Using dictionary of letter grades, calculate mean GPA from list of letter grades converted to points

gpa-calc.py

#!/usr/bin/env python3
"""Using dictionary of letter grades, calculate mean GPA from list
of letter grades converted to points"""

# https://gist.github.com/reagle/9cc2f4e2f98446528128d1f6edfe3d73
# add results to e-statement-1b-teaching-trace-table.xlsx

__author__ = "Joseph Reagle"
__copyright__ = "Copyright (C) 2021-2024 Joseph Reagle"
__license__ = "GLPv3"
__version__ = "1.1"


import statistics
from collections import Counter

try:
    import asciietch.graph as ag  # type:ignore

    asciietch_imported = True
except ImportError:
    asciietch_imported = False
    print("`pip install asciietch` if you want nice graphs ▁▅█▂▁▃▁▂▁▁▁▂▁")
    print("    https://github.com/linkedin/asciietch\n")

# https://registrar.northeastern.edu/article/how-to-calculate-your-gpa/
POINTS = {
    "A+": 4.0,
    "A": 4.0,
    "A-": 3.667,
    "B+": 3.333,
    "B": 3.0,
    "B-": 2.667,
    "C+": 2.333,
    "C": 2.0,
    "C-": 1.667,
    "D+": 1.333,
    "D": 1.0,
    "D-": 0.667,
    "F": 0,
}


def calc_gpa(grades: list[str]) -> float:
    """Calculate mean GPA from list of letter grades converted to points."""
    return statistics.mean([POINTS[grade] for grade in grades])


def print_header():
    """Print a header for the output."""
    print(f"{'COURSE':<15} {'N':<5} {'MEAN':<10}", end="")
    print(" ".join(f"{letter:<2}" for letter in POINTS.keys()))


def print_course(title: str, grades: list[str]) -> None:
    """Print single-line information for a course."""
    print(f"{title:<15} N={len(grades):02d}  μ={calc_gpa(grades):.2f}", end="    ")
    distribution = [grades.count(letter) for letter in POINTS]
    counter = Counter(grades)
    for letter in POINTS.keys():
        if letter in counter:
            print(f"{counter[letter]:<3}", end="")
        else:
            print("   ", end="")
    if asciietch_imported:
        grapher = ag.Grapher()
        print(grapher.asciihist(distribution), end="")
    print()


COURSES = {  # Target: B+ / 3.33 average
    ################### 2023 Fall
    # 3.35 unprecedented drops at start, leaving mostly strong students
    "2023_CDA_2FA": "A- A A- B- A- A- A- C A A A- A A- D- A B- A- A- B- B+",
    # 3.33 first time teaching public speaking (includes F no show; 3.52 without him)
    "2023_PS_2_FA": "B+ A- B A- A A- B- A B A- B+ A- A- A F B+ A A- B",
    ################### 2023 Spring
    # 3.31
    "2023_CDA_1_SP": (
        "B B A A- A A- A- A- B+ A- A- A- A- A- A- F A B B+ A F A C+ A- A A A- B+ A- C+"
    ),
    # 3.60, excellent students
    "2023_OC_1_SP": "B+ A A B- B+ A- A- A A A- B A A B",
    ################### 2022 Fall
    # 3.44
    "2022_CDA_2FA": (
        "D+ A A B+ A- A- A- A B+ B+ A- A- A A- A- B+ A A B+ B B B+ A- B B B+ A C+"
    ),
    # 3.48
    "2022_OC_2FA": "A- A B+ A C B+ B+ A- A",
    ################### 2022 Spring
    # 3.42
    "2022_CDA_1_SP": (
        "C- A- A A- C- B A- A- A- B+ A B+ B+ A B+ B A- A- A A B+ A A- B A- B+ B"
    ),
    # 3.61, excellent students
    "2022_PC_1_SP": "B+ B+ A A- B+ B+ A B A- A A- A A A- A- A- B",
    # "TEST": "A B B C C C D D D D F F F F F",
}

print_header()
for title, grades in COURSES.items():
    print_course(title, grades.split(" "))