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Semaphore Semaphore class in threading module implements semaphore object, which can be used to control the number of threads obtaining resources. The acquire() and release() methods can be used as the context manager of the with statement. The acquire() method is called when entering, and release() is called when exiting. Semaphore is simila ...

This article mainly introduces the detailed explanation of Python function definition and parameter transmission methods (4 kinds). The example code in this article is very detailed, which has certain reference and learning value for everyone's study or work. Friends in need, let's learn together with Xiaobian 1, Elementary knowledge of functi ...

Semaphores, in other words, control the number of concurrent threads, which is the number of concurrent threads in turn See the example: import threading # Import module import time # Import module class Exam(threading.Thread): # Create class def __init__(self, num): # initialization super(Exam, self).__init__() # Parent cl ...

1. KNN Algorithm principle: k elements are randomly selected from D as the respective centers of k clusters;Calculate the dissimilarity of the remaining elements to the center of k clusters, and classify these elements into the cluster with the lowest dissimilarity;According to the clustering results, the respective centers of k clusters are ...

Foreword In the web crawler, some websites will set anti crawler measures. The server will detect the number of requests of an IP in unit time. If it exceeds this threshold, it will directly refuse service and return some error messages, such as 403 Forbidden, "your IP access frequency is too high", which means that the IP is blocked ...

I. contour detection Although edge detection can detect edges, its edges are not continuous. The image contour is used to detect a whole for subsequent processing. opencv provides two functions to complete these operations: findContours(): this function can find contours drawContours(): draw contours The difference between contour and edge is t ...

The content of this article comes from learning MIT open course: univariate calculus - correlation rate - Netease open course 1, Examples of best value problems 1. Cut a line with a length of 1 into 2 segments, circle each segment into a square, and find the maximum area that can be obtained , Calculate both ends: Therefore, when t ...

Classification method based on probability theory: Naive Bayes Advantages: it is still effective in the case of less data (but the accuracy is also inexhaustible), and can deal with multi category problems. Disadvantages: it is sensitive to the way data is input. Applicable data type: nominal data. Pre knowledge: conditional probability, Bay ...

preface   I finally finished my final homework, I can't catch me (No. last time I talked about solving linear equations by LU decomposition, but sometimes when the equations are incompatible, the conventional method will fail. At this time, we can use the least square method. Of course, for matrix fitting, we can directly calculate th ...

1. Description This note is used to explain in detail how to convert classes in c + + into classes that can be used directly in the python environment. 2. Examples A simple c + + class RealWorld is defined here, including public, private members and public member functions. In this example, we will show how to convert the member functions an ...