#!/usr/bin/env python3

"""https://graphviz.org/Gallery/undirected/ER.html"""

import graphviz

e = graphviz.Graph('ER', filename='er.gv', engine='neato')

e.attr('node', shape='box')
e.node('course')
e.node('institute')
e.node('student')

e.attr('node', shape='ellipse')
e.node('name0', label='name')
e.node('name1', label='name')
e.node('name2', label='name')
e.node('code')
e.node('grade')
e.node('number')

e.attr('node', shape='diamond', style='filled', color='lightgrey')
e.node('C-I')
e.node('S-C')
e.node('S-I')

e.edge('name0', 'course')
e.edge('code', 'course')
e.edge('course', 'C-I', label='n', len='1.00')
e.edge('C-I', 'institute', label='1', len='1.00')
e.edge('institute', 'name1')
e.edge('institute', 'S-I', label='1', len='1.00')
e.edge('S-I', 'student', label='n', len='1.00')
e.edge('student', 'grade')
e.edge('student', 'name2')
e.edge('student', 'number')
e.edge('student', 'S-C', label='m', len='1.00')
e.edge('S-C', 'course', label='n', len='1.00')

e.attr(label=r'\n\nEntity Relation Diagram\ndrawn by NEATO')
e.attr(fontsize='20')

e.view()
