Clear Filters
Clear Filters

Creating a row vector of combinations?

3 views (last 30 days)
I have a row vector that 1 by 4. And I know that the minimum and maximum values of the elements in this vector to be -15 and 15. How can I make a matrix that is N by 4 that contains all possible combinations of ALL values?
Let me given an example: min = -15, max = 15, so the result of the code should be a matrix that is N by 4 that will look something like this
A = [[-15,0,0,0];[-14,0,0,0];[-13,0,0,0];[-12,0,0,0];[-11,0,0,0];[-10,0,0,0];[-9,0,0,0];....and so on until the final value vector to be[15,15,15,15]];

Accepted Answer

Davide Masiello
Davide Masiello on 24 Jan 2023
You could use nchoosek. The example below is from -3 to 3 for memory issues (you'll generate a humongous matrix). Just substitute -15:15 and the trick is done.
A = nchoosek(-3:3,4)
A = 35×4
-3 -2 -1 0 -3 -2 -1 1 -3 -2 -1 2 -3 -2 -1 3 -3 -2 0 1 -3 -2 0 2 -3 -2 0 3 -3 -2 1 2 -3 -2 1 3 -3 -2 2 3
  9 Comments
Dyuman Joshi
Dyuman Joshi on 25 Jan 2023
Nice work, Davide! I sometimes forget that FEx is an amazing resource as well
And the solution checks out, there should be 7^4 rows total for [-3 3]
7^4
ans = 2401
@Ali Almakhmari, you can obtain the desired solution for the intended range, but it would contain
fprintf('%d rows', 31^4)
923521 rows
so it would be difficult to go through all of them.
Ali Almakhmari
Ali Almakhmari on 25 Jan 2023
Thank you all for your help. You have been amazing!

Sign in to comment.

More Answers (1)

Stephen23
Stephen23 on 25 Jan 2023
One simple aprpoach is to download this FEX submission:
but you will need plenty of memory:
V = -3:3
V = 1×7
-3 -2 -1 0 1 2 3
X = combinator(numel(V),4,'p','r');
M = V(X)
M = 2401×4
-3 -3 -3 -3 -3 -3 -3 -2 -3 -3 -3 -1 -3 -3 -3 0 -3 -3 -3 1 -3 -3 -3 2 -3 -3 -3 3 -3 -3 -2 -3 -3 -3 -2 -2 -3 -3 -2 -1
  7 Comments
Stephen23
Stephen23 on 26 Jan 2023
Edited: Stephen23 on 26 Jan 2023
"What do you mean by copy them?"
Perhaps COPYFILE or one of the WEB* or URL* functions lets you copy from the FEX location to the Answers environment, from whence you could run it. Go and read the documentation and do some experiments. I can't help you with this, I have never tried.
"Also, how did you run the function?"
I downloaded it from FEX, uploaded it here, ran the code, then (out of respect for the submitter's license conditions) deleted the function before submitting my answer. You can delete uploaded files by clicking on the little red "x":
Dyuman Joshi
Dyuman Joshi on 27 Jan 2023
Okay, I'll try it. Thanks for replying.
"I downloaded it from FEX, uploaded it here, ran the code, then (out of respect for the submitter's license conditions) deleted the function before submitting my answer."
Fair enough.

Sign in to comment.

Categories

Find more on Resizing and Reshaping Matrices in Help Center and File Exchange

Products


Release

R2021a

Community Treasure Hunt

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

Start Hunting!