moved ephem imports to the top of the file

Author: PhilBrk8

pvlib/solarposition.py

@@ -13,6 +13,7 @@
 import warnings
 from importlib import reload
 
+import ephem
 import numpy as np
 import pandas as pd
 import scipy.optimize as so
@@ -484,7 +485,7 @@ def _ephem_to_timezone(date, tzinfo):
 
 def _ephem_setup(latitude, longitude, altitude, pressure, temperature,
                  horizon):
-    import ephem
+    
 
     # initialize a PyEphem observer
     obs = ephem.Observer()
@@ -542,11 +543,6 @@ def sun_rise_set_transit_ephem(times, latitude, longitude,
     pyephem
     """
 
-    try:
-        import ephem
-    except ImportError:
-        raise ImportError('PyEphem must be installed')
-
     # times must be localized
     if times.tz:
         tzinfo = times.tz
@@ -627,12 +623,6 @@ def pyephem(time, latitude, longitude, altitude=0., pressure=101325.,
     spa_python, spa_c, ephemeris
     """
 
-    # Written by Will Holmgren (@wholmgren), University of Arizona, 2014
-    try:
-        import ephem
-    except ImportError:
-        raise ImportError('PyEphem must be installed')
-
     time_utc = tools._pandas_to_utc(time)
 
     sun_coords = pd.DataFrame(index=time)
@@ -933,7 +923,7 @@ def pyephem_earthsun_distance(time):
     pd.Series. Earth-sun distance in AU.
     """
 
-    import ephem
+    
 
     sun = ephem.Sun()
     earthsun = []