Handle statvar api no data. (#164)

Author: tjann

datacommons/examples/stat_vars.py

@@ -126,6 +126,13 @@ def call_str(pvs):
         dc.get_stat_all(["badPlaceId", "country/FRA"],
                         ["Median_Age_Person", "Count_Person"]))
 
+
+    print('\nWhen no data for get_stat_value')
+    pp.pprint(dc.get_stat_value('foooo', 'barrrr'))
+
+    print('\nWhen no data for get_stat_series')
+    pp.pprint(dc.get_stat_series('foobarbar', 'barfoo'))
+
     print('\nSTRESS TEST FOR GET_STAT_ALL')
     try:
         dc.get_stat_all(

datacommons/stat_vars.py

@@ -51,7 +51,7 @@ def get_stat_value(place,
       scaling_factor (`int`): Optional, the preferred `scalingFactor` value.
     Returns:
       A `float` the value of `stat_var` for `place`, filtered
-      by optional args.
+      by optional args. If no data, returns nan.
 
     Raises:
       ValueError: If the payload returned by the Data Commons REST API is
@@ -77,7 +77,9 @@ def get_stat_value(place,
     try:
         res_json = utils._send_request(url, post=False, use_payload=False)
     except ValueError:
-        raise ValueError('No data in response.')
+        return float('nan')
+    if 'value' not in res_json:
+        return float('nan')
     return res_json['value']
 
 
@@ -120,11 +122,14 @@ def get_stat_series(place,
         url += '&unit={}'.format(unit)
     if scaling_factor:
         url += '&scaling_factor={}'.format(scaling_factor)
-
-    res_json = utils._send_request(url, post=False, use_payload=False)
+    
+    try:
+        res_json = utils._send_request(url, post=False, use_payload=False)
+    except ValueError:
+        return {}
 
     if 'series' not in res_json:
-        raise ValueError('No data in response.')
+        return {}
     return res_json['series']
 
 

datacommons/test/stat_vars_test.py

@@ -27,6 +27,7 @@
 
 import datacommons as dc
 import datacommons.utils as utils
+import math
 import json
 import unittest
 import six
@@ -273,6 +274,9 @@ def test_opt_args(self, urlopen):
                                  'CensusPEPSurvey', 'P1Y', 'RealPeople', 100)
         self.assertEqual(stat, 103)
 
+        # Call get_stat_series with bogus required args
+        stat = dc.get_stat_value('foofoo', 'barrbar')
+        self.assertTrue(math.isnan(stat))
 
 class TestGetStatSeries(unittest.TestCase):
     """Unit tests for get_stat_series."""
@@ -293,6 +297,10 @@ def test_opt_args(self, urlopen):
                                    'CensusPEPSurvey', 'P1Y', 'RealPeople', 100)
         self.assertEqual(stats, {"2000": 3, "2001": 42})
 
+        # Call get_stat_series with bogus required args
+        stats = dc.get_stat_series('foofoofoo', 'barfoobar')
+        self.assertEqual(stats, {})
+
         # Call get_stat_series with non-satisfiable optional args
         stats = dc.get_stat_series('geoId/06', 'Count_Person', 'DNE')
         self.assertEqual(stats, {})