random | 易学教程

What is a thread-safe random number generator for perl?

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问题 The core perl function rand() is not thread-safe, and I need random numbers in a threaded monte carlo simulation. I'm having trouble finding any notes in CPAN on the various random-number generators there as to which (if any) are thread-safe, and every google search I do keeps getting cluttered with C/C++/python/anything but perl. Any suggestions? 回答1: Do not use built-in rand for Monte Carlo on Windows. At least, try: my %r = map { rand() => undef } 1 .. 1_000_000; print scalar keys %r, "\n"

How to randomize if statements within android development

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问题 I am building a questionnaire type application within android and I am wondering if there is a way to randomize the final output if the if statements have the same values? In other terms I don't want one single result that occurs every time, I want the result to be randomized between 'GOOD JOB' and 'WELL DONE' does anybody know if this is possible? Here is my Code: @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity

R : Assigning students to equal groups with random sampling. Understanding rep() argument length.out to sample()

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问题 I have 33 students I want to sort into groups of 6 (or as close as possible) on 5 different occasions. So I assign a number between 1 and 6 to the students on different occassions. I've managed the following: studentlist <- data.frame(seq(1:33)) studentlist$Occassion1 <- sample(factor(rep(1:6, length.out=nrow(studentlist)), labels=paste0(1:6))) studentlist$Occassion2 <- sample(factor(rep(1:6, length.out=nrow(studentlist)), labels=paste0(1:6))) studentlist$Occassion3 <- sample(factor(rep(1:6,

How do I solve this problem with the output being unable to get the statement of the input(myflush) in coding “Random Number Guessing” in C

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问题 I tried going beyond just guessing random numbers. Basically, the program should be made to show like this : insert a number : 70 bigger than 0 smaller than 70. insert a number : 35 bigger than 35 smaller than 70. insert a number : 55 bigger than 55 smaller than 70. insert a number : 60 bigger than 55 smaller than 60. insert a number : 57 You got it right on your 5th try! I had some problems, but already through brilliant people in stackoverflow, I am able to get all the results I wish, but

Random number generator not random in a batch file

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问题 Trying to generate a random number and use it for variable value in Windows batch script file. Maybe I am missing something very basic, but something is not working here for me. Created a batch file named random_test.bat with the following content. SET rnumber=%random% echo %random% pause Running the file consecutively three times produces the following set of outputs: One C:\Users\user\Desktop>SET rnumber=28955 C:\Users\user\Desktop>echo 20160 20160 C:\Users\user\Desktop>pause Press any key

Guarantee a specific number is in a random number set

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问题 I have written code which randomly generates number and stores them in a hashset to prevent duplicates. However, each time i run the generator i need to generate a specific number as well as some other numbers and then store all the values including the number i wanted generated stored in a hashset in a random order. What would be the best way to do this? 回答1: A series of values with no repeats generally means a shuffle because a value can repeat in a series of random values. I dont know what

08.模型集成

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机器学习实战教程（十）：提升分类器性能利器-AdaBoost 模型融合方法总结机器学习模型优化之模型融合 xgboost lightgbm 文章目录集成方法 1、Bagging 2、Boosting 3、Bagging、Boosting二者之间的区别 4、AdaBoost 1) 计算样本权重 2) 计算错误率 3) 计算弱学习算法权重 4) 更新样本权重 5) AdaBoost算法 5.实例 Bagging Adaboost 集成方法将不同的分类器组合起来，而这种组合结果则被成为集成方法 (ensemble method)或者元算法 (meta-algorithm)。集成方法主要包括 Bagging 和 Boosting 两种方法，Bagging和Boosting都是将已有的分类或回归算法通过一定方式组合起来，形成一个性能更加强大的分类器，更准确的说这是一种分类算法的组装方法，即将弱分类器组装成强分类器的方法。 1、Bagging 自举汇聚法（bootstrap aggregating），也称为bagging方法。Bagging对训练数据采用自举采样（boostrap sampling），即有放回地采样数据，主要思想：从原始样本集中抽取训练集（每次都是从训练集中做有放回的随机采样）。每轮从原始样本集中使用Bootstraping的方法抽取n个训练样本

Default random 10 character string value for SQL Server column

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问题 I have a column rndm in my table [guests]. Now, for the field Default value or Binding for the table, whenever a new row is inserted I want to automatically insert a 10-character random string into this column as the default value. This random string may not contain special characters, only characters from a-zA-Z0-9 . What is the best approach to achieve this? To be clear: I don't want to generate this random string in my .NET code, I want it to be generated within SQL Server. And I want to

Select random object from list c#

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问题 I am making a black jack game (more complicated than it needs to be) and I believe I have setup a Dealer class, and then a game class which has a list of Dealers from in it. see below. Dealer Class namespace BlackJackClassLibrary { public class Dealer { public string Name { get; set; } public int Endurance { get; set; } } } Game Class namespace BlackJackClassLibrary { public class Game { public List<Dealer> Dealers { get; set; } } } And then finally I have a method in my Program which adds

Select random object from list c#

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