Changed format of field_cube from int to byte to save memory

tricco/prepare.py

@@ -81,7 +81,7 @@ def __field_icon(path, file, var, threshold, cubulation):
     array_size=array_size+1 # need to add one as cubulation indices start with 1 instead of 0
     
     # map field from triangular grid to field on cubic grid
-    field_cube = np.zeros((array_size, array_size, array_size), dtype = 'int')
+    field_cube = np.zeros((array_size, array_size, array_size), dtype = 'byte')
     for entry in cubulation:
         triangle = entry[0]     # index of triangle
         cube = entry[1]         # cube coordinate
@@ -109,7 +109,7 @@ def __field_icon_lev(path, file, var, threshold, cubulation):
     array_size=array_size+1 # need to add one as cubulation indices start with 1 instead of 0
     
     # map field from triangular grid to field on nlev x cubic grid
-    field_cube = np.zeros((nlev, array_size, array_size, array_size), dtype = 'int')
+    field_cube = np.zeros((nlev, array_size, array_size, array_size), dtype = 'byte')
     for lev in range(nlev):
         for entry in cubulation:
             triangle = entry[0]     # index of triangle