在 Matlab 中计算二维点列表的熵 [英] Calculate the entropy of a list of 2D points in Matlab

问题描述

我有一个像这样的数组中的点列表

I have a list of points in an array like this

points = [[1,2];[2,5];[7,1]...[x,y]]

x 在 0 到 1020 之间，y 在 0 到 1920 之间.

The x is between 0 and 1020 and y is between 0 and 1920.

如何在 Matlab 中计算点数组的熵?

How can I calculate the entropy of the points array in Matlab?

非常感谢！

推荐答案

我假设您想将每个 [x,y] 点视为一个数据点.让我们定义一些示例数据:

I assume you want to consider each [x,y] point as one data point. Let us define some exemplary data:

A = [[1,2];[2,5];[7,1];[1,2]];

首先我们给相等的点相等的标识符，我们可以使用

First we give equal points equal identifiers, we can do this using

[~,~,ic] = unique(A, 'rows');

然后我们计算频率以及每个标识符的概率:

Then we compute the frequency and with that the probability of each identifier:

[frequency, ~] = histcounts(ic,max(ic));
probability = frequency/sum(frequency);

有了这个，我们可以立即计算熵:

With this we can immediately compute the entropy:

entropy = -sum(probability .* log(probability))

(确保使用正确的对数，不同的字段通常使用不同的底数.)

(Make sure you use the right logarithm, different fields conventionally use different bases.)

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