Breaking down a large array

1 view (last 30 days)
Senaasa
Senaasa on 23 May 2013
Hi,
I have a large array (nx1) of values that I'd like to break up into a new array. This new array takes the first 200 or so values from the original array and then only selects every 3rd value (or even a logarithmic selection) of the original array to construct the new array. I was thinking about doing this with a loop, but I was wondering if matlab had any built-in functions that could do this.
Thanks, Charles

Accepted Answer

Roger Stafford
Roger Stafford on 23 May 2013
For spacing every third element
p = a:3:b;
For logarithmic spacing
p = round(k*a.^(1:n));
for appropriate a, k, and n. Then do this:
new_array = old_array(p);
  4 Comments
Cedric
Cedric on 23 May 2013
Edited: Cedric on 23 May 2013
What Roger is generating is an array of IDs/positions (that he then uses for indexing operations); you can work with these as you work with any other array; in particular, you can concatenate them, e.g.
p = [1:200, 203:3:1000] ;
or
p = [1:200, 200+3^(1:5)] ;
etc. Experiment with smaller numbers so you can easily visualize p.
Senaasa
Senaasa on 23 May 2013
Ok, I've got it now. Thanks a lot guys

Sign in to comment.

More Answers (0)

Categories

Find more on Matrices and Arrays in Help Center and File Exchange

Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!