jpuyy的网志

Author: jpuyy

  • Ubuntu下安装Django

    Django为流行的python web开发框架

    安装python的包管理器，easy_install

    # apt-get install python-setuptools

    可以使用下面的命令检查是否安装成功

    # easy_install --version

    显示版本信息则安装成功

    接下来使用easy_install安装Django

    # easy_install django

    使用如下命令查看django是否安装成功

    # python
Python 2.7.3 (default, Aug 1 2012, 05:14:39)
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import django
>>> django.VERSION
 (1, 4, 3, 'final', 0)

    出现版本信息，则表示安装成功。

  • python的入门的几个例子(下)

    http://jpuyy.com/2012/12/python-simple-programs-a.html

    http://jpuyy.com/2013/01/python-simple-programs-b.html

    例.20 素数筛选，生成器–Prime numbers sieve w/fancy generators

    生成从2到1000以内的素数

    import itertools

def iter_primes():
     # an iterator of all numbers between 2 and +infinity
     numbers = itertools.count(2)

     # generate primes forever
     while True:
         # get the first number from the iterator (always a prime)
         prime = numbers.next()
         yield prime

         # this code iteratively builds up a chain of
         # filters...slightly tricky, but ponder it a bit
         numbers = itertools.ifilter(prime.__rmod__, numbers)

for p in iter_primes():
    if p > 1000:
        break
    print p

    例21.xml/html解析–XML/HTML parsing

    dinner_recipe = '''<html><body><table>
<tr><th>amt</th><th>unit</th><th>item</th></tr>
<tr><td>24</td><td>slices</td><td>baguette</td></tr>
<tr><td>2+</td><td>tbsp</td><td>olive oil</td></tr>
<tr><td>1</td><td>cup</td><td>tomatoes</td></tr>
<tr><td>1</td><td>jar</td><td>pesto</td></tr>
</table></body></html>'''

# In Python 2.5 or from http://effbot.org/zone/element-index.htm
import xml.etree.ElementTree as etree
tree = etree.fromstring(dinner_recipe)

# For invalid HTML use http://effbot.org/zone/element-soup.htm
# import ElementSoup, StringIO
# tree = ElementSoup.parse(StringIO.StringIO(dinner_recipe))

pantry = set(['olive oil', 'pesto'])
for ingredient in tree.getiterator('tr'):
    amt, unit, item = ingredient
    if item.tag == "td" and item.text not in pantry:
        print "%s: %s %s" % (item.text, amt.text, unit.text)

    例28. 8皇后问题(自定义例外)8-Queens Problem (define your own exceptions)

    BOARD_SIZE = 8

class BailOut(Exception):
    pass

def validate(queens):
    left = right = col = queens[-1]
    for r in reversed(queens[:-1]):
        left, right = left-1, right+1
        if r in (left, col, right):
            raise BailOut

def add_queen(queens):
    for i in range(BOARD_SIZE):
        test_queens = queens + [i]
        try:
            validate(test_queens)
            if len(test_queens) == BOARD_SIZE:
                return test_queens
            else:
                return add_queen(test_queens)
        except BailOut:
            pass
    raise BailOut

queens = add_queen([])
print queens
print "\n".join(". "*q + "Q " + ". "*(BOARD_SIZE-q-1) for q in queens)
     例33，猜数字游戏
    import random

guesses_made = 0

name = raw_input('Hello! What is your name?\n')

number = random.randint(1, 20)
print 'Well, {0}, I am thinking of a number between 1 and 20.'.format(name)

while guesses_made < 6:

    guess = int(raw_input('Take a guess: '))

    guesses_made += 1

    if guess < number:
        print 'Your guess is too low.'

    if guess > number:
        print 'Your guess is too high.'

    if guess == number:
        break

if guess == number:
    print 'Good job, {0}! You guessed my number in {1} guesses!'.format(name, guesses_made)
else:
    print 'Nope. The number I was thinking of was {0}'.format(number)
     把代码打了一遍，还得仔细再练几遍。

