Sort courses announcement date

If there is no announcement date (in the policy metadata) then use a
heuristic to sort them.

If there is an announcement date, the use it in the heuristic to
determine if the course is new or not.

common/djangoapps/student/views.py

@@ -42,7 +42,7 @@ from xmodule.modulestore.django import modulestore
 #from datetime import date
 from collections import namedtuple
 
-from courseware.courses import get_courses
+from courseware.courses import get_courses, sort_by_announcement
 from courseware.access import has_access
 
 from statsd import statsd
@@ -78,10 +78,7 @@ def index(request, extra_context={}, user=None):
         domain = request.META.get('HTTP_HOST')
 
     courses = get_courses(None, domain=domain)
-
-    # Sort courses by how far are they from they start day
-    key = lambda course: course.days_until_start
-    courses = sorted(courses, key=key, reverse=True)
+    courses = sort_by_announcement(courses)
 
     # Get the 3 most recent news
     top_news = _get_news(top=3)

common/lib/xmodule/xmodule/course_module.py

 import logging
+from math import exp, erf
 from lxml import etree
 from path import path  # NOTE (THK): Only used for detecting presence of syllabus
 import requests
@@ -183,35 +184,66 @@ class CourseDescriptor(SequenceDescriptor):
 
     @property
     def is_new(self):
-        # The course is "new" if either if the metadata flag is_new is
-        # true or if the course has not started yet
+        """
+        Returns if the course has been flagged as new in the metadata. If
+        there is no flag, return a heuristic value considering the
+        announcement and the start dates.
+        """
         flag = self.metadata.get('is_new', None)
         if flag is None:
-            return self.days_until_start > 1
+            # Use a heuristic if the course has not been flagged
+            announcement, start, now = self._sorting_dates()
+            if announcement and (now - announcement).days < 30:
+                # The course has been announced for less that month
+                return True
+            elif (now - start).days < 1:
+                # The course has not started yet
+                return True
+            else:
+                return False
         elif isinstance(flag, basestring):
             return flag.lower() in ['true', 'yes', 'y']
         else:
             return bool(flag)
 
     @property
-    def days_until_start(self):
-        def convert_to_datetime(timestamp):
+    def sorting_score(self):
+        """
+        Returns a number that can be used to sort the courses according
+        the how "new"" they are. The "newness"" score is computed using a
+        heuristic that takes into account the announcement and
+        (advertized) start dates of the course if available.
+
+        The lower the number the "newer" the course.
+        """
+        # Make courses that have an announcement date shave a lower
+        # score than courses than don't, older courses should have a
+        # higher score.
+        announcement, start, now = self._sorting_dates()
+        scale = 300.0  # about a year
+        if announcement:
+            days = (now - announcement).days
+            score = -exp(-days/scale)
+        else:
+            days = (now - start).days
+            score = exp(days/scale)
+        return score
+
+    def _sorting_dates(self):
+        # utility function to get datetime objects for dates used to
+        # compute the is_new flag and the sorting_score
+        def to_datetime(timestamp):
             return datetime.fromtimestamp(time.mktime(timestamp))
 
-        start_date = convert_to_datetime(self.start)
+        def get_date(field):
+            timetuple = self._try_parse_time(field)
+            return to_datetime(timetuple) if timetuple else None
 
-        #  Try to use course advertised date if we can parse it
-        advertised_start = self.metadata.get('advertised_start', None)
-        if advertised_start:
-            try:
-                start_date = datetime.strptime(advertised_start,
-                                               "%Y-%m-%dT%H:%M")
-            except ValueError:
-                pass  # Invalid date, keep using 'start''
-
-        now = convert_to_datetime(time.gmtime())
-        days_until_start = (start_date - now).days
-        return days_until_start
+        announcement = get_date('announcement')
+        start = get_date('advertised_start') or to_datetime(self.start)
+        now = to_datetime(time.gmtime())
+
+        return announcement, start, now
 
