changes.py

def _remap_date_counts(**kwargs):
    """Remap the query result.

    From: [{'count': 2085, 'month': 11, 'year': 2010},...]
    To: {'<label>': 2085, 'date': '2010-11-01'}
    """
    for label, qs in kwargs.iteritems():
        yield dict((date(x['year'], x['month'], 1), {label: x['count']})
                    for x in qs)


def merge_results(**kwargs):
    res_dict = reduce(_merge_results, _remap_date_counts(**kwargs))
    res_list = [dict(date=k, **v) for k, v in res_dict.items()]
    return sorted(res_list, key=itemgetter('date'), reverse=True)

def _merge_results(x, y):
    """Merge query results arrays into one array.

    From:
        [{"date": "2011-10-01", "votes": 3},...]
        and
        [{"date": "2011-10-01", "helpful": 7},...]
    To:
        [{"date": "2011-10-01", "votes": 3, "helpful": 7},...]
    """
    return dict((s, dict(x.get(s, {}).items() + y.get(s, {}).items()))
                    for s in set(x.keys() + y.keys()))

diff.diff

diff --git a/apps/kpi/api.py b/apps/kpi/api.py
index e91a13a..a9e526a 100644
--- a/apps/kpi/api.py
+++ b/apps/kpi/api.py
@@ -24,6 +24,9 @@ class Struct:
     def __init__(self, **entries):
         self.__dict__.update(entries)
 
+    def __unicode__(self):
+        return unicode(self.__dict__)
+
 
 class SolutionResource(Resource):
     """
@@ -104,15 +107,21 @@ def _start_date():
     return date(year_ago.year, year_ago.month, 1)
 
 
-def _remap_date_counts(qs, label):
+def _remap_date_counts(**kwargs):
     """Remap the query result.
 
     From: [{'count': 2085, 'month': 11, 'year': 2010},...]
     To: {'<label>': 2085, 'date': '2010-11-01'}
     """
-    return dict((date(x['year'], x['month'], 1), {label: x['count']})
-                for x in qs)
+    for label, qs in kwargs.iteritems():
+        yield dict((date(x['year'], x['month'], 1), {label: x['count']})
+                    for x in qs)
+
 
+def merge_results(**kwargs):
+    res_dict = reduce(_merge_results, _remap_date_counts(**kwargs))
+    res_list = [dict(date=k, **v) for k, v in res_dict.items()]
+    return sorted(res_list, key=itemgetter('date'), reverse=True)
 
 def _merge_results(x, y):
     """Merge query results arrays into one array.
@@ -124,8 +133,6 @@ def _merge_results(x, y):
     To:
         [{"date": "2011-10-01", "votes": 3, "helpful": 7},...]
     """
-    res_dict = dict((s, dict(x.get(s, {}).items() + y.get(s, {}).items()))
+    return dict((s, dict(x.get(s, {}).items() + y.get(s, {}).items()))
                     for s in set(x.keys() + y.keys()))
-    res_list = [dict(date=k, **v) for k, v in res_dict.items()]
-    return [Struct(**x) for x in sorted(res_list, key=itemgetter('date'),
-                                        reverse=True)]
+

example

In [11]: qs_has_ff = qs.filter(title__icontains='firefox')
In [12]: merge_results(w=qs_with_solutions, wo=qs_without_solutions, ff=qs_has_ff)
Out[12]: 
[{'date': datetime.date(2011, 10, 1), 'w': 1, 'wo': 5},
 {'date': datetime.date(2011, 8, 1), 'ff': 3756, 'w': 707, 'wo': 8144},
 {'date': datetime.date(2011, 7, 1), 'ff': 5434, 'w': 740, 'wo': 11676},
 {'date': datetime.date(2011, 6, 1), 'ff': 6865, 'w': 735, 'wo': 14568},
 {'date': datetime.date(2011, 5, 1), 'ff': 5763, 'w': 841, 'wo': 12164},
 {'date': datetime.date(2011, 4, 1), 'ff': 4787, 'w': 798, 'wo': 10205},
 {'date': datetime.date(2011, 3, 1), 'ff': 7439, 'w': 903, 'wo': 16329},
 {'date': datetime.date(2011, 2, 1), 'ff': 2655, 'w': 330, 'wo': 6562},
 {'date': datetime.date(2011, 1, 1), 'ff': 2611, 'w': 294, 'wo': 6284},
 {'date': datetime.date(2010, 12, 1), 'ff': 2009, 'w': 232, 'wo': 4858},
 {'date': datetime.date(2010, 11, 1), 'ff': 1837, 'w': 208, 'wo': 4320},
 {'date': datetime.date(2010, 10, 1), 'ff': 2055, 'w': 259, 'wo': 4750},
 {'date': datetime.date(2010, 9, 1), 'ff': 2172, 'w': 307, 'wo': 4808},
 {'date': datetime.date(2010, 8, 1), 'ff': 1745, 'w': 197, 'wo': 3985},
 {'date': datetime.date(2010, 7, 1), 'ff': 2292, 'w': 508, 'wo': 4919},
 {'date': datetime.date(2010, 6, 1), 'ff': 1961, 'w': 540, 'wo': 4130},
 {'date': datetime.date(2010, 5, 1), 'ff': 1763, 'w': 567, 'wo': 3861},
 {'date': datetime.date(2010, 4, 1), 'ff': 19, 'w': 2, 'wo': 32},
 {'date': datetime.date(2010, 3, 1), 'ff': 23, 'wo': 41},
 {'date': datetime.date(2010, 2, 1), 'ff': 20, 'w': 4, 'wo': 41},
 {'date': datetime.date(2010, 1, 1), 'ff': 3, 'w': 1, 'wo': 11},
 {'date': datetime.date(2009, 12, 1), 'ff': 1, 'wo': 1}]