thuandt

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

thuandt

One of the most common tasks that requires random action is selecting one item from a group, be it a character from a string, unicode, or buffer, a byte from a bytearray, or an item from a list, tuple, or xrange. It’s also common to want a sample of more than one item.

Don’t do this when randomly selecting an element

A naive approach to these tasks involves something like the following; to select a single item, you would use randrange (or randint) from the random module, which generates a pseudo-random integer from the range indicated by its arguments:

import random
 
items = ['here', 'are', 'some', 'strings', 'of',

thuandt

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
#      Filename:  prime.py
#
#   Description:  Tìm số nguyên tố lớn nhất có 9 chữ số khác nhau
#
#       Created:  12/09/2012 06:32:33 AM
# Last Modified:  12/09/2012 06:40:49 AM

thuandt

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""Chương trình chuyển đổi từ Tiếng Việt có dấu sang Tiếng Việt không dấu
Chỉnh sửa từ mã nguồn của anh NamNT
http://www.vithon.org/2009/06/14/x%E1%BB%AD-ly-ti%E1%BA%BFng-vi%E1%BB%87t-trong-python
"""

import re

INTAB = "ạảãàáâậầấẩẫăắằặẳẵóòọõỏôộổỗồốơờớợởỡéèẻẹẽêếềệểễúùụủũưựữửừứíìịỉĩýỳỷỵỹđẠẢÃÀÁÂẬẦẤẨẪĂẮẰẶẲẴÓÒỌÕỎÔỘỔỖỒỐƠỜỚỢỞỠÉÈẺẸẼÊẾỀỆỂỄÚÙỤỦŨƯỰỮỬỪỨÍÌỊỈĨÝỲỶỴỸĐ"