147 lines
2.9 KiB
Markdown
147 lines
2.9 KiB
Markdown
**Migrated to <https://git.sceptique.eu/Sceptique/stats>**
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# stats
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An expressive implementation of statistical distributions.
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Compatible with crystal v0.27.0.
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## Installation
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Add this to your application's `shard.yml`:
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```yaml
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dependencies:
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stats:
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git: https://git.sceptique.eu/Sceptique/stats
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```
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## Usage
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### Include it
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```crystal
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require "stats"
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include Stats
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```
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### Normal distribution
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```crystal
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NormaleDistribution.between # less_than, greater_than
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standard_deviation: 15,
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esperance: 100,
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min: 85,
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max: 115
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# => 0.6826894921370859
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```
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### Binomial distribution
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```crystal
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Math.binomial_distribution(
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tries: 3,
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probability: 0.5,
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success: 1)
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# => 0.375
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```
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### Binomial coefficient
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```crystal
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Math.coef_binomial(5, 2) # => 10
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```
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### Factorial
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```crystal
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Math.factorial(4) # => 24
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```
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### Radian and degree
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```crystal
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90.radian # => (Math::PI / 2)
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(Math::PI / 4) # => 45.0
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```
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### Series & Statistics
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```crystal
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[1, 2, 3].mean # => 2.0
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[1, 2, 3].variance # => 0.6667
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[1, 2, 3].standard_deviation # => 0.8165
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[1, 2, 3].quadratic_mean # => 2.16
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[2, 32].geometric_mean # => 8.0
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[40, 60].harmonic_mean # => 48.0
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[1,2,3,2,1].macd 3 # => [2.0, 2.333, 2.0]
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```
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### Correlations
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```crystal
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[1,2,3,4].covariance [4,2,1,0] # => -1.625
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[1,2,3,4].correlation_coef [1,2,3,3] + 1 > 1.5 # => true
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[1,2,3,4].correlation_coef [-14,14,101,-100] + 1 > 1.5 # => false
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```
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### Median
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```crystal
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[1, 2, 5].median # => 2.0
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[42, 1337].median # => 685.5
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```
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### Quartiles & Boxplot
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*Note: not big compatible yet*
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```crystal
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[1, 3, 5].first_quartile # => 2.0 (alias of lower_quartile)
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[1, 3, 5].second_quartile # => 3.0 (alias of median)
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[1, 3, 5].third_quartile # => 4.0 (alias of upper_quartile)
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[1, 3, 5].quartiles # => [2.0, 3.0, 4.0] ([Q1, Q2, Q3])
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```
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```crystal
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arr = [-23, -5, 2, 5, 5, 6, 7, 8, 14, 15, 42, 1337]
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arr.first_quartile # => 3.5 (Q1)
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arr.second_quartile # => 6.5 (Q2)
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arr.third_quartile # => 14.5 (Q3)
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arr.interquartile_range # => 11.0 (alias of iqr) (IQR = Q3 - Q1)
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# Tukey's fences with k = 1.5 (default parameter value)
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arr.lower_fence # => -13.0 (Q1 - 1.5 * IQR)
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arr.upper_fence # => 31 (Q3 + 1.5 * IQR)
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arr.lower_outliers # => [-23]
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arr.upper_outliers # => [42, 1337]
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# Tukey's fences with k = 3 for "far out" outliers
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arr.upper_fence(3) # => 47.5 (Q3 + 3 * IQR)
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arr.upper_outliers(3) # => [1337]
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```
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### Frequency
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```crystal
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[0, 1, 2, 3].frequency_of(0) # => 0.25 (amount of X in the population, by the size of the population)
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[0, 0, 1, 2, 3].all_frequencies # => { 0 => 0.4, 1 => 0.2, 2 => 0.2, 3 => 0.2}
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```
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## Development
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- The lib should take care of "big" numbers
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## Contributing
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1. Fork it ( https://github.com/Nephos/stats/fork )
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2. Create your feature branch (git checkout -b my-new-feature)
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3. Commit your changes (git commit -am 'Add some feature')
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4. Push to the branch (git push origin my-new-feature)
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5. Create a new Pull Request
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## Contributors
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- [Nephos](https://github.com/Nephos) Arthur Poulet - creator, maintainer
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