timed: Record the Computation Time

Description

Saves the result of a calculation as an object of class "timed" which includes information about the time taken to compute the result. The computation time is printed when the object is printed.

Usage

timed(x, ..., starttime = NULL, timetaken = NULL)

Arguments

An expression to be evaluated, or an object that has already been evaluated.

starttime

The time at which the computation is defined to have started. The default is the current time. Ignored if timetaken is given.

timetaken

The length of time taken to perform the computation. The default is the time taken to evaluate x.

…

Ignored.

Value

An object inheriting the class "timed".

Details

This is a simple mechanism for recording how long it takes to perform complicated calculations (usually for the purposes of reporting in a publication).

If x is an expression to be evaluated, timed(x) evaluates the expression and measures the time taken to evaluate it. The result is saved as an object of the class "timed". Printing this object displays the computation time.

If x is an object which has already been computed, then the time taken to compute the object can be specified either directly by the argument timetaken, or indirectly by the argument starttime.

timetaken is the duration of time taken to perform the computation. It should be the difference of two clock times returned by proc.time. Typically the user sets begin <- proc.time() before commencing the calculations, then end <- proc.time() after completing the calculations, and then sets timetaken <- end - begin.
starttime is the clock time at which the computation started. It should be a value that was returned by proc.time at some earlier time when the calculations commenced. When timed is called, the computation time will be taken as the difference between the current clock time and starttime. Typically the user sets begin <- proc.time() before commencing the calculations, and when the calculations are completed, the user calls result <- timed(result, starttime=begin).

If the result of evaluating x belongs to other S3 classes, then the result of timed(x, …) also inherits these classes, and printing the object will display the appropriate information for these classes as well.

Examples

Run this code

# NOT RUN {
  timed(clarkevans(cells))

  timed(Kest(cells))

  answer <- timed(42, timetaken=4.1e17)
  answer
# }