Thank you for the suggestion. Tried it as :
MeansByDoseDayTime <- aggregate(as.double(PK04Sub$Concentration.ng.mL.), by =
list(PK04Sub$Dose.Level, PK04Sub$Day, PK04Sub$HourNominal), FUN =
function(x) c( mean(x, trim = 0, na.rm = T, weights=NULL),
sd(x, na.rm=TRUE),
median(x, na.rm=TRUE),
min(x, na.rm=TRUE),
max(x, na.rm=TRUE)
)
)
and got the following error message.
Problem in FUN(...X.sub.i...., all.indices = c(1, 2..: FUN did not always
return a scalar
Suggestions?
Regards,
Michael
-----Original Message-----
From: David Winsemius [mailto:dwinsem...@comcast.net]
Sent: Thursday, February 23, 2012 1:55 PM
To: Michael Karol
Cc: r-help@r-project.org
Subject: Re: [R] Aggregate with Function List ?
On Feb 23, 2012, at 1:41 PM, Michael Karol wrote:
> R Experts
>
>
>
> I wish to tabulate into one data frame statistics summarizing
> concentration data. The summary is to include mean, standard
> deviation, median, min and max. I wish to have summaries by Dose, Day
> and Time. I can do this by calling aggregate once for each of the
> statistics (mean, standard deviation, median, min and max) and then
> execute 4 merges to merging the 5 data frames into one. (Example
> aggregate code for mean only is shown below.)
>
> Can someone show me the coding to do this as one command, rather than
> 5 calls to aggregate and 4 merges. In other words, in essence, I'd
> like to present to "FUN =" a list of functions, so all the summary
> stats come back in one data frame. Your assistance is appreciated.
> Thank you.
>
Perhaps something like this?
MeansByDoseDayTime <- aggregate(as.double(DF$Concentration), by = list(DF$Dose,
DF$Day, DF$Time), FUN =
function(x) c( mean(x, trim = 0, na.rm = T, weights=NULL),
sd(x, na.rm=TRUE),
median(x, na.rm=TRUE),
min(na.rm=TRUE),
max(x, na.rm=TRUE)
)
)
>
>
>
David Winsemius, MD
West Hartford, CT
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