vernice的专栏

import syssys.path.insert(0, '../utils/')from sort_dictionary_by_value import sort_dictionary_by_value

################## in LaTeX, replace :^) by :$\hat{\mkern6mu}$)# replace \ by $\backslash$# replace :{ by :\{# replace $ by \$#################

Windows Platform:cd C:\Users\jack\AppData\Local\Continuum\Anaconda2\pythonw.exe C:\Users\yfeng14\AppData\Local\Continuum\Anaconda2\Scriptspip install package-nameLinux Platform:cd ~/anacon

I googled many Python methods to color countries in a world map. But most of them require additional Python packages, like cartopy, and shapelib. Because I am using Anaconda (Python 3.5) on Windows, i

The term AJAX is short for Asynchronous Javascript and XML. It uses the Javascript XMLHttpRequest function to create a tunnel between the client's browser and the server to transmit information back a

The following code works well.from urllib.request import urlopen import bs4doc= urlopen("http://www.w3school.com.cn/html/html_tables.asp")soup = bs4.BeautifulSoup(doc,fromEncoding="GB2312")a=s

I found a very useful Python package for detecting the encoding of files. It's chardet. 1. install chardetpip install chardet2. an example of how to use itPython 2import urllibrawdata

Python always round to nearest even.test_1 = np.around(3.5)test_2 = np.around(4.5)test_1 = 4test_2 = 4test_1 = round(3.5)test_2 = round(4.5)test_1 = 4test_2 = 5

Python 与 Matlab 矩阵操作对应表MatlabPythonnumel(X)X.sizesize(X, 2)X.shape[1]A.*BA*BA*BA.dot(B)X'X.conj().TX(1:5, :)X[0:5, :]X(1:2, 4:7)X[0:

import numpya = numpy.array(([3,2,1],[2,5,7],[4,7,8]))itemindex = numpy.argwhere(a == 7)print (itemindex)print a

Starting with Python 3.5, glob module supports the '**' directive, which matches any files and zero or more directories or subdirectories if the 'recursive' is set as True. The following example sho

I attempt to run a Python LDA module after 'pip install lda'. But there always occurs a weird bug: lda.py line 3 -- "no module named datasets". First, I thought the package of LDA are not installed co

Find the difference of keys between two dictionariesSuppose two dictionaries A and B. We would like to find the keys in A but not in B.Bad example:import timeA = {}B = {}for i in range(1000):

If you use Dropbox to sync files between platforms, you may face the problem of editing Python codes on Windows, but execute the code on Linux. In this case, identifying the OS type inside Python code...

import matplotlibmatplotlib.rcParams.update({'font.size': 22})

history.pushState(null, document.title, location.href); window.addEventListener('popstate', function (event) { history.pushState(null, document.title, location.href); }); window.location.ha

After registering my domain on Hostinger, I tried to connect the Hostinger MySQL database from PHP script. Be careful about the server name:<?php $servername = "localhost"; // work $servername = "

import pandas as pdimport numpy as npimport matplotlib.pyplot as pltfrom matplotlib.collections import EllipseCollectiondata = pandas.DataFrame([["A", 4, 0, 1, 27], ["B"

Examples of Python Matplotlib to plot barhttps://pythonspot.com/en/matplotlib-bar-chart/

my_dict = {'a': 0, 'b': 1, 'c': 2}# python 3.xprint (list(my_dict.keys()).index('c'))# python 2.7print (my_dict.keys().index('c'))

An example on Windows:from joblib import Parallel, delayedimport multiprocessing data = range(100) def process_task(i): print (i)if __name__ == '__main__': num_cores = multiproces

最近从Spyder转到PyCharm，对PyCharm进行配置。PyCharm共有三个版本，付费版本，community版本和education版本。首先配置PyCharm的背景，快捷键组合，视图模式和风格。使用快捷键Ctrl + "`"(该键位于键盘的左上角，和”~“同一个键位)，即可开发上图配置选项。color Scheme: 配置背景颜色code style sche

两种比较树是否相同的Python代码实现如下所示：代码1：class Node: _value = "" _left = None _right = None def hasLeftChild(self): if (self._left != None): return True else: return False def hasRightChild

Newick Format是表示树的一种方式，具体参见wikipedia https://en.wikipedia.org/wiki/Newick_format。一下代码表示了将二叉树转化成仅保留叶子节点的Newick格式。比如下图中的树转化成Newick格式为：(A,B,(C,D))实现的Python代码如下：class Node: value = "" leftChil

