Better error handling

README.md

@@ -290,6 +290,11 @@ Recording solar radiation gets us the most accurate ETo:
 
 # TODO
 
+ * rounding consistency. Currently rounding of decimal points for floating point numbers
+   follow the [original paper][1]'s usage examples. I did so in order to be able
+   to test examples used in the paper. However this is far from ideal. This
+   issue of significant digits must be revisited in future revisions!
+
  * *import_data()* must be supported by *penmon.eto.Station* class to import
    bulk data into the station.
 

setup.py

@@ -3,15 +3,15 @@
 
 setup(
     name="penmon",
-    version="0.2.0",
+    version="0.2.1",
     description="Implementation of Penman-Monteith equation to calculate ET for a reference crop",
     # long_description_content_type="text/markdown",
     # long_description=long_description,
     author="Sherzod RUZMETOV",
     author_email="[email protected]",
     license="MIT",
     url="https://github.com/sherzodr/penmon",
-    download_url="https://github.com/sherzodr/penmon/archive/0.2.0.tar.gz",
+    download_url="https://github.com/sherzodr/penmon/archive/0.2.1.tar.gz",
     py_modules=["penmon.eto"],
     package_dir={'': 'src'},
     packages=["penmon"],
@@ -23,4 +23,3 @@
         "Topic :: Scientific/Engineering :: Atmospheric Science"
         ]
     )
-

src/penmon/eto.py

@@ -15,15 +15,13 @@
 CHECK_RADIATION_RANGE = True
 CHECK_SUNSHINE_HOURS_RANGE = True
 
-
 def is_number(s):
     try:
         float(s)
         return True
     except ValueError:
         return False
 
-
 class Station:
     """ Class that implements a weather station at a known latitude and elevation."""
 
@@ -50,6 +48,12 @@ def __init__(self, latitude, altitude, anemometer_height=2):
          * climate - set to default **Climate()** instance
          * ref_crop - instance of **Crop** class, which sets default chracteristics
                       of the reference crop according to the paper.
+                      
+        Should you wish to change assumes Climate and Crop characteristics
+        you can do so after the object is innitialized, like so:
+        
+            station=Station(41.42, 109)
+            station.ref_crop = Crop(albedo=0.25, height=0.35)
         """
 
         if not type(latitude) is float:
@@ -81,6 +85,7 @@ def day(self, day_number):
     def get_day(self, day_number, date_template="%Y-%m-%d",
                 temp_min=None,
                 temp_max=None,
+                temp_mean=None,
                 wind_speed=None,
                 humidity_mean=None,
                 radiation_s=None,
@@ -135,6 +140,7 @@ def get_day(self, day_number, date_template="%Y-%m-%d",
         self.days[day_number] = day
         day.temp_min = temp_min
         day.temp_max = temp_max
+        day.temp_mean=temp_mean
         day.humidity_mean = humidity_mean
         day.wind_speed = wind_speed
 
@@ -206,7 +212,6 @@ def __init__(self, day_number, station):
         - vapour_pressure
         - wind_speed
         - radiation_s
-        - radiation_a
         - stephan_boltzman_constant
         - climate  - convenient reference to station.climate
         - sunshine_hours
@@ -224,7 +229,6 @@ def __init__(self, day_number, station):
         self.humidity_max = None
         self.wind_speed = None
         self.radiation_s = None
-        self.radiation_a = None
         self.temp_dew = None
         self.temp_dry = None
         self.temp_wet = None
@@ -254,7 +258,7 @@ def wind_speed_2m(self):
         # speed at 2m
         if self.wind_speed and self.station.anemometer_height != 2:
             return round(self.wind_speed * (4.87 /
-                                                       math.log(67.8 * self.station.anemometer_height - 5.42)), 1)
+                                            math.log(67.8 * self.station.anemometer_height - 5.42)), 1)
 
         # if we reach this far no wind information is available to work with. we
         # consult if station has any climatic data, in which case we try to
@@ -551,6 +555,9 @@ def R_nl(self):
         """
         Net longwave radiation. (Eq. 39)
         """
+
+        if not ( self.temp_max and self.temp_min ):
+            raise Exception("Net longwave radiation cannot be calculated without min/max temperature")
 
         TmaxK = self.temp_max + 273.16
         TminK = self.temp_min + 273.16
@@ -560,15 +567,19 @@ def R_nl(self):
 
         sb_constant = self.stephan_boltzmann_constant
         return round(sb_constant * ((TmaxK ** 4 + TminK ** 4) / 2) *
-                     (0.34 - 0.14 * math.sqrt(ea)) * 
+                     (0.34 - 0.14 * math.sqrt(ea)) *
                      (1.35 * (rs / rso) - 0.35), 1)
 
     def net_radiation(self):
         """
         Net Radiation. (Eq. 40)
         """
         ns = self.R_ns()
-        nl = self.R_nl()
+
+        try: 
+            nl = self.R_nl()
+        except Exception as e: 
+            raise(str(e))
 
         if (not ns is None) and (not nl is None):
             return round(ns - nl, 1)
@@ -613,31 +624,32 @@ def eto(self):
         Eq. 6
         """
 
