format.hms() accepting argument format

[retodomax]

There seems to be a format() S3 method for class 'hms'. However, it just returns the input as character. I would have expected that it takes the argument format and formats the output like an object of class POSIXct

library(hms)
t <- Sys.time()
format(t, "%H")
#> [1] "17"

t2 <- as_hms(t)
format(t2, "%H")
#> [1] "17:12:38.169816"

^{Created on 2024-11-05 with reprex v2.1.1}

[krlmlr]

Thanks. The hms type inherits from difftime, that type doesn't seem to support the format() syntax you're suggesting either:

d <- Sys.time() - Sys.time()
d
#> Time difference of -9.536743e-07 secs
format(d, "%H")
#> Error in prettyNum(.Internal(format(x, trim, digits, nsmall, width, 3L, : invalid 'trim' argument

^{Created on 2024-11-10 with reprex v2.1.1}

Here's what I think happens: format() is forwarded to format.default(), and the "%H" is matched to the trim argument.

format.difftime
#> function (x, ...) 
#> {
#>     if (length(x)) 
#>         paste(format(unclass(x), ...), units(x))
#>     else character()
#> }
#> <bytecode: 0x10527d070>
#> <environment: namespace:base>
formals(format.default)
#> $x
#> 
#> 
#> $trim
#> [1] FALSE
#> 
#> $digits
#> NULL
#> 
#> $nsmall
#> [1] 0
#> 
#> $justify
#> c("left", "right", "centre", "none")
#> 
#> $width
#> NULL
#> 
#> $na.encode
#> [1] TRUE
#> 
#> $scientific
#> [1] NA
#> 
#> $big.mark
#> [1] ""
#> 
#> $big.interval
#> [1] 3
#> 
#> $small.mark
#> [1] ""
#> 
#> $small.interval
#> [1] 5
#> 
#> $decimal.mark
#> getOption("OutDec")
#> 
#> $zero.print
#> NULL
#> 
#> $drop0trailing
#> [1] FALSE
#> 
#> $...

^{Created on 2024-11-10 with reprex v2.1.1}

[retodomax]

Thanks for the reply!
I guess, ideal would be, if this feature would be implemented in base R but hard to say if they want it there...
If you're interested, I could try to write a method implementing the feature for package hms where in my opinion it would make sense to be able to extract/format specific time components (hours, minutes, ...) as string.