以后再也不用担心写爬虫ip被封，不用担心没钱买代理ip的烦恼了 在使用python写爬虫时候，你会遇到所要爬取的网站有反爬取技术比如用同一个IP反复爬取同一个网页，很可能会被封。如何有效的解决这个问题呢？我们可以使用代理ip，来设置代理ip池。 现在教大家一个可获取大量免费有效快速的代理ip方法，我们访问西刺免费代理ip网址 这里面提供了许多代理ip，但是我们尝试过后会发现并不是每一个都是有效的。所以我们现在所要做的就是从里面提供的筛选出有效快速稳定的ip。 以下介绍的免费获取代理ip池的方法： 优点：免费、数量多、有效、速度快 缺点：需要定期筛选 主要思路： 从网址上爬取ip地址并存储 验证ip是否能使用-（随机访问网址判断响应码） 格式化ip地址 代码如下： 1.导入包 import requests from lxml import etree import time 1 2 3 2.获取西刺免费代理ip网址上的代理ip def get_all_proxy(): url = 'http://www.xicidaili.com/nn/1' headers = { 'User-Agent': 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36', } response = requests.get(url, headers=headers) html_ele = etree.HTML(response.text) ip_eles = html_ele.xpath('//table[@id="ip_list"]/tr/td[2]/text()') port_ele = html_ele.xpath('//table[@id="ip_list"]/tr/td[3]/text()') proxy_list = [] for i in range(0,len(ip_eles)): proxy_str = 'http://' + ip_eles[i] + ':' + port_ele[i] proxy_list.append(proxy_str) return proxy_list 1 2 3 4 5 6 7 8 9 10 11 12 13 14 3.验证获取的ip def check_all_proxy(proxy_list): valid_proxy_list = [] for proxy in proxy_list: url = 'http://www.baidu.com/' proxy_dict = { 'http': proxy } try: start_time = time.time() response = requests.get(url, proxies=proxy_dict, timeout=5) if response.status_code == 200: end_time = time.time() print('代理可用：' + proxy) print('耗时:' + str(end_time - start_time)) valid_proxy_list.append(proxy) else: print('代理超时') except: print('代理不可用--------------->'+proxy) return valid_proxy_list 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 4.输出获取ip池 if __name__ == '__main__': proxy_list = get_all_proxy() valid_proxy_list = check_all_proxy(proxy_list) print('--'*30) print(valid_proxy_list) 1 2 3 4 5 技术能力有限欢迎提出意见，保证积极向上不断学习 ———————————————— 版权声明：本文为CSDN博主「彬小二」的原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接及本声明。 原文链接：https://blog.csdn.net/qq_39884947/article/Details/86609930
上传时间： 2019-11-15
上传用户：fygwz1982
使用matlab实现gibbs抽样，MCMC: The Gibbs Sampler 多元高斯分布的边缘概率和条件概率 Marginal and conditional distributions of multivariate normal distribution
上传时间： 2019-12-10
上传用户：real_
This work titled A Digital Phase Locked Loop based Signal and Symbol Recovery System for Wireless Channel is intended to serve as a document covering funda- mental concepts and application Details related to the design of digital phase locked loop (DPLL) and its importance in wireless communication. It documents some of the work done during the last few years covering rudimentary design issues, complex implementations, and fixing configuration for a range of wireless propa- gation conditions.
上传时间： 2020-05-27
上传用户：shancjb
This research work aims at eliminating the off-chip RF SAW filters from fre- quency division duplexed (FDD) receivers. In the first approach, a monolithic passive RF filter was constructed using on-chip capacitors and bondwire inductors. The bond- wire characteristics were studied in Details and the effect of mutual inductive coupling between the bondwires on the filter performance was analyzed. Based on that, a bond- wire configuration was proposed to improve the frequency response of the filter. The filter was implemented in 0.18 µm CMOS process for WCDMA applications.
