rowMeansx | R Documentation |
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);
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)
x |
numerical (or logical) matrix |
v |
vector whose length equals the number of columns of |
w |
vector whose length equals the number of rows of |
weight |
numerical or logical vector of length |
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. |
quadratic(x, v)
calculates the quadratic form v^\top x v;
The matrix x
must be squared.
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
.
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)
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.