Measurable
This gem encompasses various distance measures. Besides the Array class, I also want to support NMatrix's NVector.
My objective is to be able to compare different metrics just by changing which method is called. Also, to show how to use NMatrix's C API. I'll create most of the things in pure Ruby first, then the most used operations (or the slowest ones) will be rewritten in C.
This is a fork of the gem Distance Measure, which has a similar objective, but isn't actively maintained and doesn't support NMatrix. Thank you, reddavis. :)
Install
gem install measurable
It only works with Ruby MRI 1.9.3 or 2.0.0. I still want to test it on JRuby, but as its still pure Ruby, it should work correctly there.
Distance measures that I want to support for the moment
- Euclidean distance
- Squared euclidean distance
- Cosine distance
- Max-min distance ("K-Means clustering using max-min distance measure")
- Jaccard distance
- Tanimoto distance
These still need to be implemented:
- Cityblock distance
- Chebyshev distance
- Minkowski distance
- Hamming distance
- Correlation distance
- Chi-square distance
- Kullback-Leibler divergence
- Jensen-Shannon divergence
- Mahalanobis distance
- Squared Mahalanobis distance
How to use
This list will be updated as I have time. I'll refactor the existing measures and add some that I'll need in a project.
The API I intend to support is something like this:
require "measurable"
u = NVector.ones(2)
v = NVector.zeros(2)
w = [1, 0]
x = [2, 2]
Measurable::euclidean(u, v) # => 1.41421
Measurable::euclidean(w, v) # => 1.00000
Measurable::euclidean(w, w) # => 0.00000
Measurable::
Maybe add support for (some of) NMatrix's dtypes, like :float32, :float64, :complex64, :complex128, etc. This will have to way until Measurable supports NMatrix C API.
License
See LICENSE for details.
The original Distance Measure gem is copyrighted by @reddavis.