[R] Summary of data.frame according to colnames and grouping factor

2009-03-08 Thread soeren . vogel
A dataframe holds 3 vars, each checked true or false (1, 0). Another var holds the grouping, r and s: ### start:example set.seed(20) d - data.frame(sample(c(0, 1), 20, replace=T), sample(c(0, 1), 20, replace=T), sample(c(0, 1), 20, replace=T)) names(d) - c(A, B, C) e - rep(c(r, s), 10) ###

Re: [R] Summary of data.frame according to colnames and grouping factor

2009-03-08 Thread baptiste auguie
Hi, You could use the reshape package: d$e - e recast(d, variable~e, fun=sum) The doBy package is another option. baptiste On 8 Mar 2009, at 17:14, soeren.vo...@eawag.ch wrote: A dataframe holds 3 vars, each checked true or false (1, 0). Another var holds the grouping, r and s: ###

Re: [R] Summary of data.frame according to colnames and grouping factor

2009-03-08 Thread David Winsemius
If you prefer to do it with base functions, you could start by thinking about one column at a time, for which the tapply function is a logical choice: tapply(d[,A], e, sum) r s 3 6 Then wrap that in an apply call that handles each column sequentially: apply(d, 2, function (x) tapply(x, e,