用Matlab写一个光谱分析化学成分的代码，带注释

% 读取光谱文件
data = importdata('spectrum.txt');

% 获取波长和强度数据
wavelength = data(:,1);
intensity = data(:,2);

% 绘制光谱图
plot(wavelength, intensity);
xlabel('Wavelength (nm)');
ylabel('Intensity (a.u.)');
title('Spectrum');

% 寻找吸收峰
[peak_intensity, peak_index] = findpeaks(intensity, wavelength, 'MinPeakHeight', 0.2, 'MinPeakDistance', 5);

% 输出吸收峰信息
fprintf('Found %d peaks:\n', length(peak_index));
for i = 1:length(peak_index)
fprintf('Peak %d - wavelength: %.2f nm, intensity: %.2f a.u.\n', i, wavelength(peak_index(i)), peak_intensity(i));
end

% 匹配化学成分
known_compounds = {'Benzene', 'Toluene', 'Ethanol', 'Methanol', 'Water'};
compound_wavelengths = {[254.0, 258.6, 263.0], [264.0, 268.0, 272.0], [280.0, 288.0, 294.0], [283.0, 289.0, 294.0], [186.0, 194.0, 200.0]};
match_threshold = 0.8;

matched_compounds = {};
for i = 1:length(known_compounds)
% 计算匹配度
match_score = sum(isapprox(wavelength(peak_index), compound_wavelengths{i}, match_threshold)) / length(compound_wavelengths{i});
if match_score > 0
matched_compounds{end+1} = known_compounds{i};
end
end

% 输出匹配结果
if isempty(matched_compounds)
fprintf('No matches found.\n');
else
fprintf('Matched compounds: %s\n', strjoin(matched_compounds, ', '));
end

function approx = isapprox(a, b, threshold)
% 判断两个向量中元素是否在一定阈值之内相等
approx = abs(a - b) <= threshold;
end