apply-dMatrix-method: Apply function for 'rDMatrix' or 'cDMatrix' objects.
In gdlc/dMatrix: Memory Mapped Matrices and Data Structures for Genomic Data

This function brings chunks of data (of size chunkSize) from the distributed array into RAM as matrix objects and calls apply of the base package to obtain the summaries for the chunk. Results from all the chunks are collected and returned.

1
2
3

## S4 method for signature 'dMatrix'
apply(X, MARGIN, FUN, chunkSize = 1000, verbose = TRUE,
  ...)

`X`	Either an `rDMatrix` or a `cDMatrix` object.
`MARGIN`	Use 1 to obtain row summaries or 2 to obtain column summaries.
`chunkSize`	The number of columns or rows that are processed at a time (see Details).