Saving Data In A For Loop Into An Array

Question

Hans123 2019-8-20

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/476882-saving-data-in-a-for-loop-into-an-array

评论： Star Strider 2019-9-13

This seems like a basic question, but I can't seem to figure it out.

I have data for multiple spirals and I want all the x,y and z co-ordinates for each spiral in seperate arrays. I cannot preallocate because I am not aware of the size before running the code.

Would really appreciate any help on how to save my co-ordinates for each spiral in seperate arrays. The code is pasted below

clc; clear; close all
spirals = (1:10:61);
dy = max(spirals);
indent = linspace(-255+dy, 255-dy,4);
num = 1:1:7;
cla
hold on
layerheight = [1 2 4 5];
for columns=1:4
    for rows = 1:length(spirals)
        
        center = -250 + (spirals(rows))*num(rows);
        gap=layerheight(columns);
        d=layerheight(columns);
        r = spirals(rows);
        z=(linspace(0,d,10000));
        t=(40*pi/gap)*z;
        x=round(r*cos(t)+center);
        y=round(r*sin(t)+ indent(columns));
        
        plot3(x,y,z,'o','MarkerSize',2)
        %         for counter = 1:length(z)
        %             rowdata(counter) = [x(rows) y(rows) z(counter)];  %this is how I thought of saving the data, but it doesn't work
        %         end
    end
end
hold off
xlim([-255 255])
ylim([-255 255])
zlim([0 5])
grid on
xlabel('\it Increasing Radius \rightarrow')
ylabel('\it Increasing Layer Height \leftarrow')

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Answer 1

Star Strider 2019-8-20

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/476882-saving-data-in-a-for-loop-into-an-array#answer_388356

在 MATLAB Online 中打开

The easiest way would probably be to save them all in separate cell arrays, here ‘xc’, ‘yc’, and ‘zc’:

for columns=1:4
    for rows = 1:length(spirals)
        
        center = -250 + (spirals(rows))*num(rows);
        gap=layerheight(columns);
        d=layerheight(columns);
        r = spirals(rows);
        z=(linspace(0,d,10000));
        t=(40*pi/gap)*z;
        x=round(r*cos(t)+center);
        y=round(r*sin(t)+ indent(columns));
        
        plot3(x,y,z,'o','MarkerSize',2)
        %         for counter = 1:length(z)
        %             rowdata(counter) = [x(rows) y(rows) z(counter)];  %this is how I thought of saving the data, but it doesn't work
        %         end
        xc{rows,columns} = x;
        yc{rows,columns} = y;
        zc{rows,columns} = z;
    end
end