Merge branch 'faster_combined_update' into combined_update

Only merging clearsky_temperature

rdtools/clearsky_temperature.py

@@ -4,6 +4,7 @@
 import math
 import pandas as pd
 import pkg_resources
+import numpy as np
 
 
 def get_clearsky_tamb(times, latitude, longitude, window_size=40, gauss_std=20):
@@ -69,12 +70,12 @@ def get_clearsky_tamb(times, latitude, longitude, window_size=40, gauss_std=20):
 
     def solar_noon_offset(utc_offset):
         return longitude / 180.0 * 12.0 - utc_offset
-    df['solar_noon_offset'] = [solar_noon_offset(utc_offset) for utc_offset in utc_offsets]
+
+    df['solar_noon_offset'] = solar_noon_offset(np.array(utc_offsets))
 
     df['hour_of_day'] = df.index.hour + df.index.minute / 60.0
-    df['Clear Sky Temperature (C)'] = df.apply(lambda x:
-                                               _get_temperature(x['hour_of_day'], x['night'],
-                                                                x['day'], x['solar_noon_offset']), axis=1)
+    df['Clear Sky Temperature (C)'] = _get_temperature(df['hour_of_day'].values, df['night'].values,\
+                                                       df['day'].values, df['solar_noon_offset'].values)
     return df['Clear Sky Temperature (C)']
 
 
@@ -104,6 +105,6 @@ def _get_temperature(hour_of_day, night_temp, day_temp, solar_noon_offset):
     temp_scaler = 0.7
     t_diff = day_temp - night_temp
     t_ave = (day_temp + night_temp) / 2.0
-    v = math.cos((hour_of_day + hour_offset) / 24.0 * 2.0 * math.pi)
+    v = np.cos((hour_of_day + hour_offset) / 24.0 * 2.0 * np.pi)
     t = t_diff * 0.5 * v * temp_scaler + t_ave
     return t