Sync

Task/Identity-matrix/Python/identity-matrix-1.py

@@ -1,5 +1,6 @@
 def identity(size):
-    matrix = [[0] * size] * size
+    matrix = [[0]*size for i in range(size)]
+    #matrix = [[0] * size] * size    #Has a flaw. See http://stackoverflow.com/questions/240178/unexpected-feature-in-a-python-list-of-lists
 
     for i in range(size):
         matrix[i][i] = 1

Task/Identity-matrix/Python/identity-matrix-2.py

@@ -1 +1,11 @@
-np.mat(np.eye(size))
+>>> def identity(size):
+...     return {(x, y):int(x == y) for x in range(size) for y in range(size)}
+...
+>>> size = 4
+>>> matrix = identity(size)
+>>> print('\n'.join(' '.join(str(matrix[(x, y)]) for x in range(size)) for y in range(size)))
+1 0 0 0
+0 1 0 0
+0 0 1 0
+0 0 0 1
+>>>

Task/Identity-matrix/Python/identity-matrix-3.py

@@ -0,0 +1 @@
+np.mat(np.eye(size))