9, Structure, unity soft, Enumeration, Macro Definition, Preprocessing9.1. Structure9.1.1, why do you need a structure?Before there was no structure, in C language, the organization of data depended on variables+arrays.At first, when it was simplest, only the basic data type (int char float double) was needed to define a single variable, and several variables were needed to define several.Later, the situation became more complicated, and sometimes many meaningful variables were needed (such as the need to store and calculate a class's student scores).
what is git?Version management tools
Why use it?It is convenient for everyone to work together to improve work efficiency.
For example, when you write a paper, you will correct many editions. How do you usually do it?
It is distinguished by naming. Version 1, Version 2, Version 3,,, etc. This version has been changed, and that version still needs to be changed. The changes have been made to a large extent.
list is a common data type in python, which is a built-in class in python and inherits from object.Next, we will introduce the common methods of list and the classes that implement the function of Class list themselves.Create listCreate an empty list list1 =  list2 = list() Create and initialize listlist1 = ['a',' b',' c', 123] # is commonly used, and the types can be inconsistent list2
concept "cross validation" is a good and accurate method for evaluating models.It divides the data set DD into k mutually exclusive subsets with similar sizes, namely d = d1d2 ... dk, didj = empty set (I ≠ j) d = d _ 1 \ bigcup d _ 2 \ bigcup ... \ bigcup d _ k, d _ I \ bigcup d _ j = empty set (i\neq j).Each subset
Quality is more important than quantity, just like a home run is better than two doubles.-Ant Financial
1, Overview In the analysis of experimental data, some algorithms need to build models with existing data, such as Convolutional Neural Network (CNN). Such algorithms are called Supervisied Learning.The data needed to build the model is called training data.
After the model is built, the correctness of the model needs to be verified by data, which is called test data.
DataFrame manually performs 10-fold cross-validation, and after sampling 10-fold, the index set of the original total data and the sampled 10-fold index set are differentiated to obtain another 9-fold index for constructing the training set. """1.10折交叉验证中数据的随机划分函数""" def cross_10folds(path,columns1): import pandas as pd #data=pd.read_csv(path)[:100] #经验
default is randomize across shards
random selection means that data is randomly taken from fragments._local: it means that the query operation will preferentially query in some fragments of the local node, otherwise, it will be queried in other nodes._primary: refers to the query only in the main fragment_primary_first: It means that the query will be first queried in the master slice. If the master slice cannot be found (hung up), the query will be made in the copy.
HTTP protocol defines the communication method of file transfer between server and client.The current version of the HTTP protocol is Http1.1.RFC 2616 describes the specific information of HTTP protocol.This protocol has become the standard between browsers and Web sites.How does the bottom layer interact when I surf the Internet?When visitors click on a hyperlink, they will submit a URL address to the browser.Through this URL address, the browser will know which website to link to and obtain the specific page file (also may be a picture, a pdf file).
JAVA syntax basics (operators, control statements) operator Arithmetic Operator:+-*/%++-- Attention to Arithmetic Operators If negative numbers are modulized, the minus sign of the modulo can be ignored, for example: 5%-2=1.But the modulus is negative is another matter. For division sign "/",there is a difference between integer division and decimal division: when dividing integers, only the integer part is retained and the decimal part is discarded. for example: int x=3510;x=x/1000*1000;What is
Java has two floating point types: float and double.Java's floating-point type has a fixed range of table numbers that is machine independent of The length of the field, The length of the field, and table number ranges.Java floating-point numbers follow the IEEE754 standard, using the Scientific notation of binary data to represent floating-point numbers. For float-type values, the first bit is the sign bit, the next 8 bits are the exponent, and the next 23 bits are the mantissa.