Makes R objects from a user's local R session available in the Hadoop execution environment, so that they can be referenced in MapReduce jobs.
One or more variables, data frames, or other in-memory objects, by name or as an explicit definition, in a comma-separated list.
You can use this function to prepare local variables for use in hadoop.exec
and hadoop.run
functions. The mapper
, reducer
, combiner
, init
, and final
arguments can reference the exported variables.
This code fragment shows orch.export
used in the export
argument of the hadoop.run
function:
hadoop.run(x, export = orch.export(a=1, b=2), mapper = function(k,v) { x <- a + b orch.keyval(key=NULL, val=x) } )
The following is a similar code fragment, except that the variables are defined outside the hadoop.run
function:
a=1 b=2 hadoop.run(x, export = orch.export(a, b), . . . )