How to get value from string II = strcat('A', num2str(la));

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Ole 2016-3-11

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此问题的直接链接

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编辑： Stephen23 2019-6-19

I want to plot few matrices A1 A2 A3 A4 A5 and call them in loop to make a movie. I am trying to make a string II = strcat('A', num2str(la)); but I can not get the values of the previously defined A1 matrix ?

The code below returns an error that II must be a matrix but is string A1 with no values.

A1 = rand(10,10); A2 = rand(10,10); A3 = rand(10,10); A4 = rand(10,10);  A5 = rand(10,10); 
for la = 1 : 5
    II = strcat('A', num2str(la));
    pcolor(II)
    shading interp 
    end

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Stephen23 2016-3-12

编辑：Stephen23 2019-6-19

And note that you should not create numbered variables and then try to loop over them. Put all of your data into one variable (an ND array perhaps) and then loop over the dimensions of that array.

The idea of looping over separate numbered variables often occurs to beginners, but this is a slow, buggy, and obfuscated way to code:

https://www.mathworks.com/help/matlab/matlab_prog/string-evaluation.html

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

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Answer 1

Image Analyst 2016-3-11

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/272933-how-to-get-value-from-string-ii-strcat-a-num2str-la#answer_213288

在 MATLAB Online 中打开

pcolor takes numbers, not character arrays, so why are you trying to create a character array?

And did you know that pcolor does not show you the last row or column? Use imshow instead

wideImage = [A1,A2,A3,A4,A5];
imshow(wideImage, []);

No for loop needed at all.

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Ole 2016-3-11

Thanks. This displays 5 matrices next to each other. How can be used to plot in a video one A matrix at a time ?

Image Analyst 2016-3-11

ExtractMovieFrames.m

If you want a video of this, you'll have to make up an image first. Then use text() to display text over the image. Then use VideoWriter to write the image frames to a video file, like in the attached example.

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