Enumerable::Statistics provides some methods to calculate statistical summary in arrays and enumerables.

Add this line to your application's Gemfile:

gem 'enumerable-statistics'

And then execute:

$ bundle 

Or install it yourself as:

$ gem install enumerable-statistics 

You should load this library by the following line in your script at first.

require 'enumerable/statistics'

The following methods are supplied by this library:

• Array#mean, Enumerable#mean
  • Calculates a mean of values in an array or an enumerable
• Array#variance, Enumerable#variance
  • Calculates a variance of values in an array or an enumerable
• Array#stdev, Enumerable#stdev
  • Calculates a standard deviation of values in an array or an enumerable
• Array#mean_variance, Enumerable#mean_variance
  • Calculates a mean and a variance simultaneously
• Array#mean_stdev, Enumerable#mean_stdev
  • Calculates a mean and a standard deviation simultaneously
• Array#median
  • Calculates a median of values in an array
• Array#percentile(q)
  • Calculates a percentile or percentiles of values in an array
• Array#value_counts, Enumerable#value_counts, and Hash#value_counts
  • Count how many items for each value in the container
• Array#histogram
  • Calculate histogram of the values in the array

Moreover, for Ruby < 2.4, Array#sum and Enumerable#sum are provided.

All methods scan a collection once to calculate statistics and preserve precision as possible.

$ bundle exec rake bench # sum Warming up -------------------------------------- inject 1.545k i/100ms while 2.342k i/100ms sum 11.009k i/100ms Calculating ------------------------------------- inject 15.016k (± 9.6%) i/s - 75.705k in 5.098723s while 22.238k (±16.2%) i/s - 107.732k in 5.068156s sum 112.992k (± 6.9%) i/s - 572.468k in 5.091868s # mean Warming up -------------------------------------- inject 1.578k i/100ms while 2.057k i/100ms mean 9.855k i/100ms Calculating ------------------------------------- inject 15.347k (± 8.6%) i/s - 77.322k in 5.076009s while 21.669k (±14.5%) i/s - 106.964k in 5.074312s mean 108.861k (± 8.9%) i/s - 542.025k in 5.021786s # variance Warming up -------------------------------------- inject 586.000 i/100ms while 826.000 i/100ms variance 8.475k i/100ms Calculating ------------------------------------- inject 6.187k (± 6.7%) i/s - 31.058k in 5.043418s while 8.597k (± 7.4%) i/s - 42.952k in 5.024587s variance 84.702k (± 8.5%) i/s - 423.750k in 5.039936s 

After checking out the repo, run bin/setup to install dependencies. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/red-data-tools/enumerable-statistics.