is getOption("kit.nThread").

c.locale

Logical. If TRUE (default), sort byte by byte in the C locale. The result is the same on every operating system and matches sort(x, method = "radix"). If FALSE, use the session locale and sort(x, method = "quick"); the order of accented letters and other non-ASCII text can differ between operating systems and locales.

Details

For non-character x, psort() warns and calls base::sort() with method = "radix" when c.locale = TRUE, and method = "quick" otherwise.

Value

A character vector with the values of x in sorted order.

Author

Morgan Jacob

Examples

x = c("b","A","B","a","\xe4")
Encoding(x) = "latin1"
identical(psort(x, c.locale=FALSE), sort(x))
#> [1] TRUE
identical(psort(x, c.locale=TRUE), sort(x, method="radix"))
#> [1] TRUE

# Benchmarks
# ----------
# strings = as.character(as.hexmode(1:1000))
# x = sample(strings, 1e8, replace=TRUE)
# system.time({kit::psort(x, na.last = TRUE, nThread = 1L)})
#   user  system elapsed
#  2.833   0.434   3.277
# system.time({sort(x,method="radix",na.last = TRUE)})
#   user  system elapsed
#  5.597   0.559   6.176
# system.time({x[order(x,method="radix",na.last = TRUE)]})
#   user  system elapsed
#  5.561   0.563   6.143