atime (version 2025.4.1)

atime: 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, ...)

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).

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.

Author

Toby Dylan Hocking

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).

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)