408 lines
19 KiB
Python
408 lines
19 KiB
Python
import courseware.content_parser as content_parser
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import courseware.modules
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import logging
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import random
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import urllib
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from collections import namedtuple
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from courseware import course_settings
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from django.conf import settings
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from lxml import etree
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from models import StudentModule
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from student.models import UserProfile
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log = logging.getLogger("mitx.courseware")
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Score = namedtuple("Score", "earned possible graded section")
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SectionPercentage = namedtuple("SectionPercentage", "percentage label summary")
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class CourseGrader(object):
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"""
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A course grader takes the totaled scores for each graded section (that a student has
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started) in the course. From these scores, the grader calculates an overall percentage
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grade. The grader should also generate information about how that score was calculated,
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to be displayed in graphs or charts.
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A grader has one required method, grade(), which is passed a grade_sheet. The grade_sheet
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contains scores for all graded section that the student has started. If a student has
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a score of 0 for that section, it may be missing from the grade_sheet. The grade_sheet
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is keyed by section format. Each value is a list of Score namedtuples for each section
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that has the matching section format.
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The grader outputs a dictionary with the following keys:
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- percent: Contaisn a float value, which is the final percentage score for the student.
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- section_breakdown: This is a list of dictionaries which provide details on sections
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that were graded. These are used for display in a graph or chart. The format for a
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section_breakdown dictionary is explained below.
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- grade_breakdown: This is a list of dictionaries which provide details on the contributions
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of the final percentage grade. This is a higher level breakdown, for when the grade is constructed
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of a few very large sections (such as Homeworks, Labs, a Midterm, and a Final). The format for
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a grade_breakdown is explained below. This section is optional.
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A dictionary in the section_breakdown list has the following keys:
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percent: A float percentage for the section.
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label: A short string identifying the section. Preferably fixed-length. E.g. "HW 3".
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detail: A string explanation of the score. E.g. "Homework 1 - Ohms Law - 83% (5/6)"
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category: A string identifying the category. Items with the same category are grouped together
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in the display (for example, by color).
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prominent: A boolean value indicating that this section should be displayed as more prominent
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than other items.
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A dictionary in the grade_breakdown list has the following keys:
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percent: A float percentage in the breakdown. All percents should add up to the final percentage.
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detail: A string explanation of this breakdown. E.g. "Homework - 10% of a possible 15%"
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category: A string identifying the category. Items with the same category are grouped together
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in the display (for example, by color).
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"""
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def grade(self, grade_sheet):
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raise NotImplementedError
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@classmethod
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def graderFromConf(cls, conf):
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if isinstance(conf, CourseGrader):
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return conf
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subgraders = []
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for subgraderconf in conf:
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subgraderconf = subgraderconf.copy()
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weight = subgraderconf.pop("weight", 0)
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try:
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if 'min_count' in subgraderconf:
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#This is an AssignmentFormatGrader
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subgrader = AssignmentFormatGrader(**subgraderconf)
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subgraders.append( (subgrader, subgrader.category, weight) )
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elif 'section_name' in subgraderconf:
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#This is an SingleSectionGrader
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subgrader = SingleSectionGrader(**subgraderconf)
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subgraders.append( (subgrader, subgrader.category, weight) )
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else:
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raise ValueError("Configuration has no appropriate grader class.")
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except TypeError as error:
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log.error("Unable to parse grader configuration:\n" + subgraderconf + "\nError was:\n" + error)
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except ValueError as error:
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log.error("Unable to parse grader configuration:\n" + subgraderconf + "\nError was:\n" + error)
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return WeightedSubsectionsGrader( subgraders )
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class WeightedSubsectionsGrader(CourseGrader):
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"""
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This grader takes a list of tuples containing (grader, category_name, weight) and computes
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a final grade by totalling the contribution of each sub grader and multiplying it by the
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given weight. For example, the sections may be
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[ (homeworkGrader, "Homework", 0.15), (labGrader, "Labs", 0.15), (midtermGrader, "Midterm", 0.30), (finalGrader, "Final", 0.40) ]
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All items in section_breakdown for each subgrader will be combined. A grade_breakdown will be
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composed using the score from each grader.
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Note that the sum of the weights is not take into consideration. If the weights add up to
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a value > 1, the student may end up with a percent > 100%. This allows for sections that
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are extra credit.
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"""
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def __init__(self, sections):
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self.sections = sections
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def grade(self, grade_sheet):
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total_percent = 0.0
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section_breakdown = []
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grade_breakdown = []
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for subgrader, section_name, weight in self.sections:
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subgrade_result = subgrader.grade(grade_sheet)
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weightedPercent = subgrade_result['percent'] * weight
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section_detail = "{0} = {1:.1%} of a possible {2:.0%}".format(section_name, weightedPercent, weight)
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total_percent += weightedPercent
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section_breakdown += subgrade_result['section_breakdown']
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grade_breakdown.append( {'percent' : weightedPercent, 'detail' : section_detail, 'category' : section_name} )
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return {'percent' : total_percent,
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'section_breakdown' : section_breakdown,
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'grade_breakdown' : grade_breakdown}
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class SingleSectionGrader(CourseGrader):
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"""
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This grades a single section with the format section_format and the name section_name.
