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### 保存图片到内存
import StringIO
output = StringIO.StringIO()
format = 'PNG' # or 'JPEG' or whatever you want
image.save(output, format)
contents = output.getvalue()
output.close()


### 保存图片到文件

omsobliga

# INSERT INTO table_tags (tag) VALUES ('tag_a'),('tab_b'),('tag_c') ON DUPLICATE KEY UPDATE tag=tag;

from sqlalchemy.ext.compiler import compiles
from sqlalchemy.sql.expression import Insert

@compiles(Insert)
def append_string(insert, compiler, **kw):
    s = compiler.visit_insert(insert, **kw)
    if 'append_string' in insert.kwargs:
        return s + " " + insert.kwargs['append_string']

omsobliga

#!/usr/bin/env python
# coding: utf-8

from tornado.web import RequestHandler


class UploadHandler(RequestHandler):

    def put(self):
        username = self.get_body_argument('username')

omsobliga

import re

# 去除所有半角全角符号，只留字母、数字、中文。
def remove_punctuation(line):
    rule = re.compile(ur'[^a-zA-Z0-9\u4e00-\u9fa5]')
    line = rule.sub('',line)
    return line

omsobliga

import csv

file_ = open('file.csv', 'r')
reader = csv.reader(file_, delimiter=',',
		    quotechar='|', quoting=csv.QUOTE_MINIMAL)
file_ = open('file.csv', 'aw')
writer = csv.writer(file_, delimiter=',',
		    quotechar='|', quoting=csv.QUOTE_MINIMAL)
file_.flush()

omsobliga

import datetime
import time

# timestamp to datetime
ts = int(time.time())
print datetime.datetime.fromtimestamp(ts).strftime('%Y-%m-%d %H:%M:%S')

# datetime to timestamp
print datetime.datetime(2017, 05, 23, 10, 30, 00).strftime('%s')

omsobliga

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# 参考资料:
# * https://en.wikipedia.org/wiki/RSA
# 
# Show RSA document:
# > from Crypto.PublicKey import RSA
# > help(RSA)

from Crypto.PublicKey import RSA

omsobliga

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# 参考资料:
# * https://en.wikipedia.org/wiki/Advanced_Encryption_Standard
# * https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation
# 
# Show AES document:
# > from Crypto.Cipher import AES
# > help(AES)

omsobliga

# python cors_server.py

import SimpleHTTPServer
class CORSHTTPRequestHandler(SimpleHTTPServer.SimpleHTTPRequestHandler):
    def send_head(self):
        """Common code for GET and HEAD commands.

        This sends the response code and MIME headers.

        Return value is either a file object (which has to be copied

omsobliga

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
用多进程模拟数据库事务在并发环境下的表现。
测试环境:
一个数据库 server, 4 核机器, 四个进程
运行结果::
    run 0 process
    run 1 process