Cell Operation

Question

Jing Hua 2012-6-26

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/42064-cell-operation

Hi,

Does anyone know how to extract all arrays in a cell without mixing them all up in a single array (cell2mat) and at the same time using the loop.

clear all, clc
%Find the Boundaries of the Ellipse
I = imread('ellipse.png');
BW = im2bw(I, graythresh(I));
figure, imshow(BW);hold on
colors=['b' 'g' 'r' 'c' 'm' 'y'];
[B,L,N,A] = bwboundaries(BW);
%Get coordinates for each boundary
K=B{3};
x3=K(1:length(K),2);
y3=K(1:length(K),1);
E=B{4};
x4=E(1:length(E),2);
y4=E(1:length(E),1);
F=B{5};
x5=F(1:length(F),2);
y5=F(1:length(F),1);
G=B{6};
x6=G(1:length(G),2);
y6=G(1:length(G),1);
H=B{7};
x7=H(1:length(H),2);
y7=H(1:length(H),1);
J=B{8};
x8=J(1:length(J),2);
y8=J(1:length(J),1);

--------------------------------------- when I put those in a loop, is appears : bad cell operation

Thanks

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Answer 1

Walter Roberson 2012-6-26

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/42064-cell-operation#answer_51805

在 MATLAB Online 中打开

colors={'b' 'g' 'r' 'c' 'm' 'y'};

Notice the change from [] to {}

Please copy the exact error message, and show which line MATLAB thinks the problem is on.

I notice that you are assuming that bwboundaries() is going to return a cell with at least 8 entries. It is not a good to assume that. If you need 8 results back, check the size of the cell array before you start indexing into it.

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Jing Hua 2012-6-26

I need Cell B, and Cell B contains 8 arrays, and each array is n*2. I need to plot first column verses second column for each array. I there a better way, cuz when I use the loop X=B{i}(1:lengthB{i},1), i=1:length(B), it returns bad cell reference operation.