* lib/matrix.rb: Add hstack & vstack methods.

  Based on a patch by creasywuqiong. [Fix GH-344]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47769 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 73 insertions, 0 deletions

diff --git a/lib/matrix.rb b/lib/matrix.rb
index 45c24d1275..81834ab898 100644
--- a/lib/matrix.rb
+++ b/lib/matrix.rb
@@ -45,6 +45,8 @@ end
 # * Matrix.zero(n)
 # * Matrix.row_vector(row)
 # * Matrix.column_vector(column)
+# * Matrix.hstack(*matrices)
+# * Matrix.vstack(*matrices)
 #
 # To access Matrix elements/columns/rows/submatrices/properties:
 # * #[](i, j)
@@ -90,12 +92,14 @@ end
 # Matrix functions:
 # * #determinant
 # * #det
+# * #hstack(*matrices)
 # * #rank
 # * #round
 # * #trace
 # * #tr
 # * #transpose
 # * #t
+# * #vstack(*matrices)
 #
 # Matrix decompositions:
 # * #eigen
@@ -296,6 +300,51 @@ class Matrix
   end
 
   #
+  # Create a matrix by stacking matrices vertically
+  #
+  #   x = Matrix[[1, 2], [3, 4]]
+  #   y = Matrix[[5, 6], [7, 8]]
+  #   Matrix.vstack(x, y) # => Matrix[[1, 2], [3, 4], [5, 6], [7, 8]]
+  #
+  def Matrix.vstack(x, *matrices)
+    raise TypeError, "Expected a Matrix, got a #{x.class}" unless x.is_a?(Matrix)
+    result = x.send(:rows).map(&:dup)
+    matrices.each do |m|
+      raise TypeError, "Expected a Matrix, got a #{m.class}" unless m.is_a?(Matrix)
+      if m.column_count != x.column_count
+        raise ErrDimensionMismatch, "The given matrices must have #{x.column_count} columns, but one has #{m.column_count}"
+      end
+      result.concat(m.send(:rows))
+    end
+    new result, x.column_count
+  end
+
+
+  #
+  # Create a matrix by stacking matrices horizontally
+  #
+  #   x = Matrix[[1, 2], [3, 4]]
+  #   y = Matrix[[5, 6], [7, 8]]
+  #   Matrix.hstack(x, y) # => Matrix[[1, 2, 5, 6], [3, 4, 7, 8]]
+  #
+  def Matrix.hstack(x, *matrices)
+    raise TypeError, "Expected a Matrix, got a #{x.class}" unless x.is_a?(Matrix)
+    result = x.send(:rows).map(&:dup)
+    total_column_count = x.column_count
+    matrices.each do |m|
+      raise TypeError, "Expected a Matrix, got a #{m.class}" unless m.is_a?(Matrix)
+      if m.row_count != x.row_count
+        raise ErrDimensionMismatch, "The given matrices must have #{x.row_count} rows, but one has #{m.row_count}"
+      end
+      result.each_with_index do |row, i|
+        row.concat m.send(:rows)[i]
+      end
+      total_column_count += m.column_count
+    end
+    new result, total_column_count
+  end
+
+  #
   # Matrix.new is private; use Matrix.rows, columns, [], etc... to create.
   #
   def initialize(rows, column_count = rows[0].size)
@@ -1143,6 +1192,18 @@ class Matrix
   alias det_e determinant_e
 
   #
+  # Returns a new matrix resulting by stacking horizontally
+  # the receiver with the given matrices
+  #
+  #   x = Matrix[[1, 2], [3, 4]]
+  #   y = Matrix[[5, 6], [7, 8]]
+  #   x.hstack(y) # => Matrix[[1, 2, 5, 6], [3, 4, 7, 8]]
+  #
+  def hstack(*matrices)
+    self.class.hstack(self, *matrices)
+  end
+
+  #
   # Returns the rank of the matrix.
   # Beware that using Float values can yield erroneous results
   # because of their lack of precision.
@@ -1223,6 +1284,18 @@ class Matrix
   end
   alias t transpose
 
+  #
+  # Returns a new matrix resulting by stacking vertically
+  # the receiver with the given matrices
+  #
+  #   x = Matrix[[1, 2], [3, 4]]
+  #   y = Matrix[[5, 6], [7, 8]]
+  #   x.vstack(y) # => Matrix[[1, 2], [3, 4], [5, 6], [7, 8]]
+  #
+  def vstack(*matrices)
+    self.class.vstack(self, *matrices)
+  end
+
   #--
   # DECOMPOSITIONS -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
   #++