Fix shear velocity functions

dolfyn/adp/turbulence.py

@@ -65,16 +65,24 @@ def __init__(self, n_bin, fs, n_fft=None, n_fft_coh=None,
         self.diff_style = diff_style
         self.orientation = orientation
 
-    def _diff_func(self, vel, u):
+    def _diff_func(self, vel, u, orientation):
+        if not orientation:
+            orientation = self.orientation
+        sign = 1
+        if orientation == 'down':
+            sign *= -1
+
         if self.diff_style == 'first':
             out = _diffz_first(vel[u].values, vel['range'].values)
-            return out, vel.range[1:]
+            return sign*out, vel.range[1:]
+
         elif self.diff_style == 'centered':
             out = _diffz_centered(vel[u].values, vel['range'].values)
-            return out, vel.range[1:-1]
+            return sign*out, vel.range[1:-1]
+
         elif self.diff_style == 'centered_extended':
             out = _diffz_centered_extended(vel[u].values, vel['range'].values)
-            return out, vel.range
+            return sign*out, vel.range
 
     def calc_dudz(self, vel, orientation=None):
         """The shear in the first velocity component.
@@ -93,21 +101,15 @@ def calc_dudz(self, vel, orientation=None):
         'true vertical' direction.
         """
 
-        if not orientation:
-            orientation = self.orientation
-        sign = 1
-        if orientation == 'down':
-            sign *= -1
-
-        dudz, rng = sign*self._diff_func(vel, 0)
+        dudz, rng = self._diff_func(vel, 0, orientation)
         return xr.DataArray(dudz,
                             coords=[rng, vel.time],
                             dims=['range', 'time'],
                             attrs={'units': 's-1',
                                    'long_name': 'Shear in X-direction'}
                             )
 
-    def calc_dvdz(self, vel):
+    def calc_dvdz(self, vel, orientation=None):
         """The shear in the second velocity component.
 
         Parameters
@@ -122,15 +124,15 @@ def calc_dvdz(self, vel):
         'true vertical' direction.
         """
 
-        dvdz, rng = self._diff_func(vel, 1)
+        dvdz, rng = self._diff_func(vel, 1, orientation)
         return xr.DataArray(dvdz,
                             coords=[rng, vel.time],
                             dims=['range', 'time'],
                             attrs={'units': 's-1',
                                    'long_name': 'Shear in Y-direction'}
                             )
 
-    def calc_dwdz(self, vel):
+    def calc_dwdz(self, vel, orientation=None):
         """The shear in the third velocity component.
 
         Parameters
@@ -144,8 +146,8 @@ def calc_dwdz(self, vel):
         coordinate ('dz' is actually diff(self['range'])), not necessarily the
         'true vertical' direction.
         """
-
-        dwdz, rng = self._diff_func(vel, 2)
+            
+        dwdz, rng = self._diff_func(vel, 2, orientation)
         return xr.DataArray(dwdz,
                             coords=[rng, vel.time],
                             dims=['range', 'time'],