Chess Masters¶
An example of the MultiDiGraph clas
The function chess_pgn_graph reads a collection of chess matches stored in the specified PGN file (PGN =”Portable Game Notation”). Here the (compressed) default file:
chess_masters_WCC.pgn.bz2
contains all 685 World Chess Championship matches from 1886–1985. (data from http://chessproblem.my-free-games.com/chess/games/Download-PGN.php)
The chess_pgn_graph() function returns a MultiDiGraph with multiple edges.
Each node is the last name of a chess master. Each edge is directed from white
to black and contains selected game info.
The key statement in chess_pgn_graph below is:
G.add_edge(white, black, game_info)
where game_info is a dict describing each game.
Out:
Loaded 685 chess games between 25 players
Note the disconnected component consisting of:
[u'Karpov, Anatoly', u'Korchnoi, Viktor L', u'Kasparov, Gary']
From a total of 237 different openings,
the following games used the Sicilian opening
with the Najdorff 7...Qb6 "Poisoned Pawn" variation.
(u'Spassky, Boris V', 'vs', u'Fischer, Robert J')
(' ', 'ECO', ': ', u'B97')
(' ', 'WhiteElo', ': ', u'2660')
(' ', 'Site', ': ', u'Reykjavik ISL')
(' ', 'BlackElo', ': ', u'2785')
(' ', 'EventDate', ': ', u'1972.07.11')
(' ', 'Result', ': ', u'1/2-1/2')
(' ', 'Date', ': ', u'1972.07.25')
(' ', 'Round', ': ', u'7')
(' ', 'Event', ': ', u'World Championship 28th')
(u'Spassky, Boris V', 'vs', u'Fischer, Robert J')
(' ', 'ECO', ': ', u'B97')
(' ', 'WhiteElo', ': ', u'2660')
(' ', 'Site', ': ', u'Reykjavik ISL')
(' ', 'BlackElo', ': ', u'2785')
(' ', 'EventDate', ': ', u'1972.07.11')
(' ', 'Result', ': ', u'1-0')
(' ', 'Date', ': ', u'1972.08.06')
(' ', 'Round', ': ', u'11')
(' ', 'Event', ': ', u'World Championship 28th')
# Copyright (C) 2006-2018 by
# Aric Hagberg <hagberg@lanl.gov>
# Dan Schult <dschult@colgate.edu>
# Pieter Swart <swart@lanl.gov>
# All rights reserved.
# BSD license.
import matplotlib.pyplot as plt
import networkx as nx
# tag names specifying what game info should be
# stored in the dict on each digraph edge
game_details = ["Event",
"Date",
"Result",
"ECO",
"Site"]
def chess_pgn_graph(pgn_file="chess_masters_WCC.pgn.bz2"):
"""Read chess games in pgn format in pgn_file.
Filenames ending in .gz or .bz2 will be uncompressed.
Return the MultiDiGraph of players connected by a chess game.
Edges contain game data in a dict.
"""
import bz2
G = nx.MultiDiGraph()
game = {}
datafile = bz2.BZ2File(pgn_file)
lines = (line.decode().rstrip('\r\n') for line in datafile)
for line in lines:
if line.startswith('['):
tag, value = line[1:-1].split(' ', 1)
game[str(tag)] = value.strip('"')
else:
# empty line after tag set indicates
# we finished reading game info
if game:
white = game.pop('White')
black = game.pop('Black')
G.add_edge(white, black, **game)
game = {}
return G
if __name__ == '__main__':
G = chess_pgn_graph()
ngames = G.number_of_edges()
nplayers = G.number_of_nodes()
print("Loaded %d chess games between %d players\n"
% (ngames, nplayers))
# identify connected components
# of the undirected version
Gcc = list(nx.connected_component_subgraphs(G.to_undirected()))
if len(Gcc) > 1:
print("Note the disconnected component consisting of:")
print(Gcc[1].nodes())
# find all games with B97 opening (as described in ECO)
openings = set([game_info['ECO']
for (white, black, game_info) in G.edges(data=True)])
print("\nFrom a total of %d different openings," % len(openings))
print('the following games used the Sicilian opening')
print('with the Najdorff 7...Qb6 "Poisoned Pawn" variation.\n')
for (white, black, game_info) in G.edges(data=True):
if game_info['ECO'] == 'B97':
print(white, "vs", black)
for k, v in game_info.items():
print(" ", k, ": ", v)
print("\n")
# make new undirected graph H without multi-edges
H = nx.Graph(G)
# edge width is proportional number of games played
edgewidth = []
for (u, v, d) in H.edges(data=True):
edgewidth.append(len(G.get_edge_data(u, v)))
# node size is proportional to number of games won
wins = dict.fromkeys(G.nodes(), 0.0)
for (u, v, d) in G.edges(data=True):
r = d['Result'].split('-')
if r[0] == '1':
wins[u] += 1.0
elif r[0] == '1/2':
wins[u] += 0.5
wins[v] += 0.5
else:
wins[v] += 1.0
try:
pos = nx.nx_agraph.graphviz_layout(H)
except:
pos = nx.spring_layout(H, iterations=20)
plt.rcParams['text.usetex'] = False
plt.figure(figsize=(8, 8))
nx.draw_networkx_edges(H, pos, alpha=0.3, width=edgewidth, edge_color='m')
nodesize = [wins[v] * 50 for v in H]
nx.draw_networkx_nodes(H, pos, node_size=nodesize, node_color='w', alpha=0.4)
nx.draw_networkx_edges(H, pos, alpha=0.4, node_size=0, width=1, edge_color='k')
nx.draw_networkx_labels(H, pos, fontsize=14)
font = {'fontname': 'Helvetica',
'color': 'k',
'fontweight': 'bold',
'fontsize': 14}
plt.title("World Chess Championship Games: 1886 - 1985", font)
# change font and write text (using data coordinates)
font = {'fontname': 'Helvetica',
'color': 'r',
'fontweight': 'bold',
'fontsize': 14}
plt.text(0.5, 0.97, "edge width = # games played",
horizontalalignment='center',
transform=plt.gca().transAxes)
plt.text(0.5, 0.94, "node size = # games won",
horizontalalignment='center',
transform=plt.gca().transAxes)
plt.axis('off')
plt.show()
Total running time of the script: ( 0 minutes 0.299 seconds)