make Zeropadder more flexible

nifty5/operators/field_zero_padder.py

@@ -41,8 +41,8 @@ class FieldZeroPadder(LinearOperator):
 
         if len(new_shape) != len(dom.shape):
             raise ValueError("Shape mismatch")
-        if any([a <= b for a, b in zip(new_shape, dom.shape)]):
-            raise ValueError("New shape must be larger than old shape")
+        if any([a < b for a, b in zip(new_shape, dom.shape)]):
+            raise ValueError("New shape must not be smaller than old shape")
         self._target = list(self._domain)
         self._target[self._space] = RGSpace(new_shape, dom.distances)
         self._target = DomainTuple.make(self._target)
@@ -54,6 +54,9 @@ class FieldZeroPadder(LinearOperator):
         curshp = list(self._dom(mode).shape)
         tgtshp = self._tgt(mode).shape
         for d in self._target.axes[self._space]:
+            if v.shape[d] == tgtshp[d]:  # nothing to do
+                continue
+
             idx = (slice(None),) * d
 
             v, x = dobj.ensure_not_distributed(v, (d,))

test/test_operators/test_adjoint.py

@@ -209,7 +209,7 @@ class Consistency_Tests(unittest.TestCase):
         op = ift.SymmetrizingOperator(dom, space)
         ift.extra.consistency_check(op, dtype, dtype)
 
-    @expand(product([0, 2], [2, 2.7], [np.float64, np.complex128],
+    @expand(product([0, 2], [1, 2, 2.7], [np.float64, np.complex128],
                     [False, True]))
     def testZeroPadder(self, space, factor, dtype, central):
         dom = (ift.RGSpace(10), ift.UnstructuredDomain(13), ift.RGSpace(7, 12),