Transpose the storage order for a matrix

## Usage

```
transpose_storage_order(
matrix,
outdir = tempfile("transpose"),
tmpdir = tempdir(),
load_bytes = 4194304L,
sort_bytes = 1073741824L
)
```

## Arguments

- matrix
Input matrix

- outdir
Directory to store the output

- tmpdir
Temporary directory to use for intermediate storage

- load_bytes
The minimum contiguous load size during the merge sort passes

- sort_bytes
The amount of memory to allocate for re-sorting chunks of entries

## Value

MatrixDir object with a copy of the input matrix, but the storage order flipped

## Details

This re-sorts the entries of a matrix to change the storage order
from row-major to col-major. For large matrices, this can be slow – around 2
minutes to transpose a 500k cell RNA-seq matrix The default load_bytes (4MiB)
and sort_bytes (1GiB) parameters allow ~85GB of data to be sorted with two
passes through the data, and ~7.3TB of data to be sorted in three passes
through the data.