histogram-message: Convert histogram protocol buffers to histogram objects

In HistogramTools: Utility Functions for R Histograms

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

  ## S3 method for class 'Message'
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.

Author(s)

Murray Stokely [e-mail]

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
  }

Example output

Loading required package: RProtoBuf
breaks: 0
breaks: 10
breaks: 20
breaks: 30
breaks: 40
breaks: 50
counts: 6
counts: 1
counts: 0
counts: 1
counts: 1
name: "c(1, 2, 4, 43, 20, 33, 1, 1, 3)"

HistogramTools documentation built on May 2, 2019, 1:08 p.m.