#法一import ospath = "C://Python34//"for file in os.listdir(path): if os.path.isfile(os.path.join(path,file))==True: if file.find('.')<0: newname=file+'.jpg' os.re

Python作为一种脚本语言，其非常适合文件级的各种操作。下面的代码可以批量删除指定文件夹下的全部特定类型（CSV类型）的文件。import sys, csv , operatorimport osimport globfor i in range(0, 20): path = "C:\\Python34\\Folder_" + str(i) for infile in glo

使用Python进行图像编程，要使用到Graphics库。Graphics库可以从http://mcsp.wartburg.edu/zelle/python/graphics.py获取。在Windows平台上将下载的graphics.py保存在C:\Python31\Lib\site-packages即可。

Google Roads API提供了强大的道路获取接口，用户只需调用相应的API就可以获取相应区域的道路坐标以及道路的限速信息。具体的调用方法如下：https://roads.googleapis.com/v1/snapToRoads?path=-35.27801,149.12958|-35.28032,149.12907|-35.28099,149.12929|-35.28144,14

Lambda表达式在Python中经常使用到，在此总结下Lambda表达式的常用方法。首先，要明白Lambda表达在Python中是作为一个匿名函数的构造器而存在。其次，要明白Lambda表达式的常用场景是Lambda表达式对应函数的使用次数非常有限（因此，没有必要专门定义一个非匿名函数），同时保证了代码的简洁性。最简单的一个Lambda表达式例子和对应的非匿名函数：f

处理csv文件时，经常用到多级或者多属性排序，我们可以使用如下方式轻松搞定多级排序。Python 2.x使用如下代码：先按照第一列即x[0]升序排序，再按照第二列即x[0]升序排序。如需降序排列，需在sorted函数体内加上reverse = True。import sys, csv , operatordata = csv.reader(open('C:\test.csv')

Static Scoping:With static scope, a variable always refers to its top-level environment. This is a propertyofthe program text and unrelated to the runtime call stack. Because matching a variable 

6/8上午chmod [auog][+-=][rwx] filechmod -R [XXX] file    //R表示递归 recursionchown target_owner filechgrp target_owner file umask与chmod功能相反 默认数值为0022umask 0002 //valid before cl

Python 2.x, not for Python 3.xsortedlist = sorted(data, key = lambda x: (x[0], int(x[6])))

使用k-means算法对数据进行聚类之后，通常需要估计一下

近日经常遇到在Linux shell中批量执行相似命令的情况。比如执行如下命令：gifsicle --delay=100 gif/App_1_hour_*_down.gif > combine_gif/App_1_hour_down.gifgifsicle --delay=100 gif/App_1_hour_*_up.gif > combine_gif/App_1_hour_up.gif

Python编程时，经常需要跳过第一行读取文件内容。比较容易想到是为每行设置一个line_num，然后判断line_num是否为1，如果不等于1，则进行读取操作。相应的Python代码如下：input_file = open("C:\\Python34\\test.csv")line_num = 0for line in islice(input_file, 1, None): line

Python处理csv文件时经常会用到讲csv文件整体读取为一个数组或者矩阵的情况，借助numpy包，可以使用如下代码简洁高效低实现：import numpymy_matrix = numpy.loadtxt(open("c:\\1.csv","rb"),delimiter=",",skiprows=0)将数组或者矩阵存储为csv文件可以使用如下代码实现：num

为加深对各种基础排序算法的理解，我基于Thomas H. Cormen等《算法导论》中的伪代码，用Python实现了冒泡排序、选择排序、插入排序、快速排序、归并排序、二分法查找算法。具体算法如下：冒泡排序：def bubbleSort(alist): for passnum in range(0, len(alist) - 1, 1): for i in

并行化处理已经成为了很多工程项目的需求。本文展示了如何使用threadpool包将普通的Python程序多线程化。import requestsimport bs4import timeimport threadpool# build data arraydata = []for e in range(10,20): data.append(str(e))def prin

最近在做一个基于文本分析的项目，需要抓取相关网页进行分析。我使用了Python的request和beautifulsoup组件包抓取和解析网页。在抓取过程中发现了很多问题，这些问题是在抓取工作开始之前，不曾预料到的。比如，由于不同网页的解析过程可能不一致，这可能导致解析失败；再比如，由于访问服务器资源过于频繁，可能会导致connection closed by remote host错误的出现。如