Second requirement in if statement

z_0 is only converted to np.array is it is a pd.Series (and v_wind is
np.array). z_0 does not have to be converted if it is float or np.array.

Author: SabineHaas

windpowerlib/wind_speed.py

@@ -8,6 +8,7 @@
 __license__ = "GPLv3"
 
 import numpy as np
+import pandas as pd
 
 
 def logarithmic_wind_profile(v_wind, v_wind_height, hub_height, z_0,
@@ -79,7 +80,7 @@ def logarithmic_wind_profile(v_wind, v_wind_height, hub_height, z_0,
                          obstacle_height) + " into consideration, wind" +
                          " speed data of a greater height is needed.")
     # Return np.array if v_wind is np.array
-    if isinstance(v_wind, np.ndarray):
+    if (isinstance(v_wind, np.ndarray) and isinstance(z_0, pd.Series)):
         z_0 = np.array(z_0)
     return (v_wind * np.log((hub_height - 0.7 * obstacle_height) / z_0) /
             np.log((v_wind_height - 0.7 * obstacle_height) / z_0))
@@ -153,7 +154,7 @@ def v_wind_hellman(v_wind, v_wind_height, hub_height, z_0=None,
     if hellman_exp is None:
         if z_0 is not None:
             # Return np.array if v_wind is np.array
-            if isinstance(v_wind, np.ndarray):
+            if (isinstance(v_wind, np.ndarray) and isinstance(z_0, pd.Series)):
                 z_0 = np.array(z_0)
             hellman_exp = 1 / np.log(hub_height / z_0)
         else: