Merge pull request #32 from sfinkens/fix-ch3-encoding

Fix channel 3 encoding

Author: sfinkens

pygac_fdr/tests/test_writer.py

@@ -16,8 +16,9 @@
 # You should have received a copy of the GNU General Public License along with
 # pygac-fdr. If not, see <http://www.gnu.org/licenses/>.
 
+import numpy as np
 import unittest
-from pygac_fdr.writer import NetcdfWriter
+from pygac_fdr.writer import NetcdfWriter, DEFAULT_ENCODING
 
 
 class NetcdfWriterTest(unittest.TestCase):
@@ -27,3 +28,22 @@ def test_get_integer_version(self):
         self.assertEqual(writer._get_integer_version('1.2.3'), 123)
         self.assertEqual(writer._get_integer_version('12.3.4'), 1234)
         self.assertRaises(ValueError, writer._get_integer_version, '1.10.1')
+
+    def test_default_encoding(self):
+        bt_range = np.arange(170, 330, 1, dtype='f8')
+        refl_range = np.arange(0, 1.5, 0.1, dtype='f8')
+        test_data = {
+            'reflectance_channel_1': refl_range,
+            'reflectance_channel_2': refl_range,
+            'brightness_temperature_channel_3': bt_range,
+            'reflectance_channel_3a': refl_range,
+            'brightness_temperature_channel_3b': bt_range,
+            'brightness_temperature_channel_4': bt_range,
+            'brightness_temperature_channel_5': bt_range
+        }
+        for ch, data in test_data.items():
+            enc = DEFAULT_ENCODING[ch]
+            data_enc = ((data - enc['add_offset']) / enc['scale_factor']).astype(
+                enc['dtype'])
+            data_dec = data_enc * enc['scale_factor'] + enc['add_offset']
+            np.testing.assert_allclose(data_dec, data, rtol=0.1)

pygac_fdr/writer.py

@@ -65,12 +65,12 @@
                               '_FillValue': FILL_VALUE_INT16,
                               'zlib': True,
                               'complevel': 4},
-    'reflectance_channel_3': {'dtype': 'int16',
-                              'scale_factor': 0.01,
-                              'add_offset': 0,
-                              '_FillValue': FILL_VALUE_INT16,
-                              'zlib': True,
-                              'complevel': 4},
+    'brightness_temperature_channel_3': {'dtype': 'int16',
+                                         'scale_factor': 0.01,
+                                         'add_offset': 273.15,
+                                         '_FillValue': FILL_VALUE_INT16,
+                                         'zlib': True,
+                                         'complevel': 4},
     'reflectance_channel_3a': {'dtype': 'int16',
                                'scale_factor': 0.01,
                                'add_offset': 0,