Regular expressions are the tool for this problem. This pattern
matches your input data:
t <- c("10H20M33S", "1H1M", "1M", "21M9S", "2H55S")
patt <- "^(([0-9]+)H)?(([0-9]+)M)?(([0-9]+)S)?$"
all(grepl(patt, t)) # TRUE
We can use the pattern to extract hour/minute/second components
hms <- lapply(c(h="\\2", m="\\4", s="\\6"), function(r) sub(patt, r, t))
And then just plug those components back into the desired format
formatted <- gsub(" ", "0", sprintf("%2s:%2s:%2s", hms$h, hms$m, hms$s))
In the last line we need the gsub because zero-padding with %02s seems
to be platform-dependent.
JL
On Mon, May 4, 2015 at 3:59 PM, gavinr <g.ru...@bham.ac.uk> wrote:
> I have a character string that represents a time duration. It has an hours
> minutes seconds structure(ish) but with letters denoting units (H,M or S) no
> leading zeros and no placeholder at all where one or other of the units are
> not required.
>
> It looks like this:
>
> t<-c("10H20M33S","1H1M","1M","21M9S","2H55S" ))
> df<-data.frame(t)
> df
>
> #ideally should look like:
> t2<-c("10:20:33","01:00:01","00:01:00","00:21:09","02:00:55")
> df2<-data.frame(t2)
> df2
>
> I need to get it into hours minutes and seconds either in time format or as
> a string with leading zeros and all three time units represented in each
> one, as in df2. The data, part of a very large dataset, are for onward use
> and processing in a GIS application. I’ve messed about with string handling
> statements in SQL to no avail, but wondered if R would be a better bet?
> I’ve had a look at some of the commands in stringr, but am unsure how to
> operationalise a solution using this package. Any advice is welcome.
>
>
>
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/A-problem-with-string-handling-to-make-a-time-duration-tp4706795.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
