rankingStudentsGraph.py

#!python3
import itertools as it
import os


def relation(A, B):
 if all([a > b for a, b in zip(A, B)]):
 return ">"
 elif all([a < b for a, b in zip(A, B)]):
 return "<"
 return "#"


def read_file(FILENAME):
 roll_marks = {}
 with open(FILENAME, 'r') as f:
 for line in f.readlines():
 roll, *marks = line.split()
 roll_marks[roll] = [int(mark) for mark in marks]
 return roll_marks


def all_relations(FILENAME):
 roll_marks = read_file(FILENAME)
 rolls = roll_marks.keys()
 rels = set()
 for roll1, roll2 in it.combinations(rolls, 2):
 rel = relation(roll_marks[roll1], roll_marks[roll2])
 if rel == ">":
 rels.add(roll1 + roll2)
 elif rel == "<":
 rels.add(roll2 + roll1)
 return rels


def all_removables(rels):
 def is_removable(first, middle, second):
 return first + middle in rels and middle + second in rels

 firsts = set([rel[0] for rel in rels])
 seconds = set([rel[1] for rel in rels])
 both = firsts & seconds
 return set(first+second for first in firsts for second in seconds if first + second in rels for middle in both if is_removable(first, middle, second))


def generate_graph(FILENAME):
 rels = all_relations(FILENAME)
 minimal = rels ^ all_removables(rels)
 with open("partial_orders.dot", "w") as f:
 print("digraph partial_orders {", file=f)
 for relation in minimal:
 print("\t%s -> %s;" % (relation[0], relation[1]), file=f)
 print("}", file=f)

 os.system("dot -T png -o partial_orders.png partial_orders.dot")


if __name__ == "__main__":
 generate_graph('roll_and_marks.txt')