  • python的入门的几个例子(中)

    接着上一个http://jpuyy.com/2012/12/python-simple-programs-a.html

    例11.三引号，while循环–Triple-quoted strings, while loop

    REFRAIN = '''
%d bottles of beer on the wall,
%d bottles of beer,
take one down, pass it around,
%d bottles of beer on the wall!
'''
bottles_of_beer = 99
while bottles_of_beer > 1:
    print REFRAIN % (bottles_of_beer, bottles_of_beer,
        bottles_of_beer - 1)
    bottles_of_beer -= 1

    例12.python中的类–Classes

    class BankAccount(object):
    def __init__(self, initial_balance=0):
        self.balance = initial_balance
    def deposit(self, amount):
        self.balance += amount
    def withdraw(self, amount):
        self.balance -= amount
    def overdrawn(self):
        return self.balance < 0
my_account = BankAccount(15)
my_account.withdraw(5)
print my_account.balance

    执行结果是10

    例13.使用unittest模块进行单元测试–Unit test with unittest

    import unittest
def median(pool):
    copy = sorted(pool)
    size = len(copy)
    if size % 2 == 1:
        return copy[(size - 1) / 2]
    else:
        return (copy[size/2 - 1] + copy[size/2]) / 2
class TestMedian(unittest.TestCase):
    def testMedian(self):
        self.failUnlessEqual(median([2, 9, 9, 7, 9, 2, 4, 5, 8]), 7)
if __name__ == '__main__':
    unittest.main()

    执行过程：将中间值计算出来与7比较，如果相等，则通过测试。

    例14.基于Doctest的测试–Doctest-based testing

    def median(pool):
    '''Statistical median to demonstrate doctest.
    >>> median([2, 9, 9, 7, 9, 2, 4, 5, 8])
    7
    '''
    copy = sorted(pool)
    size = len(copy)
    if size % 2 == 1:
        return copy[(size - 1) / 2]
    else:
        return (copy[size/2 - 1] + copy[size/2]) / 2
if __name__ == '__main__':
    import doctest
    doctest.testmod()

    执行结果：没有输出任何东西，说明中间值是7

    例15.使用itertools模块

    from itertools import groupby
lines = '''
This is the
first paragraph.

This is the second.
'''.splitlines()
# Use itertools.groupby and bool to return groups of
# consecutive lines that either have content or don't.
for has_chars, frags in groupby(lines, bool):
    if has_chars:
        print ' '.join(frags)
# PRINTS:
# This is the first paragraph.
# This is the second.

    例16.csv模块，元组拆分，内置函数cmp() — csv module, tuple unpacking, cmp() built-in

    import csv

# write stocks data as comma-separated values
writer = csv.writer(open('stocks.csv', 'wb', buffering=0))
writer.writerows([
    ('GOOG', 'Google, Inc.', 505.24, 0.47, 0.09),
    ('YHOO', 'Yahoo! Inc.', 27.38, 0.33, 1.22),
    ('CNET', 'CNET Networks, Inc.', 8.62, -0.13, -1.49)
])

# read stocks data, print status messages
stocks = csv.reader(open('stocks.csv', 'rb'))
status_labels = {-1: 'down', 0: 'unchanged', 1: 'up'}
for ticker, name, price, change, pct in stocks:
    status = status_labels[cmp(float(change), 0.0)]
    print '%s is %s (%s%%)' % (name, status, pct)

    例18. 八皇后问题，递归–8-Queens Problem (recursion)

    BOARD_SIZE = 8

def under_attack(col, queens):
    left = right = col

    for r, c in reversed(queens):
        left, right = left - 1, right + 1

        if c in (left, col, right):
            return True
    return False

def solve(n):
    if n == 0:
        return [[]]

    smaller_solutions = solve(n - 1)

    return [solution+[(n,i+1)]
        for i in xrange(BOARD_SIZE)
            for solution in smaller_solutions
                if not under_attack(i+1, solution)]
for answer in solve(BOARD_SIZE):
    print answer

