ENH: Allow "isclose()" to work with subclasses of ndarray (such as masked arrays).

1 files changed, 11 insertions, 6 deletions

diff --git a/numpy/core/numeric.py b/numpy/core/numeric.py
index 60111e1f2..e4693431c 100644
--- a/numpy/core/numeric.py
+++ b/numpy/core/numeric.py
@@ -2086,19 +2086,24 @@ def isclose(a, b, rtol=1.e-5, atol=1.e-8, equal_nan=False):
         if isscalar(a) and isscalar(b):
             result = bool(result)
         return result
-    x = array(a, copy=False, ndmin=1)
-    y = array(b, copy=False, ndmin=1)
+    x = array(a, copy=False, subok=True, ndmin=1)
+    y = array(b, copy=False, subok=True, ndmin=1)
     xfin = isfinite(x)
     yfin = isfinite(y)
     if all(xfin) and all(yfin):
         return within_tol(x, y, atol, rtol)
     else:
+        finite = xfin & yfin
+        # Because we're using boolean indexing, x & y must be the same shape.
+        # Ideally, we'd just do x, y = broadcast_arrays(x, y). It's in
+        # lib.stride_tricks, though, so we can't import it here.
+        cond = zeros_like(finite, subok=True)
+        x = x * ones_like(cond)
+        y = y * ones_like(cond)
         # Avoid subtraction with infinite/nan values...
-        cond = zeros(broadcast(x, y).shape, dtype=bool)
-        mask = xfin & yfin
-        cond[mask] = within_tol(x[mask], y[mask], atol, rtol)
+        cond[finite] = within_tol(x[finite], y[finite], atol, rtol)
         # Check for equality of infinite values...
-        cond[~mask] = (x[~mask] == y[~mask])
+        cond[~finite] = (x[~finite] == y[~finite])
         if equal_nan:
             # Make NaN == NaN
             cond[isnan(x) & isnan(y)] = True