Class: Array

Inherits:
Object
  • Object
show all
Defined in:
lib/stella/core_ext.rb,
lib/stella/core_ext.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.from_json(str) ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 443

def self.from_json(str)
  Yajl::Parser.parse(str, :check_utf8 => false)
end

Instance Method Details

#deviation ⇒ Object Also known as: sd 



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# File 'lib/stella/core_ext.rb', line 413

def deviation ; Math::sqrt( self.variance ) ; end

#dump(format) ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 436

def dump(format)
  respond_to?(:"to_#{format}") ? send(:"to_#{format}") : raise("Unknown format: #{format}")
end

#histogram ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 405

def histogram ; self.sort.inject({}){|a,x|a[x]=a[x].to_i+1;a} ; end

#mean ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 398

def mean; self.sum.to_f/self.size ; end

#median ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 399

def median
  case self.size % 2
    when 0 then self.sort[self.size/2-1,2].mean
    when 1 then self.sort[self.size/2].to_f
  end if self.size > 0
end

#mode ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 406

def mode
  map = self.histogram
  max = map.values.max
  map.keys.select{|x|map[x]==max}
end

#percentile(perc) ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 426

def percentile(perc)
  self.sort[percentile_index(perc)]
end

#percentile_index(perc) ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 429

def percentile_index(perc)
  (perc * self.length).ceil - 1
end

#permute ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 415

def permute ; self.dup.permute! ; end

#permute! ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 416

def permute!
  (1...self.size).each do |i| ; j=rand(i+1)
    self[i],self[j] = self[j],self[i] if i!=j
  end;self
end

#random ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 423

def random
  self[rand(self.size)]
end

#sample(n = 1) ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 421

def sample n=1 ; (0...n).collect{ self[rand(self.size)] } ; end

#squares ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 411

def squares ; self.inject(0){|a,x|x.square+a} ; end

#sum ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 397

def sum ; self.inject(0){|a,x| next if x.nil? || a.nil?; x+a} ; end

#to_json ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 440

def to_json
  Yajl::Encoder.encode(self)
end

#variance ⇒ Object 



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# File 'lib/stella/core_ext.rb', line 412

def variance ; self.squares.to_f/self.size - self.mean.square; end