reduced.dim.matrix {SingleCellExperiment} | R Documentation

## The reduced.dim.matrix class

### Description

A matrix class that retains its attributes upon being subsetted or combined. This is useful for storing metadata about a dimensionality reduction result alongside the matrix, and for ensuring that the metadata persists when the matrix is stored inside `reducedDims`.

### Constructor

`reduced.dim.matrix(x, ...)` will return a reduced.dim.matrix object, given a matrix input `x`. Arguments in `...` should be named and are stored as custom attributes in the output. Any arguments named `dim` or `dimnames` are ignored.

### Subsetting

`x[i, j, ..., drop=FALSE]` will subset a reduced.dim.matrix `x` in the same manner as a base matrix. The only difference is that a reduced.dim.matrix will be returned, retaining any custom attributes in `x`. Note that no custom attributes are retained if the return value is a vector with `drop=TRUE`.

### Combining

`rbind(...)` will combine multiple reduced.dim.matrix inputs in `...` by row, while `cbind(...)` will combine those inputs by column.

If the custom attributes are the same across all objects `...`, a reduced.dim.matrix is returned containing all combined rows/columns as well as the custom attributes.

If the custom attributes are different, a warning is issued. A matrix is returned containing all combined rows/columns; no custom attributes are retained.

### Author(s)

Aaron Lun

### See Also

`reducedDims`, to store these objects in a SingleCellExperiment.

### Examples

    # Typical PC result, with metadata stored in the attributes:
    pc <- matrix(runif(500), ncol=5)
    attr(pc, "sdev") <- 1:100
    attr(pc, "rotation") <- matrix(rnorm(20), ncol=5)

    # Disappears upon subsetting and combining!
    attributes(pc[1:10,])
    attributes(rbind(pc, pc))

    # Transformed into a reduced.dim.matrix:
    rd.pc <- reduced.dim.matrix(pc)

    attributes(rd.pc[1:10,])
    attributes(rbind(rd.pc, rd.pc))

[Package SingleCellExperiment version 1.14.1 Index]