matlab 信息增益代码

根据提供的引用内容，可以使用MATLAB编写一个计算信息增益的代码。下面是一个示例代码：

function [info_gain = information_gain(D, A)
% 计算数据集D的信息增益
% 输入：训练数据集D和特征A
% 输出：特征A对训练数据集D的信息增益

% 计算数据集D的经验熵H(D)
emp_ent = expEnt(D);

% 计算特征A对数据集D的经验条件熵H(D|A)
cond_ent = Ecent(A, D, emp_ent);

% 计算信息增益
info_gain = emp_ent - cond_ent;
end

function [emp_ent = expEnt(A)
% 计算列向量的经验熵
emp_ent = 0;
list = unique(A);
l = length(list);
for i = 1:l
    length_i = length(find(A == list(i)));
    p = length_i / length(A);
    emp_ent = emp_ent - p * log2(p);
end
end

function [cond_ent = Ecent(A, B, emp_ent)
% 计算经验条件熵
cond_ent = emp_ent;
length_A = length(A);
list = unique(A);
length_list = length(list);
for i = 1:length_list
    loc = find(A == list(i));
    L = length(loc);
    save = zeros(L, 1);
    for j = 1:L
        save(j) = B(loc(j));
    end
    cond_ent = cond_ent - expEnt(save) * L / length_A;
end
end

这段代码定义了三个函数，`information_gain`函数用于计算信息增益，`expEnt`函数用于计算经验熵，`Ecent`函数用于计算经验条件熵。你可以将这些代码复制到MATLAB中并进行使用。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
#### 引用[.reference_title]
- *1* [《统计学习方法》matlab计算决策树信息增益](https://blog.csdn.net/qq_45289576/article/details/127164406)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v92^chatsearchT0_1"}}] [.reference_item style="max-width: 33.333333333333336%"]
- *2* [Matlab：决策树的信息增益算法的实现](https://blog.csdn.net/weixin_51631044/article/details/123971744)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v92^chatsearchT0_1"}}] [.reference_item style="max-width: 33.333333333333336%"]
- *3* [信息增益matlab实现](https://blog.csdn.net/weixin_28771365/article/details/115936382)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v92^chatsearchT0_1"}}] [.reference_item style="max-width: 33.333333333333336%"]
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