How to save a data when something happens

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.

Answer 1

[Image Analyst]

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

[mahdi safarzadeh]

thanx a lot. But i dont want to save symbol value, I want to save the number in which symbol value goes above 0.5 if I use a if like this:

    if symbolvalues >= 0.5
        Numberofsymbol=n;
    end;
this way, I am not able to save the first time I go above my threshold!
I want to save the number of that symbol in which the first time go above the threshold.

[mahdi safarzadeh]

The scenario is like this, But I need to save the the first i in which I go above 0.5

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

[Image Analyst]

OK, you didn't have any explanation at first so I just went with what I could. Now that I see what you're after I recommend:

Nuberofsymbolvalue = find(Symbolvalue > 0.5, 1, 'first'); % Save the index

No loop over i is needed. If you wanted to find out the value at that index, do this:

theSymbolValue = Symbolvalue(Nuberofsymbolvalue);

though you might want to use Number instead of Nuber (unless Nuber means Number in your language)

[mahdi safarzadeh]

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]

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

Answer 2

[Umair Nadeem]

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

[Walter Roberson]

MATLAB does not use { and } for grouping: it uses "end" to mark the end of a block.

[mahdi safarzadeh]

Thanks a lot Umair, your solution worked :))))

[Image Analyst]

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]

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.

Answer 3

[Walter Roberson]

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

[mahdi safarzadeh]

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]

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.