MATLAB：检查现有变量的循环

Question

我正在编写一个运行图片或乐高积木并输出其大小、形状和颜色的脚本。我们编写脚本的方式，每次使用不同乐高的新图片时，都必须清除变量的工作区。我们必须对我们通过脚本运行的每个乐高进行分类。我们将变量保存到 .mat 文件中，但似乎一次不能保存多个，因为每次运行脚本时，保存的变量都会被新值替换。我已经决定解决这个问题的最佳方法是通过循环运行 .mat 以检查现有值，如果存在值，则将值保存在现有值下方的行中。任何帮助将不胜感激，因为我是 MATLAB 的新手，尤其是循环。几天前我问了一个关于这个问题的问题，但由于一些障碍，我决定以一种新的方式解决这个问题。非常感谢。

编辑：

    if  length > 40 & length < 70
    y_length = 'Two'
    area_length = 2
elseif length > 70 & length < 90
    y_length = 'Three'
    area_length = 3
elseif length > 70 & length < 145
        y_length = 'Four'
        area_length = 4
elseif length > 150 & length < 200
    y_length = 'Six'
    area_length = 6
elseif length < 40
    y_length = 'One'
    area_length = 1
elseif length > 200
    y_length = 'Eight'
    area_length = 8
end

    if strcmp(x_length,y_length)
    shape = 'Square'
else
    shape = 'Rectangle'
end

    size = area_width * area_length ;

    %%%%%% make sure smaller dimension always first %%%%%
% width = smaller length 
% length = longer length

    Cell = {Color, size, shape, x_length, y_length};

    % for iterations 1:block_count
%     if Final = {Color, size, shape, x_length, y_length}
disp(Cell)     
 SaveData = {sprintf('%s, %d, %s, %s, %s', Color, size, shape, x_length, y_length)};
% load('Data.mat');
% 

    data = [data; SaveData];
save('Data.mat', 'SaveData'); 
if  length > 40 & length < 70
        y_length = 'Two'
        area_length = 2
    elseif length > 70 & length < 90
        y_length = 'Three'
        area_length = 3
    elseif length > 70 & length < 145
            y_length = 'Four'
            area_length = 4
    elseif length > 150 & length < 200
        y_length = 'Six'
        area_length = 6
    elseif length < 40
        y_length = 'One'
        area_length = 1
    elseif length > 200
        y_length = 'Eight'
        area_length = 8
    end

    if strcmp(x_length,y_length)
    shape = 'Square'
else
    shape = 'Rectangle'
end

    size = area_width * area_length ;

    %%%%%% make sure smaller dimension always first %%%%%
% width = smaller length 
% length = longer length

    Cell = {Color, size, shape, x_length, y_length};

    % for iterations 1:block_count
%     if Final = {Color, size, shape, x_length, y_length}
disp(Cell)     
 SaveData = {sprintf('%s, %d, %s, %s, %s', Color, size, shape, x_length, y_length)};
% load('Data.mat');
% 

    data = [data; SaveData];
save('Data.mat', 'SaveData');  



                                                                                                   This is the  bottom portion of the script, hopefully enough to give you an idea. Would it be better to change the name of Cell each time it is saved in the .mat file and -append it? Perhaps a loop to recognize the presence of a value in the existing Data.mat and placing it a row below it?

Answer 1

你仍然在艰难地前进。如果您有需要处理的n 图片列表，请添加如下循环：

for k = 1:n
   %// Process picture k, generating newCell
   %// then append newCell to the end of allCells array
   allCells(k,:) = newCell;
end

现在，如果您仍需要将这些保存到文件中，您可以只保存 allCells 并立即获取所有数据。

如果您事先没有图像列表，您仍然可以通过加载数组、添加新行然后再次保存来实现目标：

load('allCells.mat');
%// Process picture, generating newCell
allCells(end+1,:) = newCell;
save('allCells.mat',allCells);

Answer 2

一种方法是为不同的片段保存不同的文件，i.e. 每个循环迭代一个文件。

类似：

for k = 1:n

    % Do your processing here.
    % Say that the interesting variables are A, B and C.

    filename = ['Data_' num2str(k, '%06i') '.mat'];
    save(filename, 'A', 'B', 'C');

end

使用这种方法，运行脚本的文件夹将包含名为 Data_000000.mat、Data_000001.mat、... 的 n 数据文件，对应于 n 迭代。

如果您希望拥有一个 mat 文件，那么通常最好在循环后只保存一次。例如：

for k = 1:n

    % Do your processing here.
    % Say that the interesting variables are A, B and C.

    A(k) = ....;        
    B(k) = ....;
    C(k) = ....;

end

% Save the results
save('Data.mat', 'A', 'B', 'C');

最好的，