nanosplit/ruby-native-statistics

A set of native extensions for Ruby to handle common statistical operations

Ruby Native Statistics

This is a native extension to Ruby that adds native (C) statistical functions to the Array class. At present the following functions are provided:

• Sample Standard Deviation (stdev, stdevs)
• Population Standard Deviation (stdevp)
• Sample Variance (var)
• Population Variance (varp)

Check the TravisCI build to see the currently supported versions of Ruby. This list will match whatever stable versions are specified at https://www.ruby-lang.org/en/downloads/.

It is much more performant than calculating the standard deviation with pure Ruby. For a comparison, run the benchmarks with rake.

bench_native_dispersion  0.000686  0.000628  0.000595  0.000475  0.000590
bench_ruby_dispersion    0.002630  0.004559  0.002589  0.002909  0.002812

Usage

require 'ruby_native_statistics'
r = [1,3,21,32,42]

# calculate sample standard deviation, you can also use "stdevs"
p r.stdev

# calculate population standard deviation
p r.stdevp

Links

This is the third version of this gem, and it is a total rewrite of a SWIG-based design. Lots of thanks to the following resources:

• https://blog.jcoglan.com/2012/07/29/your-first-ruby-native-extension-c/
• https://github.com/andremedeiros/ruby-c-cheat-sheet
• http://silverhammermba.github.io/emberb/c/
• http://docs.ruby-lang.org/en/2.3.0/extension_rdoc.html