uniform_int_distribution在这里使用错误？ （我的结果似乎不均匀分布） [英] uniform_int_distribution used wrong here? (my results seem not equally distributed)
问题描述
版本3 将发电机移动到类中。
Version 3 Moved generator into a class. Is my new random number generation technique correct this time?
template<typename T = int>
class MyRandomGenerator
{
public:
MyRandomGenerator()
{
std::random_device rd;
gen = std::mt19937{rd()};
}
T getNumber(const T& From, const T& To)
{
std::uniform_int_distribution<T> dist(From, To);
return dist(gen);
}
private:
std::mt19937 gen;
};
在这里我的新位置计算器：
And here my new position calculators:
auto calculate_x_position = [&]() ->sf::Uint32 {return RandGen.getNumber(0, W - 1); };
auto calculate_y_position = [&]() ->sf::Uint32 {return RandGen.getNumber(0, H - 1); };
与前面相同的模式/问题：
Same pattern/problem as before:
版本2 每秒创建〜3张地图每张地图10.000颗星。结果仍然是一样的。此外，它更清楚的是，有一个枢轴到地图的顶部。示例：
Version 2 Creating ~3 maps per second of 10.000 stars per map. The outcome is still the same. Moreover, it gets even more clear that there is a pivot to the top of the maps. Example:
原始问题：
i尝试绘制简单的星空图。为此，我首先计算星星的x和y位置。 X和Y在窗口的宽度和高度范围内。
Original Question: i went into trying to draw a simple star map. For this i first calculate the x and y position for the stars. X and Y are within the range of width and height of the window.
这是我的随机数生成函数：
This is my random number generating function:
template<typename T>
T getRandomNumberBetween(const T& Min, const T& Max)
{
static std::random_device rd;
static std::uniform_int_distribution<T> dist{Min, Max};
return dist(rd);
}
我这样使用：
auto calculate_x_position = std::bind(inc::getRandomNumberBetween<sf::Uint32>, 0, Width-1);
auto calculate_y_position = std::bind(inc::getRandomNumberBetween<sf::Uint32>, 0, Height-1);
x = calculate_x_position(); //...
但是当我绘制我的地图一遍又一遍在我看来，是大多数星星倾向于的地方。例如。
But as i draw my map over and over again it seems to me that there is a pivot to where most stars tend to be. E.g. the majority of stars are in the upper half of my window.
例如：
我使用错误或有错误的期望这里？因为这里它说：
Am i using it wrong or having a wrong expectation here?... Because here it says:
此分布在范围[a，b]中生成随机整数，其中每个
可能值具有相等的生成可能性。
This distribution produces random integers in a range [a,b] where each possible value has an equal likelihood of being produced.
种类问题
推荐答案
您将在屏幕的每个象限获得相等的金额;这意味着每个点出现的机会均等。所以，如果你做一个简单的50:50的试验，这并不意味着你会得到50:50的结果。
Uniform distribution does not specifically mean that you will get an equal amount in each quadrant of the screen; It means that there is an equal chance of each point appearing. So if you do a simple 50:50 trial, it does not mean you will get 50:50 results.
但是如果你做了一个测试与说100万颗星很可能它们将几乎均匀分布。对我来说，这似乎是样本大小的错误
However if you did a test with say 1,000,000 stars it is very likely that they will be nearly uniformly distributed. To me this seems like an error in sample size
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