kjakub/ruby-standard-deviation

A native extension for Ruby to handle standard deviation for Arrays

Ruby Standard Deviation [reverted before it got yanked from rubygems]

This is a native extension to Ruby that adds a standard deviation calculation to the Array class.

Check the TravisCI build to see the currently supported versions of Ruby. This list will match whatever 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_extension   0.000573	 0.000507	 0.000616	 0.000606	 0.000528
bench_pure_ruby          0.004794	 0.004045	 0.002673	 0.002667	 0.003728

Usage

require 'ruby-standard-deviation'
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 second 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