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If the section_name is not appropriate for the short short_label or category, they each may
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be specified individually.
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"""
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def __init__(self, section_format, section_name, short_label = None, category = None):
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self.section_format = section_format
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self.section_name = section_name
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self.short_label = short_label or section_name
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self.category = category or section_name
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def grade(self, grade_sheet):
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foundScore = None
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if self.section_format in grade_sheet:
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for score in grade_sheet[self.section_format]:
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if score.section == self.section_name:
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foundScore = score
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break
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if foundScore:
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percent = foundScore.earned / float(foundScore.possible)
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detail = "{name} - {percent:.0%} ({earned:.3n}/{possible:.3n})".format( name = self.section_name,
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percent = percent,
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earned = float(foundScore.earned),
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possible = float(foundScore.possible))
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else:
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percent = 0.0
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detail = "{name} - 0% (?/?)".format(name = self.section_name)
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if settings.GENERATE_PROFILE_SCORES:
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points_possible = random.randrange(50, 100)
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points_earned = random.randrange(40, points_possible)
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percent = points_earned / float(points_possible)
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detail = "{name} - {percent:.0%} ({earned:.3n}/{possible:.3n})".format( name = self.section_name,
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percent = percent,
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earned = float(points_earned),
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possible = float(points_possible))
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breakdown = [{'percent': percent, 'label': self.short_label, 'detail': detail, 'category': self.category, 'prominent': True}]
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return {'percent' : percent,
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'section_breakdown' : breakdown,
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#No grade_breakdown here
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}
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class AssignmentFormatGrader(CourseGrader):
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"""
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Grades all sections specified in course_format with an equal weight. A specified
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number of lowest scores can be dropped from the calculation. The minimum number of
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sections in this format must be specified (even if those sections haven't been
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written yet).
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min_count defines how many assignments are expected throughout the course. Placeholder
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scores (of 0) will be inserted if the number of matching sections in the course is < min_count.
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If there number of matching sections in the course is > min_count, min_count will be ignored.
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category should be presentable to the user, but may not appear. When the grade breakdown is
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displayed, scores from the same category will be similar (for example, by color).
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section_type is a string that is the type of a singular section. For example, for Labs it
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would be "Lab". This defaults to be the same as category.
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short_label is similar to section_type, but shorter. For example, for Homework it would be
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"HW".
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"""
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def __init__(self, course_format, min_count, drop_count, category = None, section_type = None, short_label = None):
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self.course_format = course_format
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self.min_count = min_count
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self.drop_count = drop_count
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self.category = category or self.course_format
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self.section_type = section_type or self.course_format
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self.short_label = short_label or self.course_format
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def grade(self, grade_sheet):
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def totalWithDrops(breakdown, drop_count):
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#create an array of tuples with (index, mark), sorted by mark['percent'] descending
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sorted_breakdown = sorted( enumerate(breakdown), key=lambda x: -x[1]['percent'] )
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# A list of the indices of the dropped scores
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dropped_indices = []
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if drop_count > 0:
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dropped_indices = [x[0] for x in sorted_breakdown[-drop_count:]]
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aggregate_score = 0
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for index, mark in enumerate(breakdown):
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if index not in dropped_indices:
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aggregate_score += mark['percent']
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if (len(breakdown) - drop_count > 0):
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aggregate_score /= len(breakdown) - drop_count
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return aggregate_score, dropped_indices
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#Figure the homework scores
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scores = grade_sheet.get(self.course_format, [])
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breakdown = []
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for i in range( max(self.min_count, len(scores)) ):
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if i < len(scores):
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percentage = scores[i].earned / float(scores[i].possible)
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summary = "{section_type} {index} - {name} - {percent:.0%} ({earned:.3n}/{possible:.3n})".format(index = i+1,
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section_type = self.section_type,
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name = scores[i].section,
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percent = percentage,
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earned = float(scores[i].earned),
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possible = float(scores[i].possible) )
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else:
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percentage = 0
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summary = "{section_type} {index} Unreleased - 0% (?/?)".format(index = i+1, section_type = self.section_type)
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if settings.GENERATE_PROFILE_SCORES:
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points_possible = random.randrange(10, 50)
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points_earned = random.randrange(5, points_possible)
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percentage = points_earned / float(points_possible)
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summary = "{section_type} {index} - {name} - {percent:.0%} ({earned:.3n}/{possible:.3n})".format(index = i+1,
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section_type = self.section_type,
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name = "Randomly Generated",
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percent = percentage,
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earned = float(points_earned),
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possible = float(points_possible) )
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short_label = "{short_label} {index:02d}".format(index = i+1, short_label = self.short_label)
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breakdown.append( {'percent': percentage, 'label': short_label, 'detail': summary, 'category': self.category} )
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total_percent, dropped_indices = totalWithDrops(breakdown, self.drop_count)
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for dropped_index in dropped_indices:
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breakdown[dropped_index]['mark'] = {'detail': "The lowest {drop_count} {section_type} scores are dropped.".format(drop_count = self.drop_count, section_type=self.section_type) }
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total_detail = "{section_type} Average = {percent:.0%}".format(percent = total_percent, section_type = self.section_type)
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total_label = "{short_label} Avg".format(short_label = self.short_label)
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breakdown.append( {'percent': total_percent, 'label': total_label, 'detail': total_detail, 'category': self.category, 'prominent': True} )
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return {'percent' : total_percent,
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'section_breakdown' : breakdown,
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#No grade_breakdown here
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}
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def get_score(user, problem, cache):
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## HACK: assumes max score is fixed per problem
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id = problem.get('id')
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correct = 0.0
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# If the ID is not in the cache, add the item
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if id not in cache:
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module = StudentModule(module_type = 'problem', # TODO: Move into StudentModule.__init__?
