neighbor_index = indeces(1:k_values(k)); weight = ones(1,length(neighbor_index)); if fuzzy, % originally, this weight calculation should be: % weight = distances(neighbor_index).^(-2/(m-1)); % but since we didn't take sqrt above and the inverse 2th power % the weights are: % weight = sqrt(distances(neighbor_index)).^(-2/(m-1)); % which is equaliavent to: weight = distances(neighbor_index).^(-1/(m-1)); % set the Inf (infite) weights, if there are any, to 1. if max(isinf(weight)) % warning(['Some of the weights are Inf for sample: ' ... % num2str(i) '. These weights are set to 1.']); weight(isinf(weight))=1; end end

这段代码根据排序后的索引值 `indeces`，选择前 `k_values(k)` 个邻居的索引，并将其赋值给变量 `neighbor_index`。

接下来，代码创建了一个长度为 `length(neighbor_index)` 的全一向量，并将其赋值给变量 `weight`。

如果 `fuzzy` 变量为真（即非零），则进行模糊权重的计算。在这种情况下，权重的计算公式应为 `weight = distances(neighbor_index).^(-2/(m-1))`，其中 `m` 是一个参数。

然而，由于在之前的计算中没有进行平方根操作，以及倒数的平方操作，权重的计算公式需要做相应的调整。具体来说，权重计算公式变为 `weight = distances(neighbor_index).^(-1/(m-1))`。

此外，代码检查权重是否存在无穷大的情况。如果有，则将这些无穷大的权重设置为1。这一步是为了避免权重中出现无穷大导致后续计算出错。

需要注意的是，原始代码中有一段被注释掉的警告信息，提醒一些样本的权重被设置为1。你可以根据需要取消注释并查看警告信息。

相关问题

neighbor_index = indeces(1:k_values(k)); weight = ones(1,length(neighbor_index));

这段代码根据排序后的索引值 `indeces`，选择前 `k_values(k)` 个邻居的索引，并将其赋值给变量 `neighbor_index`。

接下来，代码创建了一个长度为 `length(neighbor_index)` 的全一向量，并将其赋值给变量 `weight`。

这段代码的作用是为每个测试样本选择最近的 `k_values(k)` 个邻居，并为它们分配相同的权重。在 KNN（k-最近邻）算法中，通常使用相等权重来进行预测。因此，这里使用全一向量作为权重。

将以下python 代码转换成matlab语言：import pandas as pd def calculate_mixing_degree(target_species, neighbor_species): mixing_sum = 0 species_count = len(set(neighbor_species)) - 1 # 减去目标树的重复 for neighbor in neighbor_species: if target_species != neighbor: # 如果参照树与邻近树非同种 mixing_sum += 1 # 混交度加1 mixing_degree = mixing_sum / species_count if species_count > 0 else 0 # 计算混交度 return mixing_degree def calculate_size_ratio(target_diameter, neighbor_diameters): size_sum = 0 neighbor_count = 0 for neighbor_diameter in neighbor_diameters: if pd.notnull(neighbor_diameter): neighbor_diameters_split = str(neighbor_diameter).split(",") # 将字符串按逗号分隔成列表 for neighbor in neighbor_diameters_split: neighbor = neighbor.strip() # 去除字符串两端的空格 if neighbor != "": neighbor = float(neighbor) if neighbor < target_diameter: size_sum += 1 # 大小比数加1 neighbor_count += 1 size_ratio = size_sum / neighbor_count if neighbor_count > 0 else 0 # 计算大小比数 return size_ratio def main(): data = pd.read_excel(r"C:\Users\23714\Desktop\样地数据.xls") result = [] for index, row in data.iterrows(): tree_number = row["树编号"] target_species = row["树种"] neighbor_species = row["四邻树"].split(",") # 将四邻树字符串按逗号分隔成列表 neighbor_diameters = row[4:].tolist() # 获取从第5列开始的四邻树直径数据，并转换为列表 target_diameter = row["胸径"] mixing_degree = calculate_mixing_degree(target_species, neighbor_species) size_ratio = calculate_size_ratio(target_diameter, neighbor_diameters) result.append({"树编号": tree_number, "树种": target_species, "混交度": mixing_degree, "大小比数": size_ratio}) result_df = pd.DataFrame(result) result_df.to_excel(r"C:\Users\23714\Desktop\结果数据.xls", index=False) if __name__ == '__main__': main()

这是转换成Matlab的代码：

function mixing_degree = calculate_mixing_degree(target_species, neighbor_species)
mixing_sum = 0;
species_count = length(unique(neighbor_species)) - 1; % 减去目标树的重复
for i = 1:length(neighbor_species)
neighbor = neighbor_species(i);
if ~strcmp(target_species, neighbor) % 如果参照树与邻近树非同种
mixing_sum = mixing_sum + 1; % 混交度加1
end
end
mixing_degree = mixing_sum / species_count;
if species_count <= 0
mixing_degree = 0;
end
end

function size_ratio = calculate_size_ratio(target_diameter, neighbor_diameters)
size_sum = 0;
neighbor_count = 0;
for i = 1:length(neighbor_diameters)
neighbor_diameter = neighbor_diameters{i};
if ~isnan(neighbor_diameter)
neighbor_diameters_split = strsplit(neighbor_diameter, ',');
for j = 1:length(neighbor_diameters_split)
neighbor = strtrim(neighbor_diameters_split{j});
if ~isempty(neighbor)
neighbor = str2double(neighbor);
if neighbor < target_diameter
size_sum = size_sum + 1;
end
neighbor_count = neighbor_count + 1;
end
end
end
end
size_ratio = size_sum / neighbor_count;
if neighbor_count <= 0
size_ratio = 0;
end
end

function main()
data = readtable('C:\Users\23714\Desktop\样地数据.xls');
result = {};
for i = 1:height(data)
tree_number = data.树编号(i);
target_species = data.树种{i};
neighbor_species = strsplit(data.四邻树{i}, ',');
neighbor_diameters = data{i, 5:end};
neighbor_diameters = neighbor_diameters(~isnan(neighbor_diameters));
neighbor_diameters = cellfun(@num2str, num2cell(neighbor_diameters), 'UniformOutput', false);
target_diameter = data.胸径(i);
mixing_degree = calculate_mixing_degree(target_species, neighbor_species);
size_ratio = calculate_size_ratio(target_diameter, neighbor_diameters);
result{i} = struct('树编号', tree_number, '树种', target_species, '混交度', mixing_degree, '大小比数', size_ratio);
end
result = [result{:}];
result_df = struct2table(result);
writetable(result_df, 'C:\Users\23714\Desktop\结果数据.xls', 'FileType', 'spreadsheet', 'WriteVariableNames', true, 'Sheet', 'Sheet1');
end

if ~isempty(strfind(version, 'R20'))
main();
else
error('This code requires Matlab R2020 or later.');
end