Update calculations to ensure accurate raster totals in HTML report

src/natcap/invest/carbon.py

@@ -673,11 +673,17 @@ def _generate_report(raster_file_set, model_args, file_registry):
 
         for raster_uri, description, units in report:
             if raster_uri in raster_file_set:
-                summary_stat = _accumulate_totals(raster_uri)
+                total = _accumulate_totals(raster_uri)
+                raster_info = pygeoprocessing.get_raster_info(raster_uri)
+                pixel_area = abs(numpy.prod(raster_info['pixel_size']))
+                # Since each pixel value is in Mg/ha, ``total`` is in (Mg/ha * px) = Mg•px/ha.
+                # Adjusted sum = ([total] Mg•px/ha) * ([pixel_area] m^2 / 1 px) * (1 ha / 10000 m^2) = Mg.
+                summary_stat = total * pixel_area / 10000
                 report_doc.write(
-                    '<tr><td>%s</td><td class="number">%.2f</td><td>%s</td>'
-                    '<td>%s</td></tr>' % (
-                        description, summary_stat, units, raster_uri))
+                    '<tr><td>%s</td><td class="number" data-summary-stat="%s">'
+                    '%.2f</td><td>%s</td><td>%s</td></tr>' % (
+                        description, description, summary_stat, units,
+                        raster_uri))
         report_doc.write('</body></html>')
 
 

tests/test_carbon.py

@@ -4,6 +4,7 @@ import unittest
 import tempfile
 import shutil
 import os
+import re
 
 from osgeo import gdal
 from osgeo import osr
@@ -91,6 +92,28 @@ def make_pools_csv(pools_csv_path):
         open_table.write('2,1,5,0,3,"lulc code 3"\n')
 
 
+def assert_aggregate_result_equal(html_report_path, stat_name, val_to_compare):
+    """Assert that the given stat in the HTML report has a specific value.
+
+    Args:
+        html_report_path (str): path to the HTML report generated by the model.
+        stat_name (str): name of the stat to find. Must match the name listed
+            in the HTML.
+        val_to_compare (float): the value to check against.
+
+    Returns:
+        None.
+    """
+    with open(html_report_path) as file:
+        report = file.read()
+        pattern = (r'data-summary-stat="'
+                   + stat_name
+                   + r'">(\-?\d+\.\d{2})</td>')
+        match = re.search(pattern, report)
+        stat_str = match.groups()[0]
+        assert float(stat_str) == val_to_compare
+
+
 class CarbonTests(unittest.TestCase):
     """Tests for the Carbon Model."""
 
@@ -132,14 +155,14 @@ class CarbonTests(unittest.TestCase):
 
         carbon.execute(args)
 
-        # Ensure totals are correct.
-        # Current: 15 + 10 + 60 + 1 = 86 Mg
+        # Ensure every pixel has the correct total C value.
+        # Current: 15 + 10 + 60 + 1 = 86 Mg/ha
         assert_raster_equal_value(
             os.path.join(args['workspace_dir'], 'tot_c_cur.tif'), 86)
-        # Future: 5 + 3 + 20 + 0 = 28 Mg
+        # Future: 5 + 3 + 20 + 0 = 28 Mg/ha
         assert_raster_equal_value(
             os.path.join(args['workspace_dir'], 'tot_c_fut.tif'), 28)
-        # REDD: 2 + 1 + 5 + 0 = 8 Mg
+        # REDD: 2 + 1 + 5 + 0 = 8 Mg/ha
         assert_raster_equal_value(
             os.path.join(args['workspace_dir'], 'tot_c_redd.tif'), 8)
 
@@ -158,6 +181,21 @@ class CarbonTests(unittest.TestCase):
         assert_raster_equal_value(
             os.path.join(args['workspace_dir'], 'npv_redd.tif'), -4602.106)
 
+        # Ensure aggregate results are correct.
+        report_path = os.path.join(args['workspace_dir'], 'report.html')
+        # Raster size is 100 m^2; therefore, raster total is as follows:
+        # (x Mg / 1 ha) * (1 ha / 10000 m^2) * (100 m^2) = (x / 100) Mg
+        for (stat, expected_value) in [
+                ('Total cur', 0.86),
+                ('Total fut', 0.28),
+                ('Total redd', 0.08),
+                ('Change in C for fut', -0.58),
+                ('Change in C for redd', -0.78),
+                ('Net present value from cur to fut', -34.22),
+                ('Net present value from cur to redd', -46.02),
+                ]:
+            assert_aggregate_result_equal(report_path, stat, expected_value)
+
     def test_carbon_zero_rates(self):
         """Carbon: test with 0 discount and rate change."""
         from natcap.invest import carbon