Counting subrows in each row of a matrix?

Question

MRC 2014-5-7

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/128805-counting-subrows-in-each-row-of-a-matrix

评论： Cedric 2014-5-7

Hi all, I need an algorithm which counts how many adjacent and non-overlapping (1,1) I have in each row of a matrix A mx(n*2) without using loops. E.g.

A=[1 1 1 0 1 1 0 0 0 1; 1 0 1 1 1 1 0 0 1 1] %m=2, n=5

Then I want

B=[2;3] %mx1

In fact A=[(1 1) (1 0) (1 1) (0 0) (0 1); (1 0) (1 1) (1 1) (0 0) (1 1)]. Then, according to this separation, I have 2 (1 1) in the first row and 3 (1 1) in the second row.

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Cedric 2014-5-7

编辑：Cedric 2014-5-7

在 MATLAB Online 中打开

And if one row was

0 1 1 0 0 0

would you count this as

(0 1) (1 0) ..

or still spot the 1 1 block?

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Cedric 2014-5-7

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/128805-counting-subrows-in-each-row-of-a-matrix#answer_135989

编辑：Cedric 2014-5-7

在 MATLAB Online 中打开

Assuming that n is defined previously as

>> n = 5 ;

(for the case of your example) here is a one liner

 >> B = sum( reshape( all( reshape( A.', 2, [] )), n, [] )).'
 B =
     2
     3

2 个评论
显示无隐藏无

MRC 2014-5-7

What if instead (1,1) I want (0,1)?

Cedric 2014-5-7

What is the purpose?

请先登录，再进行评论。

Answer 2

Azzi Abdelmalek 2014-5-7

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/128805-counting-subrows-in-each-row-of-a-matrix#answer_135986

在 MATLAB Online 中打开

I think you need to use at least one loop

A=[1 1 1 0 1 1 0 0 0 1; 1 0 1 1 1 1 0 0 1 1]
for k=1:size(A,1)
  a=[0 A(k,:)  0];
  ii=strfind(a,[1 0])-strfind(a,[0 1]);
  jj=mod(ii,2)~=0;
  ii(jj)=ii(jj)-1;
  out(k)=sum(ii)/2;
end
disp(out)