applyByCategory: Apply a function to a vector of statistics, by category
In Category: Category Analysis

Description Usage Arguments Details Value Author(s) See Also Examples

For each category, apply the function FUN to the set of values of stats belonging to that category.

1	applyByCategory(stats, Amat, FUN = mean, ...)

`stats`	Numeric vector with test statistics of interest.
`Amat`	A logical or numeric matrix: the adjacency matrix of the bipartite genes - category graph. Its rows correspond to the categories, columns to the genes, and `TRUE` or a numeric value different from `0` indicates membership. The columns are assumed to be aligned with the elements of `stats`.
`FUN`	A function to apply to the subsets `stats` by categories.
`...`	Extra parameters passed to `FUN`.

For GO categories, the function cateGOry might be useful for the construction of Amat.

The return value is a list or vector of length equal to the number of categories. Each element corresponds to the values obtained by applying FUN to the subset of values in stats according to the category defined for that row.

R. Gentleman, contributions from W. Huber

apply

 set.seed(0xabcd)
 st = rnorm(20)
 names(st) = paste("gene", 1:20)

 a = matrix(sample(c(FALSE, TRUE), 60, replace=TRUE), nrow=3,
        dimnames = list(paste("category", LETTERS[1:3]), names(st)))

 applyByCategory(st, a, median)