# QA Official

### Distance Measurement Complete Edition

https://qaofficial.com/post/2019/04/18/73117-distance-measurement-complete-edition.html 2019-04-18
distance measurement Common Distance and Similarity Measure Euclidean distance defined on two vectors (two points): point xx\mathbf{x} and point yy\mathbf{y} have euclidean distances of: d_{Euclidean}=\sqrt{(\mathbf{x}-\mathbf{y})^\top (\mathbf{x}-\mathbf{y})} Minkowski distance Minkowski distance, ppp order distance of two vectors (points): d_{Minkowski}=(|\mathbf{x}-\mathbf{y}|^p)^{1/p} When p=1p=1p=1, it is Manhattan distance; when p=2p=2p=2, it is Euclidean distance. Mahalanobis distance is defined on two vectors (two points) which are in the same distribution inside.

### Explain what Java JAVAEE is

https://qaofficial.com/post/2019/04/18/68342-explain-what-java-javaee-is.html 2019-04-18
javaEE refers to java enterprise edition, java Enterprise Edition, which is mostly used for enterprise-level development, including web development, etc.JavaEE Development Association will design advanced features of java and some architectures such as spring. It needs to master relatively much. JAVA，所有的Java平台都由一个JVM和一组应用程序编程

### FASTER (cable system) RCNN/YOLO (aphorism)/SSD Algorithm Comparison

https://qaofficial.com/post/2019/04/18/73066-faster-cable-system-rcnn/yolo-aphorism/ssd-algorithm-comparison.html 2019-04-18
Anyone who has done object detection will be familiar with these three algorithms, or at least have heard of them.What are the characteristics of these three algorithms?Why can't they replace each other?Next, we will analyze it slowly. Before introducing specific algorithms, let's look at commonly used data sets. pascal voc contains 20 classesAmong them, voc 07：9,963 picture contains 24,640 marked objectsVoc 12: The test data set is not disclosed.

### Future Development Direction of Front End

https://qaofficial.com/post/2019/04/18/72971-future-development-direction-of-front-end.html 2019-04-18
reprinted to: https://jixia qinanduan.com/frontend-javascript/2016/12/11/future-frontend.html 2016 is over and the development of front-end technology will enter a new stage. What will it bring us in the future?Here, I would like to express my personal opinion. Do not spray it if you don't like it. As far as the development of the front-end mainstream technology framework is concerned, inside has developed extremely fast in the past few years. While filling in the gaps and deficiencies of the original technology framework, it is also gradually maturing.

### Image Similarity Comparison Using OpenCV Perceptual hash algorithm

https://qaofficial.com/post/2019/04/18/73041-image-similarity-comparison-using-opencv-perceptual-hash-algorithm.html 2019-04-18
--- by Liuhua.chen The author needs to deal with the problem of comparing similar pictures in the project a few days ago, and successfully completed the function development after searching data on the network and some personal research.We hereby share the following: First, the mainstream framework OpenCV is adopted, which provides the following methods for comparing pictures. 1, PSNR Peak Signal to Noise Ratio PSNR is the most common and widely used objective evaluation index for images.

### Machine Learning (Zhi-Hua Zhou) Reference Answer Chapter 10 Dimension Reduction and Metric Learning

Machine Learning (Zhi-Hua Zhou) Reference Answer Chapter 10 Dimension Reduction and Metric Learning Machine Learning (Zhi-Hua Zhou Watermelon Book) Reference Answer List http://blog.csdn.net/icefire_tyh/article/details/52064910 1. The K-neighbor classifier is programmed and compared with decision tree classification boundary on watermelon dataset 3.0 Alpha. http://blog.csdn.net/icefire_tyh/article/details/52243081 2. make err, err, err, err * respectively represent the expected error rates of the nearest neighbor classifier and Bayesian optimal classifier.

### Machine Learning-Naive Bayesian (python3 Code Implementation)

https://qaofficial.com/post/2019/04/18/73092-machine-learning-naive-bayesian-python3-code-implementation.html 2019-04-18
Naive Bayesian Harbin Engineering University -537 algorithm principle: code implementation: First import the library to be used: numpy, re, random import numpy as np import re import random Define a text_parse function and parse the document by word segmentation (dividing the whole document into words) to obtain a list of words longer than 2. def text_parse(big_string): list_of_tokens = re.split(r"\W*", big_string) # W为大写 return [tok.lower() for tok in

### Naive Bayes of Machine Learning Algorithms-Part 1

https://qaofficial.com/post/2019/04/18/73080-naive-bayes-of-machine-learning-algorithms-part-1.html 2019-04-18
Introduction I read an article earlier. A foreigner programmer wrote some amazing Shell scripts, including sending text messages to his wife after work late, automatically flushing Coffee, automatically scanning email from a DBA, etc.So I also want to do some interesting things with what I have learned.My thoughts are as follows: First I write a scrapy script to capture jokes on a website Then write a Shell script to automatically

### On the Future Prospect of IT

https://qaofficial.com/post/2019/04/18/72968-on-the-future-prospect-of-it.html 2019-04-18
IT作为一种新型产业，在短短的十几年内，已经成为我国重要的经济增长点，国家更是大力扶持，当前，我国正在深入推进“互联网+”、“大众创业万众创

### Python Basics Getting Started (2)-Usage of Command Line Parameter sys.argv[]

https://qaofficial.com/post/2019/04/18/68411-python-basics-getting-started-2-usage-of-command-line-parameter-sys.argv.html 2019-04-18
The sys.argv variable is a list of strings. sys.argv[] is used to obtain command line arguments.Remember, the name of the script is always the first parameter in the sys.argv list.Python starts counting from 0, not 1.Sys.argv[0] represent that file path of the code itself;For example, if you enter " pythontest.py-help" on the CMD command line, sys.argv[0] means " test.py" list and string are converted to each other.