FIX: Fix interpolation of dpss_windows

nitime/algorithms/spectral.py

@@ -419,8 +419,7 @@ def dpss_windows(N, NW, Kmax, interp_from=None, interp_kind='linear'):
         for this_d in d:
             x = np.arange(this_d.shape[-1])
             I = interpolate.interp1d(x, this_d, kind=interp_kind)
-            d_temp = I(np.arange(0, this_d.shape[-1] - 1,
-                                 float(this_d.shape[-1] - 1) / N))
+            d_temp = I(np.linspace(0, this_d.shape[-1] - 1, N, endpoint=False))
 
             # Rescale:
             d_temp = d_temp / np.sqrt(np.sum(d_temp ** 2))

nitime/algorithms/tests/test_spectral.py

@@ -157,7 +157,7 @@ def test_periodogram_csd():
 
 
 def test_dpss_windows():
-    """ Test a funky corner case of DPSS_windows """
+    """ Test a couple of funky corner cases of DPSS_windows """
 
     N = 1024
     NW = 0  # Setting NW to 0 triggers the weird corner case in which some of
@@ -169,6 +169,11 @@ def test_dpss_windows():
     for this_d in d[0::2]:
         npt.assert_equal(this_d.sum(axis=-1) < 0, False)
 
+    # Make sure we interpolate to the proper number of points
+    d, w = tsa.dpss_windows(245411, 4, 8, 1000)
+    npt.assert_equal(d.shape[-1], 245411)
+
+
 def test_dpss_properties():
     """ Test conventions of Slepian eigenvectors """