BUG: Unable to delete row from lil matrix after scalar multiplication (…

…closes #1427).
scipy · Nov 2, 2011 · 7cdfb34 · 7cdfb34
1 parent 84c4247
commit 7cdfb34
Show file tree

Hide file tree

Showing 2 changed files with 9 additions and 4 deletions.
diff --git a/scipy/sparse/lil.py b/scipy/sparse/lil.py
@@ -359,16 +359,16 @@ def _mul_scalar(self, other):
         else:
             new = self.copy()
             # Multiply this scalar by every element.
-            new.data = np.array([[val*other for val in rowvals] for
-                                  rowvals in new.data], dtype=object)
+            new.data[:] = [[val*other for val in rowvals] for
+                           rowvals in new.data]
         return new
 
     def __truediv__(self, other):           # self / other
         if isscalarlike(other):
             new = self.copy()
             # Divide every element by this scalar
-            new.data = np.array([[val/other for val in rowvals] for
-                                  rowvals in new.data], dtype=object)
+            new.data = [[val/other for val in rowvals] for
+                        rowvals in new.data]
             return new
         else:
             return self.tocsr() / other

diff --git a/scipy/sparse/tests/test_base.py b/scipy/sparse/tests/test_base.py
@@ -1500,6 +1500,11 @@ def test_point_wise_multiply(self):
                             [0,0,9],
                             [0,16,0]])
 
+    def test_lil_multiply_removal(self):
+        """Ticket #1427."""
+        a = lil_matrix(np.ones((3,3)))
+        a *= 2.
+        a[0, :] = 0
 
 
 class TestCOO(_TestCommon, TestCase):