Small refactor on the grades. Also made the gradebook render a graph for each student

--HG--
branch : bridger-grades

courseware/grades.py

+import courseware.content_parser as content_parser
+import courseware.modules
 import logging
+import random
 import urllib
-from lxml import etree
 
-import courseware.content_parser as content_parser
-from models import StudentModule
 from django.conf import settings
-import courseware.modules
-
+from lxml import etree
+from models import StudentModule
 from student.models import UserProfile
 
 log = logging.getLogger("mitx.courseware")
@@ -17,7 +17,7 @@ def get_grade(user, problem, cache):
     correct = 0
     
     # If the ID is not in the cache, add the item
-    if id not in cache: 
+    if id not in cache:
         module = StudentModule(module_type = 'problem',  # TODO: Move into StudentModule.__init__?
                                module_id = id,
                                student = user, 
@@ -44,6 +44,17 @@ def get_grade(user, problem, cache):
     return (correct, total)
 
 def grade_sheet(student):
+    """
+    This pulls a summary of all problems in the course. It returns a dictionary with two datastructures:
+    
+    - courseware_summary is a summary of all sections with problems in the course. It is organized as an array of chapters,
+    each containing an array of sections, each containing an array of scores. This contains information for graded and ungraded
+    problems, and is good for displaying a course summary with due dates, etc.
+    
+    - grade_summary is a summary of how the final grade breaks down. It is an array of "sections". Each section can either be
+    a conglomerate of scores (like labs or homeworks) which has subscores and a totalscore, or a section can be all from one assignment
+    (such as a midterm or final) and only has a totalscore. Each section has a weight that shows how it contributes to the total grade.
+    """
     dom=content_parser.course_file(student)
     course = dom.xpath('//course/@name')[0]
     xmlChapters = dom.xpath('//course[@name=$course]/chapter', course=course)
@@ -54,7 +65,7 @@ def grade_sheet(student):
         response_by_id[response.module_id] = response
     
     
-    total_scores = {}
+    totaled_scores = {}
     chapters=[]
     for c in xmlChapters:
         sections = []
@@ -93,13 +104,13 @@ def grade_sheet(student):
                 graded_total = (sum([score[0] for score in scores if score[2]]), 
                                 sum([score[1] for score in scores if score[2]]))
 
-                #Add the graded total to total_scores
+                #Add the graded total to totaled_scores
                 format = s.get('format') if s.get('format') else ""
                 subtitle = s.get('subtitle') if s.get('subtitle') else format
                 if format and graded_total[1] > 0:
-                    format_scores = total_scores[ format ] if format in total_scores else []
+                    format_scores = totaled_scores[ format ] if format in totaled_scores else []
                     format_scores.append( graded_total + (s.get("name"),) )
-                    total_scores[ format ] = format_scores
+                    totaled_scores[ format ] = format_scores
 
                 score={'section':s.get("name"),
                        'scores':scores,
@@ -114,7 +125,20 @@ def grade_sheet(student):
         chapters.append({'course':course,
                          'chapter' : c.get("name"),
                          'sections' : sections,})
-                         
+    
+    
+    grade_summary = grade_summary_6002x(totaled_scores)
+    
+    return {'courseware_summary' : chapters,
+            'grade_summary' : grade_summary}
+
+
+def grade_summary_6002x(totaled_scores):
+    """
+    This function takes the a dictionary of (graded) section scores, and applies the course grading rules to create
+    the grade_summary. For 6.002x this means homeworks and labs all have equal weight, with the lowest 2 of each
+    being dropped. There is one midterm and one final.
+    """
     
     def totalWithDrops(scores, drop_count):
         #Note that this key will sort the list descending
@@ -131,7 +155,7 @@ def grade_sheet(student):
         return aggregate_score, dropped_indices
         
     #Figure the homework scores
-    homework_scores = total_scores['Homework'] if 'Homework' in total_scores else []
+    homework_scores = totaled_scores['Homework'] if 'Homework' in totaled_scores else []
     homework_percentages = []
     for i in range(12):
         if i < len(homework_scores):
@@ -153,7 +177,7 @@ def grade_sheet(student):
     homework_total, homework_dropped_indices = totalWithDrops(homework_percentages, 2)
     
     #Figure the lab scores
-    lab_scores = total_scores['Lab'] if 'Lab' in total_scores else []
+    lab_scores = totaled_scores['Lab'] if 'Lab' in totaled_scores else []
     lab_percentages = []
     log.debug("lab_scores: {0}".format(lab_scores))
     for i in range(12):
@@ -196,7 +220,8 @@ def grade_sheet(student):
             'category': 'Homework',
             'subscores' : homework_percentages,
             'dropped_indices' : homework_dropped_indices,
-            'totalscore' : {'score' : homework_total, 'summary' : "Homework Average - {0:.0%}".format(homework_total)},
+            'totalscore' : homework_total,
+            'totalscore_summary' : "Homework Average - {0:.0%}".format(homework_total),
             'totallabel' : 'HW Avg',
             'weight' : 0.15,
         },
@@ -204,25 +229,25 @@ def grade_sheet(student):
             'category': 'Labs',
             'subscores' : lab_percentages,
             'dropped_indices' : lab_dropped_indices,
-            'totalscore' : {'score' : lab_total, 'summary' : "Lab Average - {0:.0%}".format(lab_total)},
+            'totalscore' : lab_total,
+            'totalscore_summary' : "Lab Average - {0:.0%}".format(lab_total),
             'totallabel' : 'Lab Avg',
             'weight' : 0.15,
         },
         {
             'category': 'Midterm',
-            'totalscore' : {'score' : midterm_percentage, 'summary' : "Midterm - {0:.0%} ({1}/{2})".format(midterm_percentage, midterm_score[0], midterm_score[1])},
+            'totalscore' : midterm_percentage,
+            'totalscore_summary' : "Midterm - {0:.0%} ({1}/{2})".format(midterm_percentage, midterm_score[0], midterm_score[1]),
             'totallabel' : 'Midterm',
             'weight' : 0.30,
         },
         {
             'category': 'Final',
-            'totalscore' : {'score' : final_percentage, 'summary' : "Final - {0:.0%} ({1}/{2})".format(final_percentage, final_score[0], final_score[1])},
+            'totalscore' : final_percentage,
+            'totalscore_summary' : "Final - {0:.0%} ({1}/{2})".format(final_percentage, final_score[0], final_score[1]),
             'totallabel' : 'Final',
             'weight' : 0.40,
         }
     ]
     
-    return {'grade_summary' : grade_summary,
-            'chapters':chapters}
-
-    
+    return grade_summary