expandAsMatrix {edgeR} | R Documentation

## expandAsMatrix

### Description

Expand scalar or vector to a matrix.

### Usage

    expandAsMatrix(x, dim=NULL, byrow=TRUE)

### Arguments

`x` | scalar, vector, matrix or CompressedMatrix.
`dim` | integer vector of length 2 specifying the required dimensions of the output matrix.
`byrow` | logical scalar specifying if matrix should be filled by columns or rows for a vector `x`.

### Details

This function expands a scalar, row/column vector or CompressedMatrix to be a matrix of dimensions `dim`. It is used internally in edgeR to convert offsets, weights and other values to a matrix for consistent handling. If `dim` is `NULL`, the function is equivalent to calling `as.matrix(x)`.

If `x` is a vector, its length must match one of the output dimensions. The matrix will then be filled by repeating the matrix across the matching dimension. For example, if `length(x)==dim[1]`, the matrix will be filled such that each row contains `x`. If both dimensions match, filling is determined by `byrow`, with filling by rows as the default.

If `x` CompressedMatrix object, the size of any non-repeated dimensions must be consistent with corresponding output dimension. The `byrow` argument will be ignored as the repeat specifications will dictate how expansion should be performed. See `?CompressedMatrix` for more details.

### Value

Numeric matrix of dimension `dim`.

### Author(s)

Gordon Smyth

### Examples

    expandAsMatrix(1:3,c(4,3))
    expandAsMatrix(1:4,c(4,3))

[Package edgeR version 3.24.3 Index]