How to find set of 3 in a 122x4 matrix?

2 次查看（过去 30 天）
John Hunt
John Hunt 2017-10-13
评论： John Hunt 2017-10-17
I have a matrix that is 122x4. These have index numbers 1-36 with two only rows containing three points that are common between them. How can I find these pairs?
ex
A=[ 1 2 13 15;
1 2 15 35;
1 2 17 22;
1 2 22 36...]
(there is not a pattern throughout the matrix like there are in the first couple rows) I want some thing that can identify the pair of combos
combos = [1 2;
3 4]
where 1,2,3,and 4 are row numbers
If I can also print out the numbers they share that would be great too combos = [1 2 1 2 15;...etc
  7 个评论
显示 5更早的评论
dpb
dpb 2017-10-17
Say what!!!??? I have no klew what the above is intending to say.
Are the three values you're trying to match those in the first three columns only or is it three out of the four in the line that are to be found?
John Hunt
John Hunt 2017-10-17
three out of the four need to match three out of four for the other rows

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Guillaume
Guillaume 2017-10-17
编辑：Guillaume 2017-10-17
This is O(n^2) so is going to be slow for largish matrices. I haven't got the time to think of a cleverer algorithm:
pairs = zeros(0, 5);
for row1 = 1 : size(A, 1)
for row2 = row1+1 : size(A, 1)
commonnumbers = intersect(A(row1, :), A(row2, :));
if numel(commonnumbers ) == 3
pairs = [pairs; row1, row2, commonnumbers]; %#ok<AGROW>
break; %assumes that there is always only one other row that matches
end
end
end
  1 个评论
John Hunt
John Hunt 2017-10-17
Thank you I will go through it to see if I can get it to do what I need

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Logical 的更多信息

标签

Community Treasure Hunt

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

Start Hunting!

Translated by