     @lazyproperty
     def grading_context(self):

common/lib/xmodule/xmodule/tests/test_course_module.py

 import unittest
-from time import strptime, gmtime
+from time import strptime
 from fs.memoryfs import MemoryFS
 
 from mock import Mock, patch
@@ -39,52 +39,81 @@ class DummySystem(ImportSystem):
 class IsNewCourseTestCase(unittest.TestCase):
     """Make sure the property is_new works on courses"""
     @staticmethod
-    def get_dummy_course(start, is_new=None, load_error_modules=True):
+    def get_dummy_course(start, announcement=None, is_new=None):
         """Get a dummy course"""
 
-        system = DummySystem(load_error_modules)
-        is_new = '' if is_new is None else 'is_new="{0}"'.format(is_new).lower()
+        system = DummySystem(load_error_modules=True)
+
+        def to_attrb(n, v):
+            return '' if v is None else '{0}="{1}"'.format(n, v).lower()
+
+        is_new = to_attrb('is_new', is_new)
+        announcement = to_attrb('announcement', announcement)
 
         start_xml = '''
          <course org="{org}" course="{course}"
                 graceperiod="1 day" url_name="test"
                 start="{start}"
+                {announcement}
                 {is_new}>
             <chapter url="hi" url_name="ch" display_name="CH">
                 <html url_name="h" display_name="H">Two houses, ...</html>
             </chapter>
          </course>
-         '''.format(org=ORG, course=COURSE, start=start, is_new=is_new)
+         '''.format(org=ORG, course=COURSE, start=start, is_new=is_new,
+                    announcement=announcement)
 
         return system.process_xml(start_xml)
 
     @patch('xmodule.course_module.time.gmtime')
-    def test_non_started_yet(self, gmtime_mock):
-        descriptor = self.get_dummy_course(start='2013-01-05T12:00')
-        gmtime_mock.return_value = NOW
-        assert(descriptor.is_new == True)
-        assert(descriptor.days_until_start == 4)
-
-    @patch('xmodule.course_module.time.gmtime')
-    def test_already_started(self, gmtime_mock):
+    def test_sorting_score(self, gmtime_mock):
         gmtime_mock.return_value = NOW
+        dates = [('2012-10-01T12:00', '2012-09-01T12:00'),  # 0
+                 ('2012-12-01T12:00', '2012-11-01T12:00'),  # 1
+                 ('2013-02-01T12:00', '2012-12-01T12:00'),  # 2
+                 ('2013-02-01T12:00', '2012-11-10T12:00'),  # 3
+                 ('2013-02-01T12:00', None),                # 4
+                 ('2013-03-01T12:00', None),                # 5
+                 ('2013-04-01T12:00', None),                # 6
+                 ('2012-11-01T12:00', None),                # 7
+                 ('2012-09-01T12:00', None),                # 8
+                 ('1990-01-01T12:00', None),                # 9
+                 ('2013-01-02T12:00', None),                # 10
+                 ('2013-01-10T12:00', '2012-12-31T12:00'),  # 11
+                 ('2013-01-10T12:00', '2013-01-01T12:00'),  # 12
+        ]
+
+        data = []
+        for i, d in enumerate(dates):
+            descriptor = self.get_dummy_course(start=d[0], announcement=d[1])
+            score = descriptor.sorting_score
+            data.append((score, i))
+
+        result = [d[1] for d in sorted(data)]
+        assert(result == [12, 11, 2, 3, 1, 0, 6, 5, 4, 10, 7, 8, 9])
 
-        descriptor = self.get_dummy_course(start='2012-12-02T12:00')
-        assert(descriptor.is_new == False)
-        assert(descriptor.days_until_start < 0)
 
