random

Ruby: Using rand() in code but writing tests to verify probabilities

由 余生长醉 提交于 2020-01-03 08:50:03
问题 I have some code which delivers things based on weighted random. Things with more weight are more likely to be randomly chosen. Now being a good rubyist I of couse want to cover all this code with tests. And I want to test that things are getting fetched according the correct probabilities. So how do I test this? Creating tests for something that should be random make it very hard to compare actual vs expected. A few ideas I have, and why they wont work great: Stub Kernel.rand in my tests to

std::default_random_engine generates the same values even with changing seed?

由 亡梦爱人 提交于 2020-01-03 08:42:12
问题 I'm trying to implement a class that will serve as sort of a wrapper for the random library so I can use its objects and functions in (I think) a more intuitive way elsewhere in my code. In my header I have something like this: class RandomDevice{ private: unsigned long rand_seed; default_random_engine engine; public: RandomDevice(unsigned long n); int randInt(int min, int max);}; And then in the .cpp file I implement those two functions (constructor and randInt) like so: RandomDevice:

How to generate a random number with equal probability in a given interval

由 白昼怎懂夜的黑 提交于 2020-01-03 05:41:05
问题 I tried a lot but could not get a solution for this problem Function returns numbers in range [1,6] with equal probability. You can use library's rand() function and you can assume implementation of rand() returns number in range number in range [0,RAND_MAX] with equal probability. 回答1: We'll do this in multiple steps. You need to generate a number in the range [1, 6] , inclusive. You have a random number generator that will generate numbers in the range [0..RAND_MAX] . Let's say you wanted

Image is not displayed when parent image is clicked

由 这一生的挚爱 提交于 2020-01-03 05:35:09
问题 Functionality: When user enters the first page, the primary images are randomised and displayed. Therefore, when user clicks on the primary image (1st image), a secondary image (a 2nd image) will be displayed. The secondary image is an extension to the 1st image, therefore, for e.g, when a user clicks on the 1st image of an apple, the second image of a worm is displayed. What I have done: I have set both the 1st images and 2nd images into a set of an array. Secondly, the array of 1st image is

Shuffle an array of int in C with - without while loop

由 大城市里の小女人 提交于 2020-01-03 05:29:07
问题 I want to Shuffle an array of ints, the array is sorted and its size in n, values are 1 - n. I Just want to avoid using a while loop in order to make sure the rand() doesn't give me the same index. the code looks somthin like this: void shuffleArr(int* arr, size_t n) { int newIndx = 0; int i = 0; for(; i < n - 1; ++i) { while((newIndx = i + rand() % (n - i)) == i); swap(i, newIndx, arr); } } The for loop goes until n-1, so for example in the last run it has 50/50 chance of being equal to i. I

【shoriken特效】形状

由 泄露秘密 提交于 2020-01-03 05:25:15
发射器的形状： 球形，就是向四面八方发射，所以第一个值就是半径，如果你想要以一个点来发射，那么半径的值就要小一点。 EmitFormShell 从外面发射，就是说如果你当前的半径是5，那边5以内都不会有粒子发射的。 randomDirection 随机发射，发射出去的位置会有随机的变化。 将粒子设置成从外面发射，然后在将速度调成负值就能实现蓄力聚拢的效果了。 HemiSphere半圆形，适合做建起的水花和碎片 Cone锥形，Angle是角度，Radius半径，发射类型有Base基础的，baseShell沿着表面的，Volume体积的，VolumeShell。 Box,mesh没什么好说的 Velocity over Lifetime 控制存活时的运动轨迹，比方说设置了左右移动的动画，所以粒子都会在自己存活的时候完成这样的动。 Limit Velocity over Lifetime 粒子存活时限速度 Force over Lifetime 控制存活时的力 Color over Lifetime 控制存活时的颜色 Color by speed 颜色根据速度而变化，比方说设置红到蓝，值是o-10,则速度为0的时候粒子是红色 速度是10的时候是蓝色。比方说蓝色的粒子掉落到地上后会变成红色。 Size over Lifetime 在存活的时候控制粒子的大小 Size by speed

粒子系统模块

由 谁说胖子不能爱 提交于 2020-01-03 05:23:09
原地址：http://game.ceeger.com/Manual/ParticleSystemModules40.html This page is dedicated to individual modules and their properties. For introduction to modules see this page 该页专门介绍单个模块和他们的属性。介绍模块请看 这一页 。 Initial Module 初始化模块 This module is always present, cannot be removed or disabled. 这个模块总是存在的，不能删除或禁用。 Duration 持续时间 The duration the Particle System will be emitting particles. 粒子系统发射粒子的持续时间 Looping 循环 Is the Particle System looping. 粒子系统是否循环 Prewarm 预热 Only looping systems can be prewarmed which means that the Particle System will have emitted particles at start as if it had already emitted

Python - generate same random numbers

由 怎甘沉沦 提交于 2020-01-03 05:18:52
问题 def main(): x = [randint(1,100) for i in range(1,100)] return x This returns 100 random numbers btw 1 and 100. Each time I call the function, it returns a different sequence of numbers. What I want to, is to get the same sequence of numbers each time. maybe saving the results into sth? 回答1: You can provide some fixed seed. import random def main(): random.seed(9001) x = [random.randint(1,100) for i in range(1,100)] return x For more information on seed: random.seed(): What does it do? 回答2:

Cache images on php script

由 早过忘川 提交于 2020-01-03 05:12:10
问题 I am using this great randomizer code found here: http://alistapart.com/article/randomizer , but the images are not saved on the browser's cache which means they refresh whenever the site reloads. Is it possible to keep the images cached on the following code? The reason I am using this script is that php parse on css doesn't work on my server for some reason. <?php $folder = '.'; $extList = array(); $extList['gif'] = 'image/gif'; $extList['jpg'] = 'image/jpeg'; $extList['jpeg'] = 'image/jpeg

Flexslider Start at a random slide and then continue loading sequentially

由 纵然是瞬间 提交于 2020-01-03 03:32:11
问题 I am using Flexslider - http://www.woothemes.com/flexslider/ and I have a slider setup with 37 slides in it (yes I know this is ridiculous). I need a way where when the page loads, it randomly picks a slide between slide 1 and slide 37, and then it continues on squentially from there. For example: The page loads and it randomly picks slide # 17. The next slide to appear after slide 17 should be 18, then 19, then 20 and so on. The next time the page loads it randomly picks another slide. Say
订阅 random