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)
- 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.
| Test (Ruby 3.3.0) | Run 1 | Run 2 | Run 3 | Run 4 | Run 5 |
|---|---|---|---|---|---|
| bench_native_stdev | 0.000069 | 0.000074 | 0.000064 | 0.000065 | 0.000065 |
| bench_ruby_stdev | 0.000947 | 0.000932 | 0.000927 | 0.000948 | 0.000909 |
| Test (Ruby 3.3.0) | Run 1 | Run 2 | Run 3 | Run 4 | Run 5 |
|---|---|---|---|---|---|
| bench_native_median | 0.000719 | 0.00067 | 0.000659 | 0.000638 | 0.000668 |
| bench_ruby_median | 0.000774 | 0.000743 | 0.000724 | 0.000697 | 0.000683 |
| Test (Ruby 3.3.0) | Run 1 | Run 2 | Run 3 | Run 4 | Run 5 |
|---|---|---|---|---|---|
| bench_native_mean | 0.000035 | 0.000035 | 0.000034 | 0.000032 | 0.000033 |
| bench_ruby_mean | 0.000291 | 0.000287 | 0.000291 | 0.000299 | 0.000281 |
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.
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 mean
p r.mean
# calculate median
p r.median
# calculate percentile
p r.percentile(0.3333)
Percentile uses the same rounding method as Excel, sometimes called R7.
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: