Added axis option. Useful for future interpolation of data.

lib/sequel_vectorized.rb

@@ -1,9 +1,10 @@
 require 'narray'
 
 class Sequel::Dataset
-  def vectorize 
+  def vectorize options={}
 
     result = {}
+    axis = options[:axis]
 
     # transform dataset to hash of arrays
     map {|row| row.each{|att,value| (result[att] ||= []) << value}}
@@ -24,6 +25,31 @@ def vectorize
         result[k][] = v.map {|i| (i == true) ? 1 : 0 }
 
       end
+
     end
+
+    axis ? _process(result, axis) : result
+
   end
+
+  private
+  def _process data, axis
+    column = axis[:column]
+    range = axis[:range]
+    step = axis[:step]
+
+    data_places = data[column]/step.to_f - range.first/step.to_f
+    data[column] = NArray.float((range.last - range.first)/step.to_f).indgen!(range.first,60)
+
+    data.each do |k,v|
+      next if k == column 
+      if v.kind_of? NArray and v[0].kind_of? Numeric then
+        data[k] = NArray.float((range.last - range.first)/step.to_f)
+        data[k][data_places] = v
+      end
+    end
+
+    data
+  end
+
 end

spec/sequel_vectorized_spec.rb

@@ -72,4 +72,34 @@
     }
   end
 
+  it "is possible to pass an :axis option" do
+    axis = {
+      :column => :ts,
+      :step => 60,
+      :range => [Time.local(2008,1,1,12).to_f, Time.local(2008,1,1,15).to_f],
+      :interpolate => true
+    }
+
+    lambda {
+      @events.vectorize axis
+    }.should_not raise_error
+  end
+
+  it "returns new narrays of size (range.last-range.first)/step if :axis is given" do
+
+    axis = {
+      :column => :ts,
+      :step => 60,
+      :range => [Time.local(2008,1,1,12).to_f, Time.local(2008,1,1,15).to_f],
+      :interpolate => false
+    }
+
+    ret = @events.vectorize :axis => axis
+
+    ret.should == {
+      :value => NArray.to_na([[0]*30, 2.2, [0]*59, 1.1, [0]*59,3.3, [0]*29].flatten),
+      :ts => NArray.float(180).indgen(Time.local(2008,1,1,12).to_f,60)
+    }
+  end
+
 end