BigDataStatMeth (version 2.0.3)

crossprod: Cross product of HDF5Matrix objects

Description

S3 generic for crossprod(). Dispatches to crossprod.HDF5Matrix for HDF5Matrix objects, and to base::crossprod() for all others.

Usage

crossprod(x, y = NULL, ...)
# S3 method for HDF5Matrix
crossprod(x, y = NULL, outgroup = NULL, outdataset = NULL, ...)

Value

Result of the cross product.

A new HDF5Matrix pointing to the result dataset.

Arguments

x

An HDF5Matrix object.

y

An HDF5Matrix object, or NULL (default) to compute t(x) %*% x.

...

Ignored.

outgroup

Character or NULL. HDF5 group where the result is stored. Default "OUTPUT".

outdataset

Character or NULL. Dataset name for the result. Default "CrossProd_x" (single matrix) or "CrossProd_x_x_y" (two matrices).

Details

Computes \(t(x) \times y\) (or \(t(x) \times x\) when y = NULL). Uses the dedicated BigDataStatMeth block-wise cross-product algorithm, which is more efficient than explicitly computing t(x) %*% y.

Performance settings:

This method uses global options set via hdf5matrix_options.

Symmetric optimization:

When y = NULL or y refers to the same dataset as x, the symmetric optimisation (bisSymetric = TRUE) is applied automatically, providing significant speedup.

See Also

hdf5matrix_options for global performance settings

Examples

# \donttest{
fn <- tempfile(fileext = ".h5")
X <- hdf5_create_matrix(fn, "INPUT/X", data = matrix(rnorm(60), 6, 10))
Y <- hdf5_create_matrix(fn, "INPUT/Y", data = matrix(rnorm(60), 6, 10))

# t(X) %*% X  → stored in OUTPUT/CrossProd_X
C1 <- crossprod(X)
dim(C1)

# t(X) %*% Y  → stored in OUTPUT/CrossProd_X_x_Y
C2 <- crossprod(X, Y)

# Custom output location
C3 <- crossprod(X, outgroup = "RESULTS", outdataset = "my_crossprod")

hdf5_close_all()
unlink(fn)
# }