How to save a data when something happens

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mahdi safarzadeh 2013-11-17

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https://ww2.mathworks.cn/matlabcentral/answers/106487-how-to-save-a-data-when-something-happens

评论： Image Analyst 2013-11-18

Hello everybody, I am receiving 100 symbols, with values starting from 0 and go to 1. The scenario is like this.

 for i=1:100
    if Symbolvalue >= 0.5
        Nuberofsymbolvalue=i;  
    end;
 end;

I need to save the the first i in which I go above 0.5

Thanks in advance.

回答（3 个）

Image Analyst 2013-11-17

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https://ww2.mathworks.cn/matlabcentral/answers/106487-how-to-save-a-data-when-something-happens#answer_115493

编辑：Image Analyst 2013-11-17

在 MATLAB Online 中打开

if symbolValue > 0.51
  savedSymbolValue = symbolValue;
  % Optionally save to a mat file
  save(yourMatFileName, 'savedSymbolValue');
end

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mahdi safarzadeh 2013-11-18

Thanks a lot for your answer. the find() function solution is way simpler and i am gonna try to use it in my codes. Thanks a agin.

Image Analyst 2013-11-18

Please mark the best answer as "Accepted" if you're done with this topic. Thanks.

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Umair Nadeem 2013-11-17

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编辑：Umair Nadeem 2013-11-17

在 MATLAB Online 中打开

you can use this

index = 1;
for i = 1:100
    if SymbolValue >= 0.5
       NumberofSymbolValue[index] = i;
       index += 1;
     end
end
Valueoffirst_i = NumberofSymbolValue[1];

The first value in array NumberofSymbolValue will show the first i

Hope it helps

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Image Analyst 2013-11-17

编辑：Image Analyst 2013-11-17

在 MATLAB Online 中打开

How did it work? Are you programming in C? MATLAB doesn't use [] around array indexes and doesn't have the += operator. Plus, his solution could be done with a non-looping simple call to find like Walter and my solution.

allHighSymbolIndexes = find(Symbolvalue >= 0.5)

mahdi safarzadeh 2013-11-18

of course I changed the C to Matlab code. the "find()" function solution is way simpler, I am gonna try to use it in my codes. But Umair's solution worked for may case. Thanks anyway.

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Walter Roberson 2013-11-17

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https://ww2.mathworks.cn/matlabcentral/answers/106487-how-to-save-a-data-when-something-happens#answer_115499

在 MATLAB Online 中打开

find(Symbolvalue >= 0.5, 1, 'first')

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mahdi safarzadeh 2013-11-17

Thanks a lot Walter, your solution looks really tempting but I dont know why it didnt work for my case! anyway, thanks a lot.

Image Analyst 2013-11-17

在 MATLAB Online 中打开

Just assign the output to something:

firstHighSymbolIndex = find(Symbolvalue >= 0.5, 1, 'first')
theFirstHighSymbol = Symbolvalue(firstHighSymbolIndex);

We don't know why it didn't work because you didn't show your code. The code you used (a for loop) is not vectorized and not as MATLAB-ish but is probably still fast enough.

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