how to add a waitbar in while...end loop?

In my code, I did not know the precise number of loop.I use therefore while...end. In addition, I want to add a waitbar in my loop, how can it be done?

[Adam]

You will have to estimate how many iterations round the loop you expect as that is a key parameter for most progress bars. Obviously it may then jump from some semi-filled position to full (or just disappear) if it is faster than your estimate or it will sit at 100% for a while if your estimate is too low.

You can dynamically update the estimate within the loop although this can lead to progress bars that start going backwards as well as forwards which is not recommended - a pretty much guaranteed way to annoy a user and cause them to lose confidence in the software!

[Jian Wang]

Thank you for your answer.

Answer 1

[Joseph Cheng]

Depending on what your while condition is. If you are approximating maybe something like this (which converges a bit too fast to see the bar fill gradually but i think it gets the point across)

 %unknown waitbar iterations test
  n= [1 1];
  phi = 1+1/1;
  iter=1;
  h=waitbar(0,['iterations: ' num2str(iter)]);
  while phi/(n(end)/n(end-1))~=1
     n = [n n(end)+n(end-1)];
     phi = 1+1/phi;
  %    disp(phi/(n(end)/n(end-1)))
     disp([n(end)/n(end-1) phi]); 
     perc= sort([n(end)/n(end-1) phi]);
     iter = iter+1;
     waitbar(perc(1)/perc(2),h,['iterations: ' num2str(iter)])
     pause(.1);
  end
  waitbar(1,h,['completed with iterations: ' num2str(iter)])

Where depending on what the while loop condition is you may be able to fill it using a ratio of the while loop check. Or if you are using while 1 with a break then how close you are to the break condition.

Can you expand on the format of your while loop?

[Jian Wang]

Hi Joseph,

I am sorry to reply so late. My code is as following:

function threshold=MeanPStd(data)
data=reshape(data,1,[]);
mydata=data;
M=2;
N=3;
mymean=mean(mydata);
mystd=std(mydata);
elimthreshold=mymean+N*mystd;
indices=mydata>elimthreshold;
while ~isempty(indices)
    mydata(indices)=[];  
    mymean=mean(mydata);
    mystd=std(mydata);
    elimthreshold=mymean+N*mystd;
    indices=mydata>elimthreshold;   
end
threshold=mymean+M*mystd;

I hope you could help me. Thank you.

[Joseph Cheng]

well first of all you have the incorrect condition for your while. indices will never be empty.

for example:

 x=[1 2 3 4];
 indices = x>10000000000000;

will return all zeros. what you should have is

 while sum(indicies)~=0

without knowing what your data looks like it is hard to figure out how it'll converge. however if it is pretty much a normal distribution with outliers greater than 3 sigma (single sided) then you can probably see that the first iteration will get rid of the most. Everything else will then converge toward zero so you can then use something like

    waitbar(1-sum(indices)/starting,hbar,['iteration #' num2str(iter)])

See attaches test code i threw together:

    % function threshold=MeanPStd(data)
  data = randi(100,10000,1).*randi(100,10000,1).*(-1).^(randi(2,10000,1)-1);
  data = [data;randi(100000,1000,1).*(-1).^(randi(2,1000,1)-1)];
  h=histfit(data,200)

data=reshape(data,1,[]);
mydata=data;
M=2;
N=3;
mymean=mean(mydata);
mystd=std(mydata);
elimthreshold=mymean+N*mystd;
indices=mydata>elimthreshold | mydata<-elimthreshold;
iter = 1;
starting = sum(indices);
hbar=waitbar(0,'processing');
while sum(indices)~=0
    mydata(indices)=[];  
    histfig=histfit(mydata,2000);
    title(iter)
    iter=iter+1;
    pause(1)
    mymean=mean(mydata);
    mystd=std(mydata);
    elimthreshold=mymean+N*mystd;
    indices=mydata>elimthreshold | mydata<-elimthreshold; 
    waitbar(1-sum(indices)/starting,hbar,['iteration #' num2str(iter)])
end
waitbar(1,hbar,['completed in iteration #' num2str(iter)])
threshold=mymean+M*mystd;