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"""
Pi - calculate pi over time via the monte carlo method. idea borrowed from #linode
Copyright (C) 2010 Brian S. Stephan
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
import math
import random
import re
import MySQLdb as mdb
from Module import Module
class Pi(Module):
"""Use the Monte Carlo method to approximate pi.
Each time this method is called, it calculates a random point inside a
square on the xy plane. If that point also falls within a circle bound
within that square, it is added to the count of points inside. Over time,
4 * count_inside / count approaches pi.
Idea from #linode on OFTC.
Code from http://www.eveandersson.com/pi/monte-carlo-circle
"""
def db_init(self):
"""Initialize database tables."""
# init the database if pi table doesn't exist
version = self.db_module_registered(self.__class__.__name__)
if version == None:
# create tables
db = self.get_db()
try:
version = 1
cur = db.cursor(mdb.cursors.DictCursor)
cur.execute('''
CREATE TABLE pi_log (
id SERIAL,
count_inside INTEGER NOT NULL,
count_total INTEGER NOT NULL,
time TIMESTAMP DEFAULT CURRENT_TIMESTAMP
) ENGINE=InnoDB CHARACTER SET utf8 COLLATE utf8_bin
''')
cur.execute('''
CREATE VIEW pi_latest_pi AS
SELECT count_inside, count_total
FROM pi_log
ORDER BY id DESC
''')
db.commit()
self.db_register_module_version(self.__class__.__name__, version)
except mdb.Error as e:
db.rollback()
self.log.error("database error trying to create tables")
self.log.exception(e)
raise
finally: cur.close()
def do(self, connection, event, nick, userhost, what, admin_unlocked):
match = re.search('^!pi$', what)
if match:
db = self.get_db()
try:
cur = db.cursor(mdb.cursors.DictCursor)
cur.execute('SELECT * FROM pi_latest_pi')
datum = cur.fetchone()
if datum == None:
count_inside = 0
count = 0
else:
# load values
count_inside = datum['count_inside']
count = datum['count_total']
x = random.random()
y = random.random()
inside = False
d = math.hypot(x,y)
if d < 1:
inside = True
count_inside += 1
count += 1
pi = 4.0 * count_inside / count
cur.execute('INSERT INTO pi_log (count_inside, count_total) VALUES (%s,%s)',
(count_inside, count))
db.commit()
except mdb.Error as e:
db.rollback()
self.log.error("database error doing pi stuff")
self.log.exception(e)
return self.irc.reply(event,
"database error while estimating pi: {0:s}".format(str(e)))
finally: cur.close()
return self.irc.reply(event,
"({0:.10f}, {1:.10f}) is {2}within the unit circle. "\
"pi is {5:.10f}. (i:{3:d} p:{4:d})".format(x, y,
"" if inside else "not ",
count_inside, count, pi))
# vi:tabstop=4:expandtab:autoindent
# kate: indent-mode python;indent-width 4;replace-tabs on;