statistics_spec.rb in darkhelmet-darkext-0.12.0

- old
+ new

@@ -1,10 +1,12 @@
 require File.dirname(__FILE__) + '/spec_helper'
 
 describe Array do
   before(:each) do
     @a = [1,2,3,4,5,6,7,8,9,10]
+    @hist = [1,2,1,1,3,2,1,1,3,3,3,3,3,2,2,1]
+    @b = [5,1,9,12,6,7,8,8,8,1,2,3,4]
   end
 
   it 'should respond to all the new methods' do
     Array.new.should respond_to(*%w(mean average ave harmonic_mean h_mean geometric_mean g_mean median histogram mode standard_deviation stddev standard_deviation sample ci standardize standardize! sum_of_squares))
     Darkext::Statistics.should respond_to(*%w(prob zscore))
@@ -46,7 +48,115 @@
     lambda { Darkext::Statistics::Regression::least_squares(@a,[1,2,3]) }.should raise_error
   end
 
   it 'should raise an error if either argument has size.zero?' do
     lambda { Darkext::Statistics::Regression::least_squares(@a,Array.new) }.should raise_error
+  end
+
+  it 'should handle mean' do
+    (1..6).to_a.mean.should == 3.5
+    [1].mean.should == 1
+  end
+
+  it 'should handle harmonic mean' do
+    [60,40].harmonic_mean.should be_close(48, 0.0001)
+    [9].harmonic_mean.should be_close(9, 0.0001)
+  end
+
+  it 'should handle geometric mean' do
+    [2,8].geometric_mean.should == 4
+    [9].geometric_mean.should be_close(9, 0.0001)
+  end
+
+  it 'should handle median' do
+    (1..3).to_a.median.should == 2
+    [1].median.should == 1
+    [2,4,6,8].median.should == 5
+  end
+
+  it 'should make histograms' do
+    @hist.histogram.should == { 1 => 6, 2 => 4, 3 => 6 }
+  end
+
+  it 'should handle mode' do
+    @hist.mode.should == [1,3]
+    (@hist + [1]).mode.should == [1]
+  end
+
+  it 'should handle variance' do
+    (1..6).to_a.variance.should be_close(35/12, 0.0001)
+    [1].variance.should be_close(0, 0.0001)
+    [1,1].variance.should be_close(0, 0.0001)
+    @b.variance.should be_close(10.5, 0.05)
+  end
+
+  it 'should handle std dev' do
+    [2,4,4,4,5,5,7,9].stddev.should be_close(2, 0.0001)
+    @b.stddev.should be_close(3.24, 0.01)
+  end
+
+  it 'should sample' do
+    @hist.sample(5).size.should == 5
+  end
+
+  it 'should handle confidence intervals' do
+    ci = @b.ci
+    ci.shift.should be_close(5.15, 0.01)
+    ci.shift.should be_close(6.24, 0.01)
+    @b.ci(:type => :upper).shift.should be_close(6.15, 0.01)
+    @b.ci(:type => :lower).shift.should be_close(5.24, 0.01)
+  end
+
+  it 'should standardize' do
+    [2,2,4,4].standardize.should == [-1,-1,1,1].map(&:to_f)
+    @b.standardize.size.should == 13
+  end
+
+  it 'should do sum of squares' do
+    (1..3).to_a.sum_of_squares.should == 2.0
+  end
+
+  it 'should do probability' do
+    Darkext::Statistics::prob(2).should be_close(0.96, 0.02)
+    Darkext::Statistics::prob(0.5).should be_close(0.69, 0.02)
+    Darkext::Statistics::prob(Darkext::Statistics::zscore(1)).should be_close(1, 0.0001)
+  end
+
+  it 'should do zscore' do
+    Darkext::Statistics::zscore(0.5).should be_close(0, 0.1)
+    Darkext::Statistics::prob(0.75).should be_close(0.77, 0.02)
+    Darkext::Statistics::zscore(Darkext::Statistics::prob(2.5)).should be_close(2.5, 0.0001)
+  end
+
+  it 'should handle regressions' do
+    xs = [0,1.2,2,2.9,4,5,6]
+    ys = [0.1,1,2.1,3,4.3,4.9,6]
+
+    results = Darkext::Statistics::Regression::least_squares(xs,ys)
+
+    results[:n].should == xs.size
+    results[:b_1].should be_close(1, 0.1)
+    results[:b_0].should be_close(0, 0.1)
+    results[:predicted].size.should == xs.size
+
+    results[:predicted].each_with_index do |pred,index|
+      pred.should be_close(index, 0.3)
+    end
+
+    results[:residuals].size.should == xs.size
+
+    results[:residuals].each_with_index do |pred,index|
+      pred.should be_close(0, 0.3)
+    end
+
+    results[:ss_e].should be_close(0.15, 0.01)
+    results[:ss_t].should be_close(27.49, 0.01)
+    results[:estimator].should be_close(0.03, 0.01)
+    results[:r_2].should be_close(1, 0.01)
+    results[:r].should be_close(1, 0.01)
+
+    eqn = results[:equation]
+    (0..100).each do |i|
+      eqn.call(i).should be_close(i, 0.25)
+    end
   end
 end