fun.mApply {GLDEX}

Applying functions based on an index for a matrix.

Description

This is a generic function that can be used to find mean, variance, sum or other operations according to some index imposed on the matrix or vector.

Usage

fun.mApply(X, INDEX, FUN = NULL, ..., simplify = TRUE)

Arguments

X

Matrix with n rows.

INDEX

Vector or list of vectors of length n.

FUN

Function to operate on submatrices of X by INDEX

...

Arguments to function.

simplify

Set as TRUE by default, see sapply fo details.

Value

If FUN returns more than one number, fun.mApply returns a matrix with rows corresponding to unique values of INDEX.

Author(s)

Tony Plate

Examples

 
# Finding the row medians of a matrix (matrix(1:20,nrow=5))
fun.mApply(matrix(1:20,nrow=5),list(1:5),median)