FIX: shape adjustment in waverec should not assume a transform along axis 0

test case added.  closes gh-293

Author: grlee77

pywt/_multilevel.py

@@ -142,8 +142,11 @@ def waverec(coeffs, wavelet, mode='symmetric', axis=-1):
     a, ds = coeffs[0], coeffs[1:]
 
     for d in ds:
-        if (a is not None) and (d is not None) and (len(a) == len(d) + 1):
-            a = a[:-1]
+        if (a is not None) and (d is not None):
+            if a.shape[axis] == d.shape[axis] + 1:
+                a = a[[slice(s) for s in d.shape]]
+            elif a.shape[axis] != d.shape[axis]:
+                raise RuntimeError("coefficient shape mismatch")
         a = idwt(a, d, wavelet, mode, axis)
 
     return a

pywt/tests/test_multilevel.py

@@ -486,6 +486,16 @@ def test_waverec_axes_subsets():
         assert_allclose(rec, data, atol=1e-14)
 
 
+def test_waverec_axis_db2():
+    """test for fix to issue gh-293"""
+    rstate = np.random.RandomState(0)
+    data = rstate.standard_normal((16, 16))
+    for axis in [0, 1]:
+        coefs = pywt.wavedec(data, 'db2', axis=axis)
+        rec = pywt.waverec(coefs, 'db2', axis=axis)
+        assert_allclose(rec, data, atol=1e-14)
+
+
 def test_waverec2_axes_subsets():
     rstate = np.random.RandomState(0)
     data = rstate.standard_normal((8, 8, 8))