Restores the R objects that were compressed with a previous call to orch.pack
.
This function is typically used at the beginning of a mapper or reducer function to obtain and prepare the input. However, it can also be used externally, such as at the R console, to unpack the results of a MapReduce job.
Consider this data flow:
ORCH
client to mapper to combiner to reducer to ORCH
client.
If the data is packed at one stage, then it must be unpacked at the next stage.
This code fragment restores the data that was compressed in the orch.pack
example:
reducer = function(key, vals) { x <-orch.unpack(vals[[1]]) r <-x$qy yy <- x$yy nRow <- x$nRows . . . }