Re: [R] using tapply with multiple variables

2011-05-01 Thread Dennis Murphy
Hi: If you have R 2.11.x or later, one can use the formula version of aggregate(): aggregate(Correct ~ Subject + Group, data = ALLDATA, FUN = function(x) sum(x == 'C')) A variety of contributed packages (plyr, data.table, doBy, sqldf and remix, among others) have similar capabilities. If you

Re: [R] using tapply with multiple variables

2011-05-01 Thread Andrew Robinson
This is a nice demonstration of the formula interface to aggregate. A less elegant alternative is to pass lists as arguments. with(dd, aggregate(Correct, by = list(Subject = Subject, Group = Group), FUN = function(x) sum(x == 'C')))

[R] using tapply with multiple variables

2011-04-30 Thread Kevin Burnham
HI All, I have a long data file generated from a minimal pair test that I gave to learners of Arabic before and after a phonetic training regime. For each of thirty some subjects there are 800 rows of data, from each of 400 items at pre and posttest. For each item the subject got correct, there

Re: [R] using tapply with multiple variables

2011-04-30 Thread jim holtman
Since you did provide a description of your data (e.g., at least 'str(ALLDATA)') so that we know its structure, I will take a guess: tapply(ALLDATA$Correct, list(ALLDATA$Subject, ALLDATA$Time), function(x)sum(x==C)) On Sat, Apr 30, 2011 at 3:28 PM, Kevin Burnham kburn...@gmail.com wrote: HI

Re: [R] using tapply with multiple variables

2011-04-30 Thread Jim Lemon
On 05/01/2011 05:28 AM, Kevin Burnham wrote: HI All, I have a long data file generated from a minimal pair test that I gave to learners of Arabic before and after a phonetic training regime. For each of thirty some subjects there are 800 rows of data, from each of 400 items at pre and