280 lines
13 KiB
Python
280 lines
13 KiB
Python
import abc
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import logging
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from collections import namedtuple
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log = logging.getLogger("mitx.courseware")
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# This is a tuple for holding scores, either from problems or sections.
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# Section either indicates the name of the problem or the name of the section
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Score = namedtuple("Score", "earned possible graded section")
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def aggregate_scores(scores, section_name="summary"):
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"""
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scores: A list of Score objects
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returns: A tuple (all_total, graded_total).
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all_total: A Score representing the total score summed over all input scores
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graded_total: A Score representing the score summed over all graded input scores
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"""
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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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def grader_from_conf(conf):
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"""
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This creates a CourseGrader from a configuration (such as in course_settings.py).
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The conf can simply be an instance of CourseGrader, in which case no work is done.
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More commonly, the conf is a list of dictionaries. A WeightedSubsectionsGrader
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with AssignmentFormatGrader's or SingleSectionGrader's as subsections will be
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generated. Every dictionary should contain the parameters for making either a
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AssignmentFormatGrader or SingleSectionGrader, in addition to a 'weight' key.
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"""
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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 '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, ValueError) as error:
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errorString = "Unable to parse grader configuration:\n " + str(subgraderconf) + "\n Error was:\n " + str(error)
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log.critical(errorString)
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raise ValueError(errorString)
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return WeightedSubsectionsGrader( subgraders )
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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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__metaclass__ = abc.ABCMeta
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@abc.abstractmethod
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def grade(self, grade_sheet):
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raise NotImplementedError
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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, category, 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(category, 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' : category} )
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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 'type' and the name 'name'.
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If the 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, type, name, short_label = None, category = None):
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self.type = type
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self.name = name
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self.short_label = short_label or name
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self.category = category or name
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def grade(self, grade_sheet):
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foundScore = None
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if self.type in grade_sheet:
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for score in grade_sheet[self.type]:
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if score.section == self.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.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.name)
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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 matching the format 'type' 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, type, min_count, drop_count, category = None, section_type = None, short_label = None):
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self.type = type
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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.type
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self.section_type = section_type or self.type
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self.short_label = short_label or self.type
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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.type, [])
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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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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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