On Aug 8, 2011, at 7:51 PM, Jeffrey Joh wrote:


Here is a sample of what I'm trying to do:

structure(list(C_lo = c(0.00392581816943354, 0.00901222644518829,
0.00484396253385175, 0.00822377400482716, 0.00780070460187192,
0.00952688235337435), C_hi = c(0.00697755827622381, 0.0123301031600017, 0.0113207627868435, 0.0112887993422598, 0.018567245397701, 0.0195253894885054
),  house = c(1, 1, 1, 1, 1, 1), date = c(719, 1027, 1027,
1027, 1030, 1030), hour = c(18, 8, 8, 8, 11, 11), .Names = c("1000", "10000",
   "10001", "10002", "10003", "10004"),  press = structure(c(1L,
   1L, 1L, 1L, 1L, 1L), .Names = c("1000", "10000",
   "10001", "10002", "10003", "10004"), .Label = c("DEPR",
   "PRESS"), class = "factor")), .Names = c("C_lo", "C_hi",
"house", "date", "hour", "number", "press"
), class = "data.frame", row.names = c("1000", "10000",
"10001", "10002", "10003", "10004"))



I'd like to aggregate the data by the date. I'd like to have a table with the median C_lo and C_hi values grouped by date. I'd also like to plot these points with date on the x-axis, C on y- axis, and lines going through these medians.


> aggregate(results[, c("C_lo", "C_hi")], results["date"], median)
  date        C_lo        C_hi
1  719 0.003925818 0.006977558
2 1027 0.008223774 0.011320763
3 1030 0.008663793 0.019046317

dat <-.Last.value
matplot(dat[1], dat[-1], type="b", ylim=with(results, range(c(C_lo, C_hi)) ) )
 with(results, points(date, C_lo))
 with(results, points(date, C_hi))

--
David.



For plyr, would it be something like: ddply(results, .(date),median, na.rm=T)



I tried making a for loop to get the medians, but that doesn't work either.
splitresults = split (results, results$date, drop=T)
mediann <- matrix (,seq_along(splitresults),2)
for (i in seq_along(splitresults)) {
piece <- splitresults[[i]]
mediann [i,1] <- unique(piece$date)
mediann [i,2] <- median (piece$n, na.rm=T)
}



Jeff



----------------------------------------
Date: Fri, 5 Aug 2011 11:59:37 -0700
Subject: Re: [R] Aggregating data
From: djmu...@gmail.com
To: johjeff...@hotmail.com
CC: r-help@r-project.org

Hi:

This is the type of problem at which the plyr package excels. Write a
utility function that produces the plot you want using a data frame as
its input argument, and then do something like

library('plyr')
d_ply(results, .(a, b, c), plotfun)

where plotfun is a placeholder for the name of the name of your plot
function. The d in d_ply means to take a data frame as input and _
means return nothing. This is used in particular when a side effect,
such as a plot, is the desired 'output'. See
http://www.jstatsoft.org/v40/i01, which contains an example (baseball)
where groupwise plots are produced. (Don't actually run the example
unless you're willing to wait for 1100+ ggplots to be rendered :)

If memory serves, you should also be able to produce graphics for each
data subset using the data.table package as well.

If you want a more concrete solution, provide a more concrete example.

HTH,
Dennis

On Fri, Aug 5, 2011 at 9:55 AM, Jeffrey Joh <johjeff...@hotmail.com> wrote:


I aggregated my data: aggresults <-aggregate(results, by=list(results$a, results$b, results$c), FUN=mean, na.rm=TRUE)



results has about 8000 lines of data, and aggresults has about 80 lines. I would like to create a separate variable for each of the 80 aggregates, each containing the 100 lines that were aggregated. I would also like to create plots for each of those 80 datasets.



Is there a way of automating this, so that I don't have to do each of the 80 aggregates individually?



Jeff
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David Winsemius, MD
West Hartford, CT

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