  • ubuntu安装jdk7

    第一步：添加JDK7的源

    # Step 1: Add the repository for JDK 7.

    sudo apt-add-repository ppa:webupd8team/java

    第二步：更新

    # Step 2: Update

    sudo apt-get update

    第三步：安装JDK及附加组件

    # Step 3: Install JDK and associated utilities

    sudo apt-get install oracle-java7-installer

    第四步：设置默认编译器

    # Step 4: Set the default java interpreter used by the system.

    sudo update-alternatives --config java

  • python获取日期和时间的方法

    使用datetime模块

    #!/usr/bin/env python 
#-*- coding:utf-8 -*- 
#author: jpuyy date jpuyy.com

import datetime

now = datetime.datetime.now()

print
print "以str显示datetime对象"
print str(now)

print "使用实例属性"
print "今年是%d年" % now.year
print "现在是%d月" % now.month
print "今天是%d号" % now.day
print "现在%d点了" % now.hour
print "现在是%d分" % now.minute
print "当前是%d秒" % now.second
print "当前微秒值是%d, 1秒=1000000微秒" % now.microsecond

print "用strftime()显示格式化的时间"
print now.strftime("%Y-%m-%d %H:%M:%S")

    执行结果

    以str显示datetime对象
2013-01-29 16:53:12.895591
使用实例属性
今年是2013年
现在是1月
今天是29号
现在16点了
现在是53分
当前是12秒
当前微秒值是895591, 1秒=1000000微秒
用strftime()显示格式化的时间
2013-01-29 16:53:12

  • update-rc.d的用法

    update-rc.d为debian/ubuntu管理开机启动的工具，类似于chkconfig

    详细用法可查阅帮助信息

    update-rc.d --help

    查看系统当前的初始化服务

    $ ls /etc/init.d/
$ ls /etc/rc?.d

    增加或删除开机启动项

    update-rc.d -f <service> remove # 删除开机启动项服务
update-rc.d <service> start <order> <runlevels> # 新增系统启动项服务
update-rc.d <service> stop <order> <runlevels> # 停用某系统启动项

    修改启动项的启动级别

    update-rc.d [-n] name disable|enable [ S|2|3|4|5 ]

    例子

    update-rc.d php-fpm defaults # 新增系统启动项,开机即运行php-fpm服务
update-rc.d -f apache2 remove # 将apache2从启动项里删除
    update-rc.d minecraft_server defaults #开机运行minecraft
update-rc.d -f minecraft_server remove #将minecraft从启动项移除

    如将pptpd从开机启动中移除

    # update-rc.d -n -f pptpd remove
 Removing any system startup links for /etc/init.d/pptpd ...
 /etc/rc1.d/K20pptpd
 /etc/rc2.d/S20pptpd
 /etc/rc3.d/S20pptpd
 /etc/rc4.d/S20pptpd
 /etc/rc5.d/S20pptpd

    自己编译安装的想要加到开机运行服务中，还可以编写一个abc文件，具体可参考其他/etc/init.d/中的文件，放到/etc/init.d/abc

    #! /bin/sh
# /etc/init.d/abc
#
# Some things that run always
touch /var/lock/abc
# Carry out specific functions when asked to by the system
case "$1" in
 start)
 echo "Starting script abc "
 echo "Could do more here"
 ;;
 stop)
 echo "Stopping script abc"
 echo "Could do more here"
 ;;
 *)
 echo "Usage: /etc/init.d/abc {start|stop}"
 exit 1
 ;;
esac
exit 0

    给其加上权限

    chmod 755 /etc/init.d/abc

    添加启动链接即可

    # update-rc.d abc defaults