Aliases: sparseby
### ** Examples x <- data.frame(index=c(rep(1,4),rep(2,3)),value=c(1:7)) x
index value 1 1 1 2 1 2 3 1 3 4 1 4 5 2 5 6 2 6 7 2 7
sparseby(x,x$index,nrow)
Warning in all(lapply(result, function(x) length(dim(x)) == 2)): coercing argument of type 'list' to logical
Warning in all(lapply(list(...), is.numeric)): coercing argument of type 'list' to logical
x$index 1 1 4 2 2 3
# The version below works entirely in matrices x <- as.matrix(x) sparseby(x,list(group = x[,"index"]), function(subset) c(mean=mean(subset[,2])))
Warning in all(lapply(list(...), is.numeric)): coercing argument of type 'list' to logical
Warning in all(lapply(result, function(x) length(dim(x)) == 2)): coercing argument of type 'list' to logical
Warning in all(lapply(list(...), is.numeric)): coercing argument of type 'list' to logical
group mean 1 1 2.5 2 2 6.0