-        Tmax = self.temp_max
-        Tmin = self.temp_min
-
         # if we cannot get wind speed data we revert to Hargreaves formula.
-        # Which is not ideal!
+        # Which is not ideal! This can happen only if user removed default 'climate'
+        # reference
         if not self.wind_speed_2m():
             return self.eto_hargreaves()
 
-        if Tmax and Tmin:
-            Tmean = (Tmax + Tmin) / 2
-
-            slope_of_vp = self.slope_of_saturation_vapour_pressure(Tmean)
-            net_radiation = self.net_radiation()
-            G = self.soil_heat_flux()
-            u2m = self.wind_speed_2m()
 
-            eto_nominator = (0.408 * slope_of_vp * (net_radiation - G) +
-                             self.psychrometric_constant() * (900 / (Tmean + 273)) * u2m *
-                             self.vapour_pressure_deficit())
+        if self.Tmean() == None:
+            raise Exception(
+                "Cannot calculate eto(): temp_mean (mean temperature) is missing")
 
-            eto_denominator = slope_of_vp + self.psychrometric_constant() * (1 + 0.34 * u2m)
-
-            return round(eto_nominator / eto_denominator, 2)
-
-        return None
+        try:
+            net_radiation = self.net_radiation()
+        except Exception as e:
+            raise(str(e))
+
+        Tmean=self.Tmean()
+        slope_of_vp = self.slope_of_saturation_vapour_pressure(Tmean)
+        G = self.soil_heat_flux()
+        u2m = self.wind_speed_2m()
+        eto_nominator = (0.408 * slope_of_vp * (net_radiation - G) +
+                         self.psychrometric_constant() * (900 / (Tmean + 273)) * u2m *
+                         self.vapour_pressure_deficit())
+
+        eto_denominator = slope_of_vp + self.psychrometric_constant() * (1 + 0.34 * u2m)
+        return round(eto_nominator / eto_denominator, 2)
 
 
 class Climate:

tests/error_handling.py

@@ -6,7 +6,6 @@
 import unittest
 import penmon.eto as pm
 
-
 class Test(unittest.TestCase):
 
     def test_smoke(self):
@@ -15,23 +14,23 @@ def test_smoke(self):
 
     def test_type_error(self):
         try:
-            station = pm.Station(latitude=10, altitude=109)
+            pm.Station(latitude=10, altitude=109)
         except TypeError:
             self.assertTrue(True, "Exception was expected and raised")
         else:
             self.assertTrue(False, "Exception was expected but was NOT raised")
 
     def test_latitude_range_error(self):
         try:
-            station = pm.Station(latitude=100.0, altitude=100)
+            pm.Station(latitude=100.0, altitude=100)
         except:
             self.assertTrue(True, "Exception was expected and raised")
         else:
             self.assertTrue(False, "Exception was expected but was NOT raised")
 
     def test_altitude_range_error(self):
         try:
-            station = pm.Station(latitude=41.42, altitude=-1)
+            pm.Station(latitude=41.42, altitude=-1)
         except:
             self.assertTrue(True, "Exception was expected and raised")
         else:
@@ -40,7 +39,7 @@ def test_altitude_range_error(self):
     def test_day_number_type(self):
         station = pm.Station(latitude=41.42, altitude=109)
         try:
-            day = station.get_day(365.0)
+            station.get_day(365.0)
         except TypeError:
             self.assertTrue(True, "Exception was expected and raised")
         else:
@@ -50,21 +49,25 @@ def test_day_number_range(self):
         station = pm.Station(latitude=41.42, altitude=109)
 
         try:
-            day = station.get_day(367)
+            station.get_day(367)
         except:
             self.assertTrue(True, "Exception was expected and raised")
         else:
             self.assertTrue(False, "Exception was expected but was NOT raised")
 
-
     def test_immature_eto(self):
         station = pm.Station(41.42, 109)
-        day = station.get_day(238)
+        day = station.get_day(238, temp_mean=25.00)
+        self.assertTrue(day.temp_mean != None, "temp_mean was set")
+        self.assertEqual(day.temp_mean, day.Tmean())
 
-        eto = day.eto()
-
-        self.assertEqual(eto, None)
-
+        # following code should raise an exception:
+        try:
+            day.eto()
+        except Exception as e:
+            self.assertTrue(True, str(e))
+        else:
+            self.assertTrue(False, "Exception was expected")
 
 if __name__ == "__main__":
     # import sys;sys.argv = ['', 'Test.testName']