     @patch('xmodule.course_module.time.gmtime')
-    def test_is_new_set(self, gmtime_mock):
+    def test_is_new(self, gmtime_mock):
         gmtime_mock.return_value = NOW
 
         descriptor = self.get_dummy_course(start='2012-12-02T12:00', is_new=True)
-        assert(descriptor.is_new == True)
-        assert(descriptor.days_until_start < 0)
+        assert(descriptor.is_new is True)
 
         descriptor = self.get_dummy_course(start='2013-02-02T12:00', is_new=False)
-        assert(descriptor.is_new == False)
-        assert(descriptor.days_until_start > 0)
+        assert(descriptor.is_new is False)
 
         descriptor = self.get_dummy_course(start='2013-02-02T12:00', is_new=True)
-        assert(descriptor.is_new == True)
-        assert(descriptor.days_until_start > 0)
+        assert(descriptor.is_new is True)
+
+        descriptor = self.get_dummy_course(start='2013-01-15T12:00')
+        assert(descriptor.is_new is True)
+
+        descriptor = self.get_dummy_course(start='2013-03-00T12:00')
+        assert(descriptor.is_new is True)
+
+        descriptor = self.get_dummy_course(start='2012-10-15T12:00')
+        assert(descriptor.is_new is False)
+
+        descriptor = self.get_dummy_course(start='2012-12-31T12:00')
+        assert(descriptor.is_new is True)

lms/djangoapps/courseware/courses.py

@@ -64,6 +64,7 @@ def course_image_url(course):
     path = course.metadata['data_dir'] + "/images/course_image.jpg"
     return try_staticfiles_lookup(path)
 
+
 def find_file(fs, dirs, filename):
     """
     Looks for a filename in a list of dirs on a filesystem, in the specified order.
@@ -80,6 +81,7 @@ def find_file(fs, dirs, filename):
             return filepath
     raise ResourceNotFoundError("Could not find {0}".format(filename))
 
+
 def get_course_about_section(course, section_key):
     """
     This returns the snippet of html to be rendered on the course about page,
@@ -234,4 +236,18 @@ def get_courses(user, domain=None):
     courses = [c for c in courses if has_access(user, c, 'see_exists')]
 
     courses = sorted(courses, key=lambda course:course.number)
+
+    return courses
+
+
+def sort_by_announcement(courses):
+    """
+    Sorts a list of courses by their announcement date. If the date is
+    not available, sort them by their start date.
+    """
+
+    # Sort courses by how far are they from they start day
+    key = lambda course: course.sorting_score
+    courses = sorted(courses, key=key)
+
     return courses

lms/djangoapps/courseware/views.py

@@ -17,7 +17,8 @@ from django.views.decorators.cache import cache_control
 
 from courseware import grades
 from courseware.access import has_access
-from courseware.courses import (get_courses, get_course_with_access, get_courses_by_university)
+from courseware.courses import (get_courses, get_course_with_access,
+                                get_courses_by_university, sort_by_announcement)
 import courseware.tabs as tabs
 from courseware.models import StudentModuleCache
 from module_render import toc_for_course, get_module, get_instance_module
@@ -67,11 +68,8 @@ def courses(request):
     '''
     Render "find courses" page.  The course selection work is done in courseware.courses.
     '''
-    courses = get_courses(request.user, domain=request.META.get('HTTP_HOST'))
-
-    # Sort courses by how far are they from they start day
-    key = lambda course: course.days_until_start
-    courses = sorted(courses, key=key, reverse=True)
+    courses = get_courses(request.user, request.META.get('HTTP_HOST'))
+    courses = sort_by_announcement(courses)
 
     return render_to_response("courseware/courses.html", {'courses': courses})
 
@@ -438,10 +436,7 @@ def university_profile(request, org_id):
     # Only grab courses for this org...
     courses = get_courses_by_university(request.user,
                                         domain=request.META.get('HTTP_HOST'))[org_id]
-
-    # Sort courses by how far are they from they start day
-    key = lambda course: course.days_until_start
-    courses = sorted(courses, key=key, reverse=True)
+    courses = sort_by_announcement(courses)
 
     context = dict(courses=courses, org_id=org_id)
     template_file = "university_profile/{0}.html".format(org_id).lower()