Time data

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It depends on how you want to work with the data.  Here is an example
of converting both to POSIXct and a numeric value:
x <- c('1:24', '13:46')
# convert to POSIXct
x.POSIXct <- as.POSIXct(x, format = '%H:%M')
x.POSIXct
[1] "2011-04-14 01:24:00 EDT" "2011-04-14 13:46:00 EDT"
# to get a numeric value representing the hour
x.hour <- do.call(rbind, strsplit(x, ":"))  # create matrix
# convert to numeric
mode(x.hour) <- 'numeric'
# convert to hour
x.hour %*% c(1, 1/60)
[,1]
[1,]  1.40000
[2,] 13.76667

On Wed, Apr 13, 2011 at 5:29 PM, Gregory Pierce
Hello fellow R-users,

I have a data set that includes times in the hh:mm format. I am uncertain
how to tell R that it is time data. Currently when I try to calculate a mean
with this time subset, I get an error message:

mean(mar2011stats$TT)
[1] NA
Warning message:
In mean.default(mar2011stats$TT) :
?argument is not numeric or logical: returning NA

TT is the column label under which I have stored my time data: (for example,
1:24 to represent one hour and twenty four minutes).

Do I have to convert everything to minutes so that R can deal with it as it
would other numerical values?

Thanks,
Greg

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