oversampling an array randomly

I have an array that contains 300 observations, and i would like to oversample this array to 472 observation. but i would this to be done randomly (randomly pick 172 observations and duplicate them). I've been looking online but with no luck

Answer 1

[Chunru]

a = randn(300, 1);          % original data
idx = randperm(300, 172);   % randomly pick 172 from 300
a1 = [a; a(idx)];
whos

  Name        Size             Bytes  Class     Attributes

  a         300x1               2400  double              
  a1        472x1               3776  double              
  idx         1x172             1376  double              

[Ahmed Abdulla]

Thank you thats great, I have a follow up question. If I wanted to oversample more than double the number of observations for example oversample this 300 observation array to 771 observations for example is that possible

For my current question this is sooo perfect thank youuu

[Chunru]

If you want to ensure that original 300 are always included and addtional 471 are randomly sampled, you can do the following:

a = randn(300, 1);                  % original data
idx = randi([1 300], [471 1]);      % 471 random numbers btw 1 and 300
a1 = [a; a(idx)];
whos

  Name        Size            Bytes  Class     Attributes

  a         300x1              2400  double              
  a1        771x1              6168  double              
  idx       471x1              3768  double