choose elements from array randomly

Hi everyone

I have vector array of elements …

for example a=[1,2,3,4]

how can I choose randomly 10% of the above array????

Help me please

majid

Answer 1

[Wayne King]

You must be using an older version of MATLAB, do this instead:

   % create vector  
   a = randn(100,1);
   % determine how many elements is ten percent
   numelements = round(0.1*length(a));
   % get the randomly-selected indices
   indices = randperm(length(a));
   indices = indices(1:numelements);
   % choose the subset of a you want
   b = a(indices);

[Majid Al-Sirafi]

thank you brother

majid

Answer 2

[Azzi Abdelmalek]

 a=[1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17]
 n=length(a)
 nr=round(n/10)
 out=a(randperm(n,nr))

or if you have'nt randperm

 n=length(a);
 nr=round(n/10)
 [ ~,idx]=sort(rand(n,1));
 out=a(idx(1:nr))

[Azzi Abdelmalek]

Depends on how you want to round your percentage use, round or ceil or floor

Answer 3

[Wayne King]

One thing you can do is:

   % create vector  
   a = randn(100,1);
   % determine how many elements is ten percent
   numelements = round(0.1*length(a));
   % get the randomly-selected indices
   indices = randperm(length(a),numelements);
   % choose the subset of a you want
   b = a(indices);

[Majid Al-Sirafi]

thank you dear

but when I run this code the following error had been occured

??? Error using ==> randperm Too many input arguments.

majid

[Wayne King]

See my answer below for a use of randperm compatible with earlier versions of MATLAB