ruby_native_statistics

Ruby Native Statistics

This is a native extension to Ruby that adds native (Rust) 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)
• Median (median)
• Mean (mean)
• Percentile (percentile)

Check the Github Actions 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 generally more performant than calculating these values with pure Ruby. For a comparison, run the benchmarks with rake benchmark.

Here's the data converted to a Markdown table:

Benchmark (Ruby 3.4.4)	Run 1	Run 2	Run 3	Run 4	Run 5
bench_ruby_median	0.000676	0.000611	0.000619	0.000620	0.000583
bench_native_median	0.000179	0.000167	0.000127	0.000118	0.000188
bench_ruby_stdev	0.000780	0.000767	0.000730	0.000718	0.000733
bench_native_stdev	0.000046	0.000027	0.000034	0.000026	0.000043
bench_ruby_mean	0.000261	0.000240	0.000242	0.000250	0.000241
bench_native_mean	0.000033	0.000023	0.000022	0.000028	0.000022

Found a bug? Need a function?

If you found a bug or need a particular function, please let me know! I work on this gem in my spare time, mainly for learning purposes. Feel free to open a PR or a Github issue and I'll take a look as soon as possible.

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

# calculate sample variance
p r.var

# calculate population variance
p r.varp

# calculate mean
p r.mean

# calculate median
p r.median

# calculate percentile
p r.percentile(0.3333)

Build notes

If you are installing the source vesion of the Gem, be sure to have libclang, e.g. libclang-dev, installed on your system.

Implementation notes

Percentile

Percentile uses the same rounding method as Excel, sometimes called R7.