If statement working partially

Question

Gonzalo Guerrero 2022-6-21

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1744575-if-statement-working-partially

评论： Voss 2022-6-22

Hi,

I have been havin problems with the following if statment. My data loads in a loop, which will run depending on the if statment. When it comes to the elseif everything run very smoothly, however, when it comes to the if conditions, it doesn't. I tried to put a keyboard afterwards, because the Time variable gave me error, although once the keyboard is placed, I can put the whole if statment and it will work. As soon as i press continue, it doesn't.

Could you help, please? :D

Thank you

while n<=length(DigMark.codes)
    if n==length(DigMark.codes)+1
        break;
    end               
    while nn<=4
        if n==length(DigMark.codes)+1
            break;
        end
        
        if nn==4
            n=n+1;
            nn=1;
            continue;
        end
        
        if DigMark.codes (n) == 65 || DigMark.codes(n)== 67 || DigMark.codes(n)== 68 ||...
                DigMark.codes(n)== 69 && DigMark.codes(n+1)~= 88
            
            Times = find(EMG{nn}.times > DigMark.times(n)-.0004& EMG{nn}.times < DigMark.times(n)+.0004);
            Times=Times(1);
            Time=EMG{nn}.times(Times);
            Code= DigMark.codes(n);
            ValuesEMG=(EMG{nn}.values(Times:Times+316));           
            CalibrateEMG=(0-mean(EMG{nn}.values(Times-316:Times)));            
            ValuesEMG=(ValuesEMG+CalibrateEMG);            
            P2PEMG= max(ValuesEMG(48:179))-min(ValuesEMG(48:179));
            RMSEMG=rms(EMG{nn}.values(Times-316:Times));
            .
            .
            .
            
            nn=n+1;
            
            
        elseif DigMark.codes(n)==66 || DigMark.codes(n)== 70 || DigMark.codes(n)== 71 && DigMark.codes(n+1)~= 88
            
            times = find(EMG{nn}.times > DigMark.times(n)-.0004& EMG{nn}.times < DigMark.times(n)+.0004);
            times=times(1);
            Time=EMG{nn}.times(times);
            Code= DigMark.codes(n);
            ValuesEMG=(EMG{nn}.values(times:times+161));           
            CalibrateEMG=(0-mean(EMG{nn}.values(times-314:times)));            
            ValuesEMG=(ValuesEMG+CalibrateEMG);            
            P2PEMG= max(ValuesEMG(16:end))-min(ValuesEMG(16:end));            
            RMSEMG=rms(EMG{nn}.values(times-316:times));            
            .
            .
            .
            
            nn=nn+1;
            
            
        else
            n=n+1;
            nn=1;
            
        end
        
    end
end 

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Stephen23 2022-6-22

在 MATLAB Online 中打开

Replace

x == 65 || x == 67 || x == 68 || x == 69 && y ~= 88

with

ismember(x,[65,67:69]) && y ~= 88

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Answer 1

Voss 2022-6-21

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1744575-if-statement-working-partially#answer_990215

在 MATLAB Online 中打开

Part of the problem might be the usage of || and &&.

In MATLAB, && takes precedence over ||, so an expression like this:

x == 65 || x == 67 || x == 68 || x == 69 && y ~= 88

is interpreted as this:

x == 65 || x == 67 || x == 68 || (x == 69 && y ~= 88)

but I think you probably mean this:

(x == 65 || x == 67 || x == 68 || x == 69) && y ~= 88

Here's a concrete case where it makes a difference:

x = 65;
y = 88;
disp( x == 65 || x == 67 || x == 68 || x == 69 && y ~= 88 )
   1
disp( (x == 65 || x == 67 || x == 68 || x == 69) && y ~= 88 )
   0

Another potential problem is that you let n go up to length(DigMark.codes) but then try to access DigMark.codes(n+1).

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Gonzalo Guerrero 2022-6-22

Thanks for your answer!

I considered that too, but It is weird that the line of elseif works, but then the if doesn't...

I have changed the while loop for a for loop instead and now it works perfectly. It might be just the loop wasn't the right one, for some reason I don't know :S

Voss 2022-6-22

I don't think either line (if or elseif) was working as you probably intended. Maybe the elseif appeared to work for whatever values it happened to get.

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