Make identity function faster. Closes ticket #1193.

1 files changed, 3 insertions, 9 deletions

diff --git a/numpy/core/numeric.py b/numpy/core/numeric.py
index 31b021b71..c961bcc0f 100644
--- a/numpy/core/numeric.py
+++ b/numpy/core/numeric.py
@@ -1692,15 +1692,9 @@ def identity(n, dtype=None):
            [ 0.,  0.,  1.]])
 
     """
-    a = array([1]+n*[0],dtype=dtype)
-    b = empty((n,n),dtype=dtype)
-
-    # Note that this assignment depends on the convention that since the a
-    # array is shorter than the flattened b array, then the a array will
-    # be repeated until it is the appropriate size. Given a's construction,
-    # this nicely sets the diagonal to all ones.
-    b.flat = a
-    return b
+    a = zeros((n,n), dtype=dtype)
+    a.flat[::n+1] = 1
+    return a
 
 def allclose(a, b, rtol=1.e-5, atol=1.e-8):
     """