atime: Asymptotic timing

In atime: Asymptotic Timing

Asymptotic timing

Description

Computation time and memory for several R expressions of several different data sizes.

Usage

atime(
N, setup, expr.list=NULL, times=10, seconds.limit=0.01, verbose=FALSE,
result=FALSE, N.env.parent=NULL, ...)

Arguments

N	numeric vector of at least two unique data sizes, default is 2^seq(2,20).
setup	expression to evaluate for every data size, before timings.
expr.list	named list of expressions to time.
times	number of times to evaluate each timed expression.
seconds.limit	if the median timing of any expression exceeds this many seconds, then no timings for larger N are computed.
verbose	logical, print messages after every data size?
result	logical: save the result of evaluating each expression? Or a function to compute a result, given the value obtained after evaluating each expression. If each result is a data frame with one row, then the numeric column names will be saved as more units to analyze (in addition to kilobytes and seconds).
N.env.parent	environment to use as parent of environment created for each data size N, or NULL to use default parent env.
...	named expressions to time.

Details

Each iteration involves first computing the setup expression, and then computing several times the ... expressions. For convenience, expressions may be specified either via code (...) or data (expr.list arg).

Value

list of class atime with elements unit.col.vec (character vector of column names to analyze), seconds.limit (numeric input param), measurements (data table of results).

Author(s)

Toby Dylan Hocking

See Also

atime_grid for avoiding repetition when measuring asymptotic properties of several similar expressions.

Examples

data.table::setDTthreads(1) # for CRAN.

## Polynomial and exponential time string functions.
atime_result_string <- atime::atime(
  seconds.limit=0.001,
  N=unique(as.integer(10^seq(0,3,l=100))),
  setup={
    subject <- paste(rep("a", N), collapse="")
    pattern <- paste(rep(c("a?", "a"), each=N), collapse="")
    linear_size_replacement <- paste(rep("REPLACEMENT", N), collapse="")
  },
  PCRE.match=regexpr(pattern, subject, perl=TRUE),
  TRE.match=regexpr(pattern, subject, perl=FALSE),
  constant.replacement=gsub("a","constant size replacement",subject),
  linear.replacement=gsub("a",linear_size_replacement,subject))
plot(atime_result_string)

atime documentation built on April 12, 2025, 1:12 a.m.