lib/matrix: intro `Matrix::to_a & transposed`

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>

diff --git a/lib/matrix/matrix.nit b/lib/matrix/matrix.nit
index ab5755d..73131ca 100644 (file)
--- a/lib/matrix/matrix.nit
+++ b/lib/matrix/matrix.nit
@@ -61,6 +61,27 @@ class Matrix
                end
        end
 
+       # Get each row of this matrix in nested arrays
+       #
+       # ~~~
+       # var items = [[1.0, 2.0],
+       #              [3.0, 4.0]]
+       # var matrix = new Matrix.from(items)
+       # assert matrix.to_a == items
+       # ~~~
+       fun to_a: Array[Array[Float]]
+       do
+               var a = new Array[Array[Float]]
+               for j in height.times do
+                       var row = new Array[Float]
+                       for i in width.times do
+                               row.add self[j, i]
+                       end
+                       a.add row
+               end
+               return a
+       end
+
        # Create a matrix from an `Array[Float]` composed of rows after rows
        #
        # Require: `width > 0 and height > 0`
@@ -199,6 +220,25 @@ class Matrix
                return out
        end
 
+       # Get the transpose of this matrix
+       #
+       # ~~~
+       # var matrix = new Matrix.from([[1.0, 2.0, 3.0],
+       #                               [4.0, 5.0, 6.0]])
+       # assert matrix.transposed.to_a == [[1.0, 4.0],
+       #                                   [2.0, 5.0],
+       #                                   [3.0, 6.0]]
+       #
+       # var i = new Matrix.identity(3)
+       # assert i.transposed == i
+       # ~~~
+       fun transposed: Matrix
+       do
+               var out = new Matrix(height, width)
+               for k, v in self do out[k.x, k.y] = v
+               return out
+       end
+
        # Iterate over the values in this matrix
        fun iterator: MapIterator[MatrixCoordinate, Float] do return new MatrixIndexIterator(self)