# Alternative to while loops without using loop?

조회 수: 9 (최근 30일)
Manne Plok 2018년 9월 5일
편집: the cyclist 2018년 9월 5일
Hi, are there any more efficient alternatives to while loops. eg
a = zeros(3,1,3);
b = ones(3,1,3);
while isequal(a,b) == 0
a(:,:,1) = [round(rand);round(rand);round(rand)];
a(:,:,2) = [round(rand);round(rand);round(rand)];
a(:,:,3) = [round(rand);round(rand);round(rand)];
b(:,:,1) = [round(rand);round(rand);round(rand)];
b(:,:,2) = [round(rand);round(rand);round(rand)];
b(:,:,3) = [round(rand);round(rand);round(rand)];
end
I

댓글을 달려면 로그인하십시오.

### 답변 (2개)

the cyclist 2018년 9월 5일
a = zeros(3,1,3);
b = ones(3,1,3);
while not(isequal(a,b))
a = round(rand(3,1,3));
b = round(rand(3,1,3));
end
##### 댓글 수: 4이전 댓글 2개 표시이전 댓글 2개 숨기기
the cyclist 2018년 9월 5일
Separate non sequitur remark ... if you have the Statistics and Machine Learning Toolbox, you could use the binornd command instead of round(rand()) to generate zeros and ones. I'm not sure which would be more computationally efficient, but I think what you are doing would be clearer.
Steven Lord 2018년 9월 5일
Another alternative would be to use randi specifying [0 1] as the first input.

댓글을 달려면 로그인하십시오.

the cyclist 2018년 9월 5일
편집: the cyclist 2018년 9월 5일
Here is a way to do this without a while loop. It uses the trick I mentioned in a comment, that there are a finite number (512) ways of filling a 3x1x3 array with zeros and ones, and therefore there are 512x511 = 261,632 ways of choosing a pair of distinct entries.
In the code, I ...
• create the full list
• pick a at random
• delete that choice from the list
• pick b at random
list = dec2bin(0:511) - '0';
a_idx = randi(512);
a = reshape(list(a_idx,:),3,1,3);
list(a_idx,:) = [];
b_idx = randi(511);
b = reshape(list(b_idx,:),3,1,3);
The very first line is itself a pretty slick trick for getting all the permutations.

댓글을 달려면 로그인하십시오.

### 카테고리

Help CenterFile Exchange에서 Loops and Conditional Statements에 대해 자세히 알아보기

R2017b

### Community Treasure Hunt

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

Start Hunting!

Translated by