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module_id = id,
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student = user,
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state = None,
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grade = 0,
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max_grade = None,
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done = 'i')
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cache[id] = module
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# Grab the # correct from cache
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if id in cache:
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response = cache[id]
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if response.grade!=None:
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correct=float(response.grade)
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# Grab max grade from cache, or if it doesn't exist, compute and save to DB
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if id in cache and response.max_grade != None:
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total = response.max_grade
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else:
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total=float(courseware.modules.capa_module.Module(etree.tostring(problem), "id").max_score())
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response.max_grade = total
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response.save()
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#Now we re-weight the problem, if specified
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weight = problem.get("weight", None)
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if weight:
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weight = float(weight)
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correct = correct * weight / total
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total = weight
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return (correct, total)
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def grade_sheet(student):
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"""
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This pulls a summary of all problems in the course. It returns a dictionary with two datastructures:
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- courseware_summary is a summary of all sections with problems in the course. It is organized as an array of chapters,
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each containing an array of sections, each containing an array of scores. This contains information for graded and ungraded
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problems, and is good for displaying a course summary with due dates, etc.
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- grade_summary is the output from the course grader. More information on the format is in the docstring for CourseGrader.
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"""
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dom=content_parser.course_file(student)
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course = dom.xpath('//course/@name')[0]
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xmlChapters = dom.xpath('//course[@name=$course]/chapter', course=course)
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responses=StudentModule.objects.filter(student=student)
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response_by_id = {}
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for response in responses:
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response_by_id[response.module_id] = response
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totaled_scores = {}
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chapters=[]
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for c in xmlChapters:
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sections = []
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chname=c.get('name')
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for s in dom.xpath('//course[@name=$course]/chapter[@name=$chname]/section',
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course=course, chname=chname):
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problems=dom.xpath('//course[@name=$course]/chapter[@name=$chname]/section[@name=$section]//problem',
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course=course, chname=chname, section=s.get('name'))
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graded = True if s.get('graded') == "true" else False
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scores=[]
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if len(problems)>0:
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for p in problems:
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(correct,total) = get_score(student, p, response_by_id)
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if settings.GENERATE_PROFILE_SCORES:
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if total > 1:
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correct = random.randrange( max(total-2, 1) , total + 1 )
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else:
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correct = total
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scores.append( Score(correct,total, graded, p.get("name")) )
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section_total, graded_total = aggregate_scores(scores, s.get("name"))
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#Add the graded total to totaled_scores
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format = s.get('format', "")
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subtitle = s.get('subtitle', format)
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if format and graded_total[1] > 0:
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format_scores = totaled_scores.get(format, [])
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format_scores.append( graded_total )
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totaled_scores[ format ] = format_scores
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section_score={'section':s.get("name"),
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'scores':scores,
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'section_total' : section_total,
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'format' : format,
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'subtitle' : subtitle,
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'due' : s.get("due") or "",
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'graded' : graded,
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}
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sections.append(section_score)
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chapters.append({'course':course,
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'chapter' : c.get("name"),
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'sections' : sections,})
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grader = CourseGrader.graderFromConf(course_settings.GRADER)
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#TODO: We should cache this grader object
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grade_summary = grader.grade(totaled_scores)
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return {'courseware_summary' : chapters,
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'grade_summary' : grade_summary}
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def aggregate_scores(scores, section_name = "summary"):
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total_correct_graded = sum(score.earned for score in scores if score.graded)
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total_possible_graded = sum(score.possible for score in scores if score.graded)
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total_correct = sum(score.earned for score in scores)
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total_possible = sum(score.possible for score in scores)
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#regardless of whether or not it is graded
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all_total = Score(total_correct,
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total_possible,
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False,
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section_name)
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#selecting only graded things
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graded_total = Score(total_correct_graded,
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total_possible_graded,
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True,
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section_name)
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return all_total, graded_total
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