lib/matrix_extensions.rb in matrix_extensions-0.0.3 vs lib/matrix_extensions.rb in matrix_extensions-0.0.4

@@ -71,42 +71,39 @@
 
     # create new matrix
     self.rows(rows)
   end
   
-  # Removes trailing columns from a Matrix.
+  # Removes trailing columns from a Matrix (destructive).
   # @param number_of_columns [Integer] number of trailing columns to be removed
-  # @return [Matrix] matrix
+  # @return [Matrix] matrix consisting of of dropped columns
   # @raise [ErrDimensionMismatch] if Matrix does not have enough columns for operation
   def hpop(number_of_columns = 1)        
     Matrix.Raise ErrDimensionMismatch unless number_of_columns < self.column_count
 
-    columns = []
-    last_column_to_be_included = self.column_count - number_of_columns
-    self.column_vectors.each_with_index do |column, index|
-      break if index + 1 > last_column_to_be_included
-      columns << column.to_a
+    dropped_columns = []
+    number_of_columns.times do
+      dropped_column = []      
+      @rows.each {|r| dropped_column << r.pop}
+      dropped_columns << dropped_column
     end
-    
-    Matrix.columns(columns)       
+    @column_count -= number_of_columns
+
+    Matrix.columns(dropped_columns.reverse)
   end
 
-  # Removes trailing rows from a Matrix.
+  # Removes trailing rows from a Matrix (destructive).
   # @param number_of_rows [Integer] number of trailing rows to be removed
-  # @return [Matrix] matrix
+  # @return [Matrix] matrix consisting of of dropped rows
   # @raise [ErrDimensionMismatch] if Matrix does not have enough rows for operation
   def vpop(number_of_rows = 1)        
     Matrix.Raise ErrDimensionMismatch unless number_of_rows < self.row_count
 
-    rows = []
-    last_row_to_be_included = self.row_count - number_of_rows
-    self.row_vectors.each_with_index do |row, index|
-      break if index + 1 > last_row_to_be_included
-      rows << row.to_a
-    end
-    
-    Matrix.rows(rows)       
-  end  
+    dropped_rows = []    
+    number_of_rows.times { dropped_rows.unshift @rows.pop }
+
+    Matrix.rows(dropped_rows.reverse)      
+  end 
 
   # Element-wise division.
   # @param m [Matrix] matrix
   # @return [Matrix] matrix
   # @raise [ErrDimensionMismatch] if dimensions don't match
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