[R] A problem with string handling to make a time duration
john.laing at gmail.com
Mon May 4 23:14:02 CEST 2015
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.
On Mon, May 4, 2015 at 3:59 PM, gavinr <g.rudge at 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" ))
> #ideally should look like:
> 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
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