HistogramTools (version 0.3.2)

as.histogram: Convert histogram protocol buffers to histogram objects

Description

This package provides a number of utility functions useful for manipulating large histograms. It provides a ‘HistogramTools.HistogramState’ protocol buffer representation of the default R histogram class to allow histograms to be very concisely serialized and shared with other systems in a distributed MapReduce environment. It also includes a number of utility functions for manipulating large histograms.

Usage

"as.histogram"(x, ...)

Arguments

x

An RProtoBuf Message of type "HistogramTools.HistogramState" to convert to a histogram object.

...

Not used.

Details

as.histogram reads the provided Protocol Buffer message and extracts the buckets and counts to populate into the standard R histogram class which can be plotted.

See Also

histogramtools-package, as.Message, and RProtoBuf.

Examples

  if(require(RProtoBuf)) {
  library(HistogramTools)

  tmp.hist <- hist(c(1,2,4,43,20,33,1,1,3), plot=FALSE)
  # The default R serialization takes a fair number of bytes
  length(serialize(tmp.hist, NULL))

  # Convert to a protocol buffer representation.
  hist.msg <- as.Message(tmp.hist)

  # Which has an ASCII representation like this:
  cat(as.character(hist.msg))

  # Or can be serialized and shared with other tools much more
  # succinctly than R's built-in serialization format.
  length(hist.msg$serialize(NULL))

  # And since this isn't even compressed, we can reduce it further
  # with in-memory compression:
  length(memCompress(hist.msg$serialize(NULL)))

  # If we read in the raw.bytes from another tool
  raw.bytes <- hist.msg$serialize(NULL)

  # We can parse the raw bytes as a protocol buffer
  new.hist.proto <- P("HistogramTools.HistogramState")$read(raw.bytes)
  new.hist.proto

  # Then convert back to a native R histogram.
  new.hist <- as.histogram(new.hist.proto)

  # The new histogram and the old are identical except for xname
  }