New App; stable_night_lights

With this merge toar-location-services can provide stable night light data.

Furthermore, there are test functions added to check, if an import routine works properly. (for apps: population-density, stable_night_lights and topography-tandem-x)

population-density/population_file_extraction.py

@@ -8,8 +8,8 @@ Author: Martin Schultz, FZ Juelich (04 May 2016)
 import numpy as np
 import os
 from toar_location_services.settings import DATA_DIR, DEBUG, USE_DUMMY_POPULATION_DATA
+import matplotlib.pyplot as plt
 
-# import matplotlib.pyplot as plt
 
 def read_proxydata(filename, dummy=DEBUG and USE_DUMMY_POPULATION_DATA):
     """Read the ascii file and return the data array together with
@@ -52,11 +52,16 @@ def read_proxydata(filename, dummy=DEBUG and USE_DUMMY_POPULATION_DATA):
             row = np.array([float(x) for x in line.split()], dtype='f4')
             data[i, :] = row
 
+        # correct missing values
+        data[data == float(missval)] = np.nan
+
     logdata = data.copy()
     logdata[logdata <= 1.e-4] = 1.e-4
-    # plt.contourf(lonvec, latvec, np.log10(logdata))
-    # plt.savefig('global_population_density.png')
-    # plt.close()
+
+    if DEBUG:
+        plt.contourf(lonvec, latvec, np.log10(logdata))
+        plt.savefig('../plots/global_population_density.png')
+        plt.close()
 
     # set metadata
     boundingbox = [lon0, lat0, lonvec.max(), latvec.max()]