Get matrix from a Daf object — get_matrix • dafJuliaWrapper

Retrieves a matrix property with the specified name for the given axes from the Daf data set.

Usage

get_matrix(daf, rows_axis, columns_axis, name, default = NULL, relayout = TRUE)

Arguments

daf: A Daf object
rows_axis: Name of rows axis
columns_axis: Name of columns axis
name: Name of the matrix property
default: Default value if matrix doesn't exist (NULL by default)
relayout: Whether to allow retrieving matrix with flipped axes (TRUE by default)

Value

A matrix with row and column names set to the axis entry names, or the default value if the property doesn't exist

Details

Matrix properties store two-dimensional data along two axes. If the matrix doesn't exist and default is NA, a matrix of NAs with appropriate dimensions is returned. If relayout is TRUE and the matrix exists with flipped axes, it will be transposed automatically.

For zero-copy-eligible element types, the returned matrix is a live view over Julia-side memory; sparse CSC matrices are also zero-copy via jlview::jlview_sparse. Mutating the Daf through set_matrix() or file-mapped writes may alter the contents of a previously returned matrix. Copy explicitly if stability across modifications is required. See the Julia documentation for details.

Examples

if (FALSE) { # \dontrun{
setup_daf()
daf <- memory_daf("example")
add_axis(daf, "cell", c("A", "B"))
add_axis(daf, "gene", c("X", "Y", "Z"))
mat <- matrix(1:6, nrow = 2, ncol = 3)
set_matrix(daf, "cell", "gene", "UMIs", mat)
get_matrix(daf, "cell", "gene", "UMIs")
} # }