timer: allow organized tracking of R code execution time

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allow organized tracking of R code execution time

Description

The 'timer' function allows you to append timeStamps to a data.table, and include additional metadata provided as arguments. The last call calculates time differences between timeStamps.

Usage

timer(timer_table = data.table(), end = FALSE, ...)

Arguments

timer_table	A data.table containing the timer log to continue from. Defaults to an empty 'data.table().
end	A logical, inidicating the end of the timer, defaulted to FALSE. 'timer()' calls must be placed at the beginning of each part : therefore, this 'closing' step is necessary to compute time for the last part. Time differences between timeStamps are calculated only when closing the timer.
...	Additional specifications. Use named arguments to provide documentation on the code parts you are timing : naming the current step, the version of the code you are trying, or any other useful specification

Value

A 'data.table' containing the original data, plus one new timeStamp, and optionally computed time differences :

• 'timeStamp': The current timeStamp ('POSIXct').

• 'timeStamp_num': timeStamp converted to numeric, useful for intermediary calculations.

• 'dt_num': The time difference in seconds between consecutive rows as a numeric value.

• 'dt_text': The formatted time difference in seconds with milliseconds as a character string.

• Additional columns for any information provided by the user via '...'. It allows documentation about the current step running, substeps, which version is being tested, ...

Examples

# compare code speed between using a loop, or the mean() function
library(data.table)
library(dplyr)
tmr <- data.table()  # Initialize timer
vec <- rnorm(1e6)    # Example vector

tmr <- timer(tmr, method = "loop")   # timeStamp : 1st step =================
total <- 0
for (i in seq_along(vec)) total <- total + vec[i]
mean_loop <- total / length(vec)

tmr <- timer(tmr, method = "mean()") # timeStamp : 1st step =================
mean_func <- mean(vec)

tmr <- timer(tmr, end = TRUE)        # timeStamp : close timer ==============

t_step1 <- tmr[method == "loop"]$dt_num
t_step2 <- tmr[method == "mean()"]$dt_num
diff_pc <- (t_step2/t_step1 - 1) * 100
diff_txt <- format(diff_pc, nsmall = 0, digits = 1)

# view speed difference
print(tmr %>% select(-matches("_num$")))
paste0("speed difference : ", diff_txt, "%")

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