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.

 

MeansByDoseDayTime <- aggregate(as.double(DF$Concentration), by =
list(DF$Dose, DF$Day, DF$Time), FUN = mean, trim = 0, na.rm = T,
weights=NULL)

 

 

Regards, 

Michael


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