标签： Interference Mitigation Techniques
上传时间： 2020-05-27
上传用户：shancjb
When we started thinking about writing the first edition of this book a few years ago, we had been working together for more than five years on the borderline between propagation and signal processing. Therefore, it is not surprising that this book deals with propagation models and design tools for MIMO wireless communications. Yet, this book should constitute more than a simple combination of these two domains. It hopefully conveys our integrated understanding of MIMO, which results from endless controversial discussions on various multi-antenna related issues, as well as various interactions with numerous colleagues. Obviously, this area of technology is so large that it is beyond our aim to cover all aspects in Details. Rather, our goal is to provide researchers, R&D engineers and graduate students with a comprehensive coverage of radio propagation models and space–time signal processing techniques for multi-antenna, multi-user and multi-cell networks.
上传时间： 2020-05-28
上传用户：shancjb
When we started thinking about writing this book, we had been working together for more than five years on the borderline between propagation and signal processing.Therefore, it is not surprising that this book deals with propagation models and design tools for MIMO wirelesscommunications.Yet, thisbookshouldconstitutemorethanasimplecombination of these two domains. It hopefully conveys our integrated understanding of MIMO, which results from endless controversial discussions on various multi-antenna related issues, as well as various interactions with numerous colleagues. Obviously, this area of technology is so large that it was beyond our aim to cover all aspects in Details. Rather, our goal has been to provide researchers, R&D engineers and graduate students with a comprehensive coverage of radio propagation models and space–time coding techniques.
标签： Communications5 Wireless MIMO
上传时间： 2020-05-28
上传用户：shancjb
Before delving into the Details of orthogonal frequency division multiplexing (OFDM), relevant background material must be presented first. The purpose of this chapter is to provide the necessary building blocks for the development of OFDM principles. Included in this chapter are reviews of stochastic and random process, discrete-time signals and systems, and the Discrete Fourier Transform (DFT). Tooled with the necessary mathematical foundation, we proceed with an overview of digital communication systems and OFDM communication systems. We conclude the chapter with summaries of the OFDM wireless LAN standards currently in existence and a high-level comparison of single carrier systems versus OFDM.
上传时间： 2020-05-31
上传用户：shancjb
Before I can present design concepts or tactical wireless communications and network challenges, I feel the need to mention the challenges of writing for a field where some information is not available for public domain and cannot be included in this book’s context. Another challenge is the use of military jargon and the extensive number of abbreviations (and abbreviations of abbreviations!) in the field. Engineering books are naturally dry, and I have attempted to make it light by presenting the concepts in layman’s terms before diving into the technical Details. I am structuring this book in such a way as to make it useful for a specialized graduate course in tactical communications and networking, or as a reference book in the field.
标签： Communications Tactical Networks Wireless and
上传时间： 2020-06-01
上传用户：shancjb
This book is about the Arduino microcontroller and the Arduino concept. The visionary ArduinoteamofMassimoBanzi,DavidCuartielles,TomIgoe,GianlucaMartino,andDavidMellis launchedanewinnovationinmicrocontrollerhardwarein2005,theconceptofopensourcehardware. There approach was to openly share Details of microcontroller-based hardware design platforms to stimulate the sharing of ideas and innovation.This concept has been popular in the software world for many years.
标签： Microcontroller Processing Arduino
上传时间： 2020-06-09
上传用户：shancjb
This book is about the Arduino microcontroller and the Arduino concept. The visionary ArduinoteamofMassimoBanzi,DavidCuartielles,TomIgoe,GianlucaMartino,andDavidMellis launchedanewinnovationinmicrocontrollerhardwarein2005,theconceptofopensourcehardware. There approach was to openly share Details of microcontroller-based hardware design platforms to stimulate the sharing of ideas and innovation.This concept has been popular in the software world for many years.
标签： Microcontroller Processing Everyone Arduino Part for
上传时间： 2020-06-09
上传用户：shancjb
