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# orch.pack

Compresses one or more in-memory R objects that the mappers or reducers must write as the values in key-value pairs.

Usage

    orch.pack(...)

Arguments

. . .

  One or more variables, data frames, or other in-memory objects in a comma-separated list.

Usage Notes

You should use this function when passing nonscalar or complex R objects, such as data frames and R classes, between the mapper and reducer functions. You do not need to use it on scalar or other simple objects. You can use `orch.pack` to vary the data formats, data sets, and variable names for each output value.

You should also use `orch.pack` when storing the resultant data set in HDFS. The compressed data set is not corrupted by being stored in an HDFS file.

The `orch.pack` function must always be followed by the `orch.unpack` function to restore the data to a usable format.

Return Value

Compressed character-type data as a long string with no special characters

See Also

`hadoop.exec`, `hadoop.run`, `orch.keyval`, `orch.unpack`

Example

This code fragment compresses the content of several R objects into a serialized stream using `orch.pack`, and then creates key-value pairs using `orch.keyval`:

    orch.keyval(NULL, orch.pack(
         r = r,
         qy = qy,
         yy = yy,
         nRows = nRows))