[R] how to sum multiple data entries for the same sampling event?

[R. Michael Weylandt]

Perhaps something like

# Untested
library(plyr)
ddply(DATA, "Date", function(d) sum(d$lmb.cpue))

For example, on some fake data

DATA <- data.frame(class = rep(letters[1:5], each = 2), type =
rep(c("good", "bad"), 5), value = rnorm(10))
ddply(DATA, "class", function(d) sum(d$value))

If you want to send example data, it's best to send it with the
plaintext output of dput().

Michael

On Mon, Jan 30, 2012 at 12:16 PM, karengrace84 <kgfisher at alumni.unc.edu> wrote:
> I'm having trouble with some catch per unit effort data (CPUE, fisheries
> data). Some of the samples were "retained" and some "unretained," and they
> are entered as 2 separate entries for the same sampling event (Date and
> time). I want to calculate the total CPUE (so sum the "retained" and
> "unretained" number for each sampling event) and am having troubld doing so.
> Here's a sample of what my data.frame looks like now:
>
> Date                               lmb.cpue
> Disposition.of.Catch
> 1999-07-10 12:10:00   0.66666667           Unretained
> 1999-07-10 12:10:00   0.16666667             Retained
> 1999-07-14 11:22:00   0.83333333           Unretained
> 1999-07-14 11:22:00   0.55555556             Retained
> 1999-07-14 11:48:00   0.16666667           Unretained
> 1999-07-14 11:48:00   0.58333333             Retained
> 1999-07-14 13:56:00   0.57142857             Retained
> 1999-07-15 10:23:00   0.11111111             Retained
> 1999-07-22 12:03:00   0.33333333             Retained
> 1999-07-25 11:26:00   0.40000000           Unretained
> 1999-07-25 11:26:00   1.00000000             Retained
>
>
> And I would like to end up with:
>
> Date                               lmb.cpue
> 1999-07-10 12:10:00   0.83333333
> 1999-07-14 11:22:00   1.38888889
> 1999-07-14 11:48:00   0.75000000
> 1999-07-14 13:56:00   0.57142857
> 1999-07-15 10:23:00   0.11111111
> 1999-07-22 12:03:00   0.33333333
> 1999-07-25 11:26:00   1.40000000
>
> Thanks for any help you have to offer!
>
> --
> View this message in context: http://r.789695.n4.nabble.com/how-to-sum-multiple-data-entries-for-the-same-sampling-event-tp4341670p4341670.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.