Profiling code in R

Overview

Profiling in R can be performed using the following two functions:

  1. Rprof
  2. summaryRprof

The Rprof function

The Rprof function records the call stack to the specified file every interval of seconds. It is also used to start and stop the profiling operation.

Syntax

Rprof(filename = "Rprof.out", append = FALSE, interval = 0.02)

Parameters

  • filename: This is a file to be used for recording the profiling information.
  • append: This is a boolean field that indicates whether the profiling information is appended to the existing file or be overwritten.
  • interval: The time elapsed between the two consecutive samples. The default value is 20 milliseconds.

The summaryRprof function

The summaryRprof function is used to summarize the information given by the Rprof function.

Syntax

summaryRprof(filename = "Rprof.out")

Parameter

  • filename: This is a Rprof function output file.

Return value

The function returns the following summary statistics:

Metric Description
by.self A DataFrame of time spent in the executing function alone
by.total A DataFrame of total time spent in the function and its callees
sample.interval The sampling time interval (Refer interval parameter of Rprof function)
sampling.time The total time spent in profiling the run

Code example

Let’s look at the code below:

Rprof(tmp <- tempfile())
n = 15
if(n<=0){
    print("Invalid n value")
}else{
    fibo_list <- numeric(n)
    fibo_list[1] <- 1
    fibo_list[2] <- 1
    print(paste("The first",n," fibonacci numbers are as follows:"))
    if(n == 1) print(fibo_list[1])
    else if(n == 2) print(fibo_list)
    else{
        for (i in 3:10) fibo_list[i] <- fibo_list[i - 1] + fibo_list[i - 2]
        print(fibo_list)
    }
}
Rprof(NULL)
summaryRprof(tmp)

Code explanation

  • Line 1: We invoke the Rprof() function with a temporary file.
  • Lines 2-16: We have defined the logic for finding the first n numbers in the Fibonacci sequence.
  • Line 17: We stop the profiling by invoking Rprof(NULL).
  • Line 18: We obtain he profiling summary by invoking the summaryRprof() function.

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