How to get the time elapsed between two points?

I've tried to use Sys.time to get the time elapsed between two points. However, it doesn't output in a way I like.

This is how it looks now:

a <- Sys.time
...running stuff between these two points...
b <- Sys.time
c <- b - a
c
Time difference of 1.00558 hours

I only want the number and the units. I know that to get just the number I can do:

c[[1]]

However, sometimes the result of c can give me seconds or minutes. I only want instances wherein I have the number and when the units are in hours. Does anyone know of a way such that I would get something like the following, using Sys.time() (or any alternative):

if (units == "hours")
{
  if (number => 1)
  {
      #do something
  }
}

---

Using difftime of base R allows you to obtain the time difference in different units. Rest is formatting.

a = Sys.time()
Sys.sleep(5)    #do something
b = Sys.time()    
paste0(round(as.numeric(difftime(time1 = b, time2 = a, units = "secs")), 3), " Seconds")
#[1] "5.091 Seconds"

---

You can evaluate everything as an argument to the system.time function. It will give you the elapsed time in seconds.

paste0(system.time( rnorm(1000000, 0, 1) )[3] / 3600, " hours")
# "2.58333333334172e-05 hours"

Alternatively, you can use Frank's suggestion in the comments. difftime(b, a, units = "hours") which is probably the dominant solution in most cases

---

Maybe you can try the ´tictoc´ package. As described in the documentation you can do the following:

tic()

#Do something

toc(log = TRUE, quiet = TRUE)

#Put the result in a log
log.txt <- tic.log(format = TRUE)

#Extract only the value
res <- gsub( " sec elapsed", "", unlist(log.txt))

#Clear the log
tic.clearlog()

That way, res gives you only the value and is in seconds, so it is pretty simple to have hours then. Moreover, if you don't clear the log you can put successions of tic() and toc() and put everything in your log.txt , and then gsub( " sec elapsed", "", unlist(log.txt)) will give you a vector of strings with the value in seconds for each iteration which can be pretty useful

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