Skip to contents

Column-wise tied ranks of a matrix

rank_matrix.Rd

Ranks the entries of each column independently using the average rank for ties, and returns the per-column tie group sizes needed for the Wilcoxon variance correction. Used internally by wilcoxauc() (on a transposed input, so that rows become observations) but exposed as a fast standalone ranking primitive for sparse and dense numeric matrices.

Usage

rank_matrix(X)

# S3 method for class 'dgCMatrix'
rank_matrix(X)

# S3 method for class 'matrix'
rank_matrix(X)

Arguments

X

Numeric matrix or dgCMatrix.

Value

List with two elements:

  • X_ranked - matrix with the same shape as X containing per-column tied ranks.

  • ties - list of integer vectors, one per column, giving the sizes of all tie groups encountered in that column. Used by the Wilcoxon statistic to correct for ties.

See also

wilcoxauc()

Examples

set.seed(42)
exprs <- matrix(rpois(25 * 150, lambda = 2), nrow = 25,
                dimnames = list(paste0("G", 1:25), NULL))
rank_res <- rank_matrix(exprs)