Programmer Group

An introduction We learn variables so that the computer can remember a certain state of things like people, and the value of variables is used to store the state of things. Obviously, the state of things is divided into different types (such as people's age, height, position, salary, etc.), so the value of variables should also have dif ...

pandas notes 007 7, Hierarchical index import pandas as pd import numpy as np 1. Hierarchical indexing 1.1 Series When creating a Series, use Index to specify the internal and external indexes. The first inner list is the outer Index, and the second inner list is the inner Index. data = pd.Series(np.random.randn(9), i ...

The Hanoi Tower problem is a mysterious problem. Today, let's untie its mysterious veil! First, please look at the question Title Description The tower of Hanoi is an ancient mathematical problem: There are three poles A, B and C. There are n (n > 1) perforated discs on rod A, and the size of the disc decreases from bottom to top. It is req ...

1, Process oriented and object oriented The programmer has changed from a process oriented executor to an object-oriented commander 2, Creation and use of classes and objects Class definition Modifier keyword class name{ Properties and fields; method(); } //For example, we create a Person class class Person{ //Human char ...

preface python is an interpretative and object-oriented programming language, which can be applied to many life and work scenes to meet people's different needs. MySQL is an open source and free relational database, which is deeply trusted by users and enterprises. However, the establishment of database (or table) and the use of operati ...

lab1—util Before we begin, it is necessary to understand how the parameters we enter on the command line are passed to the program. For this purpose, I refer to the content of csapp. When you input a line of command string in the command line and press enter, the shell program first parses the line of command string you input, and the parser ...

Some development and treatment of knapsack problem Packing problem Title Description: There is a box with a capacity of V and n items at the same time. Each item has a volume (positive integer). It is required to take any number of n items into the box to minimize the remaining space of the box. Core idea \(f[i] \) record the maximum capacity w ...

1. Introduction to FileUtils File IO is the basic API that we often use in our daily projects. Common IO read and write operations base class byte streams InputStream and OutputStream, character stream Reader and Writer already cover common API functions in our daily project development. For a specific basic review, see a cdsn blog post: The di ...

2021SC@SDUSC Catalog 1. Write before 2. Design Mode - Abstract Factory 3. ConnectionServer Inheritance Level 4. ConnectionServer and its Grandfather Key Sources 1. Write before         In the previous blog, we learned where to send socket handles after ServerSocket listened for client socket connections. We set up a ...

  Ladies and gentlemen, we introduced NSMutableData in the Foundation framework in the previous chapter, and NSFileManager in the Foundation framework in this chapter. NSFileManager is a file related class that provides methods related to file operation. Next, we will introduce how to use these methods to operate files. The files mentioned ...