>>>>> Reuver, B de \(epi\) via R-help
>>>>> on Wed, 23 Oct 2024 08:11:50 +0000 writes:
> Hello,
> I was working on an R script using the datediff object, to log certain
durations in the data processing.
> I ran in to the issue that outputing a datediff object using PASTE will
leave out the time unit by default.
> When you paste() or as.character() a datediff object it only outputs the
numeric value, for example "1.23", so without the time unit secs, minutes,
hours etc. This is arguably is not very useful, because 1.23 seconds is very
different from 1.23 hours.
> ```
> start_time <- Sys.time()
> result <- sum(1:10000)
> dur_time <- Sys.time() - start_time
Note that print( ... ) below is unneeded:
in R's toplevel, "auto" print() is (almost) always called
> print(paste(Sys.time(), "the process duration:", dur_time)) # "2024-10-23
09:57:10.69578 the process duration: 0.00280904769897461"
> print(dur_time) # "Time difference of 0.002809048 secs"
> print(paste(dur_time)) # "0.00280904769897461"
> print(as.character(dur_time)) # "0.00280904769897461"
> print(format(dur_time)) # "0.002809048 secs"
i.e., the format() method is doing the right thing, as it should.
The as.character() method shouldn't (and will not) be changed here.
> print(paste(dur_time, attr(dur_time, "units"))) # "0.00280904769897461
secs"
> ```
> So my questions are:
> 1) is it possible to have the default output for as.character for the
datediff object also include the time unit? That way, it automatically outputs
for example "1.23 seconds" when used in combination with paste().
No, see above. You should use format() in such situations, not
just for "difftime" objects.
> If someone really need just the numeric value without the unit, you can
already use as.numeric(dur_time).
indeed.
But as as.character() is defined (typically / in base R) to get rid of
attributes.
> 2) Is it possible to expand the format() options for the datediff object,
so that it also accepts a strptime-like string, so like %H:%M:%S ? That way you
have more output options without having to rely on third-party libraries
That would be possible, but I'm not at all sure that it's
desirable / necessary .. (but opinions may differ, I may change
mine after some good discussion...).
Did you look at the ?difftime help page and its 'Examples' ?
I think everything you need is almost available.
The formatting in %H:%M .. etc is not directly possible,
and I think for good reasons:
Somewhat experienced R users can currently quickly see the
difference between Date, Date-Times, and "difftime" objects
from their print output, and I think that is desirable.
start_time <- structure(1729777, class = c("POSIXct", "POSIXt"))
result <- sum(1:10000)
nowTime <- structure(1729888.123123123, class = c("POSIXct", "POSIXt"))
## ^^^^^^^^^^ to see precision (not soo accurate with
POSIXct!)
(dur_time <- nowTime - start_time) # -> print
## Time difference of 1.852052 mins
format(dur_time) # --> "1.852052 mins" -- MM: isn't that good!
format(dur_time, digits=12) # --> "1.85205205205 mins"
## You can switch from minutes to seconds :
dtime <- dur_time; units(dtime) <- "secs"
dtime ## Time difference of 111.1231 secs
format(dtime, digits = 10)
## [1] "111.1231231 secs"
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