rowMeansx: Some Further Row and Column Functions

In RandomFieldsUtils: Utilities for the Simulation and Analysis of Random Fields and Genetic Data

Some Further Row and Column Functions

Description

The function rowMeansx returns weighted row means;
the function colMax returns column maxima;
the function rowProd returns the product of each row;
the function quadratic calculates a quadratic form
the function SelfDivByRow devides each column by a scalar;
the function dotXV calculates columnwise the dot product;
the function crossprodx calculates the cross product (using AVX);
the function scalarx calculates the scalar product (using AVX);

Usage

rowMeansx(x, weight=NULL)
colMax(x)
rowProd(x)
SelfDivByRow(x, v)
quadratic(x, v)
dotXV(x, w)
crossprodx(x,y,mode=-1)
scalarx(x, y, mode=0) 

Arguments

x	numerical (or logical) matrix
v	vector whose length equals the number of columns of x
w	vector whose length equals the number of rows of x
weight	numerical or logical vector of length nrow(x)
y	numerical matrix
mode	integer between 0 and 8 or negative, indicating that the default value should be used. Determine the algorithm how the scalar product is calculated. These values are experimental and may change their meaning.

Details

quadratic(x, v) calculates the quadratic form v^\top x v; The matrix x must be squared.

Value

rowMeansx returns a vector of lengthnrow(x).

colMax returns a vector of length ncol(x).

rowProd returns a vector of length nrow(x).

quadratic returns a scalar.

SelfDivByRow returns a matrix of same size as x.

dotXV returns a matrix of same size as x.

Examples

c <- if (interactive()) 10000 else 10
r <- if (interactive()) 20000 else 20
M <- matrix(nr=r, 1:(c * r))

## unweighted means, compare to rowMeans
print(system.time(m1 <- rowMeans(M)))
print(system.time(m2 <- rowMeansx(M)))
stopifnot(all.equal(m1, m2))

## weighted row means, compare to rowMeans
W <- 1 / (ncol(M) : 1)
print(system.time({M0 <- t(W * t(M)); m1 <- rowMeans(M0)}))
print(system.time(m2 <- rowMeansx(M, W)))
stopifnot(all.equal(m1, m2))

print(system.time(m1 <- apply(M, 2, max)))
print(system.time(m2 <- colMax(M)))
stopifnot(m1 == m2)

RandomFieldsUtils documentation built on April 19, 2022, 5:09 p.m.