Raphaël的博客

Understanding and being able to change environment variables can be really useful to quickly alter a program’s behavior. Usually, we can do this by just making some minor changes in the environment the programs are running in. From a command line prompt,..

日期和时间 Python内建的datetime模块提供了datetime、date和time类型。datetime类型结合了date和time，是最常使用的： In [102]: from datetime import datetime, date, time In [103]: dt = datetime(2011, 10, 29, 20, 30, 21) In [104]: dt.day Out[104]: 29 In [105]: dt.minute Out[105]: 30 根据datet

Linear algebra is linear, because it just takes input values, our a and b, and multiplies them by constants. So everything is linear. And it’s algebra, that is it’s a notation describing mathematical objects and a system of manipulating those notations. So

If you mouse over a new file, a new menu will appear that suggests the various file formats available to you. RScript and RMarkdown files are the most common file types for use, but you can also generate RNotebooks, web apps, websites or slide presentat...

In our computer, we have something called the External Data Bus or EDB.It’s a row of wires that interconnect the parts of our computer, kind of the veins in our body. When you send a voltage to one of the wires, we say the state of the wire is on, or r...

学习记录，防止遗忘 正则表达式是一个特殊的字符序列，它能帮助你方便的检查一个字符串是否与某种模式匹配。 以上方法显的非常繁琐。。。 re 模块使 Python 语言拥有全部的正则表达式功能。 re.search 扫描整个字符串，匹配成功re.search方法返回一个匹配的对象，否则返回None。 re.search(pattern, string, flags=0) ...

Some good programming resources available online: Automate the Boring Stuff with Python: This book (available online and in print) includes a lot of practical programming exercises for beginners. You can refer to this content to read more about some of the

Object-Oriented Programming Defined In object-oriented programming, concepts are modeled as classes and objects. An idea is defined using a class, and an instance of this class is called an object. Almost everything in Python is an object, including string

Source: Coursera

Common sequence operations len(sequence) Returns the length of the sequence for element in sequence Iterates over each element in the sequence if element in sequence Checks whether the element is part of the sequence sequence[i] Accesses the element at in

学习记录，防止遗忘

String operations len(string) Returns the length of the string for character in string Iterates over each character in the string if substring in string Checks whether the substring is part of the string string[i] Accesses the character at index i of the s

Pandas | 将dataframe中的series相加时，df.a+df.b没有问题，但是df.a+’,’+df.b时就报错，报错如下： TypeError: ufunc ‘add’ did not contain a loop with signature matching types dtype(’<U21’) dtype(’<U21’) dtype(’<U21’) 问题如题如图： 解决方法 将a和b由int转化为str： df.a=df.a.astype(str) df.b=d

git bash 常用命令 linux命令：意义 pwd：print work directory显示当前目录路径 ls：list列出当前目录内容 cd：change directory cd …: 返回上一级 cd ~: 返回默认工作路径 ls -l (文件路径)：显示文件内容物 ls -l 文件路径/.目标文件类型：列举在该文件路径下的目标文件及详细信息 ex:ls -l ~/desktop/.pdf mkdir 文件路径/想要创建的文件名 :在文件路径中创建新文件 ex: mkdir desktop