I have not used POSIX classes previously and now have a need to use them. I
have sports data with times of some athletes after different events. I need to
perform some simple analyses using the times. I think I've figured out how to
do this. I just want to confirm with others who have more experience that this
is indeed the correct approach. If not, please suggest a more appropriate way.
Suppose I have times for two athletes after event 1.
> times <- c('14:15', '16:45')
Now, I use strptime() as follows
> x <- strptime(times, "%M:%S")
> x
[1] "2010-04-02 00:14:15" "2010-04-02 00:16:45"
> class(x)
[1] "POSIXt" "POSIXlt"
Now, I want the average time across all athletes as well as the min and max, so
I do:
> mean(x); min(x); max(x)
[1] "2010-04-02 00:15:30 EDT"
[1] "2010-04-02 00:14:15 EDT"
[1] "2010-04-02 00:16:45 EDT"
Now, I want to rank order the athletes:
> rank(x)
Error in if (xi == xj) 0L else if (xi > xj) 1L else -1L :
missing value where TRUE/FALSE needed
But, I can rank order the following.
> rank(times)
[1] 1 2
I don't need the date in the object x, but I can't figure out how to remove it.
Nonetheless, it doesn't seem to affect anything.
> x
[1] "2010-04-02 00:14:15" "2010-04-02 00:16:45"
Is this the right approach for using time variables and performing some
computations on them? Or, is there another approach I should look at.
Thanks,
Harold
> sessionInfo()
R version 2.10.0 (2009-10-26)
i386-pc-mingw32
locale:
[1] LC_COLLATE=English_United States.1252 LC_CTYPE=English_United States.1252
[3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C
[5] LC_TIME=English_United States.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] lme4_0.999375-32 Matrix_0.999375-31 lattice_0.17-26
loaded via a namespace (and not attached):
[1] grid_2.10.0 tools_2.10.0
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