Matlab-计算向量中每个元素的概率 [英] Matlab - computing the probability of each element within a vector

问题描述

我有一个向量y，它可能具有以下形式:

I am having a vector y which may have the following form:

y = [1 1 1 1 2 2 2 2 1 1 3 3 4 5]

我想将概率附加到y中的每个元素，因为它是由随机变量生成的.在这种情况下，元素1的概率为6/14，元素2的概率为4/14，元素3的值为2/14，元素4和5的值为1/14.

And I want to attach a probability to each element within y as it would've been generated by a random variable. In this case, the element 1 would have the probability 6/14, the element 2 would have the probability 4/14, the element 3 the value 2/14 and the elements 4 and 5 the value 1/14.

基本上，结果应如下所示:

And basically, the result should look like:

prob_y = 1/14 * [6 6 6 6 4 4 4 4 6 6 2 2 1 1]

有没有没有任何for或while循环的方法?

Is there a way of doing this without any for or while loops?

推荐答案

输入向量中的唯一元素可以使用 ARRAYFUN 和

The unique elements in your input vector can be determined using the UNIQUE function. You can then get the desired output using ARRAYFUN and an anonymous function that checks the number of each unique element in your input vector:

>> y = [1 1 1 1 2 2 2 2 1 1 3 3 4 5];
>> prob_y = arrayfun(@(x)length(find(y==x)), unique(y)) / length(y)

prob_y =

    0.4286    0.2857    0.1429    0.0714    0.0714

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