比较矩阵每一行中的元素并计算相似值

Question

I have a matrix like this:

 line=[1 3 5 0 0 4 2; 
       1 3 8 0 8 2 2 ] 

I want to compare the rows in this matrix. If the 1st column of the first row is the same as 1st column of second row then increase a counter. But if the value is zero, then the counter should not be increased.

For the example above I expect the output to be match = 3 where the matching values are 1,3,2 so the match = 3

Answer 1

I would go for this:

match = sum((line(1, :) == line(2, :)) & (line(1, :) != 0))

The Array comparison line(1, :) == line(2, :) will give you (logical) 1 at the points, where both rows have identical values:

ans =
  1  1  0  1  0  0  1

Next, you need to exclude possible 0 values. That can be done by findind non-zero elements just in the first row ( line(1, :) != 0 ), and then using the & operator on the results. You'll get:

ans =
  1  1  0  0  0  0  1

At last, you just have to count the ones using sum .

Answer 2

You can check if the sum of each column divided by the first line equal 2.

So:

count = sum(sum(x)./x(1,:)==2)

Since 0/0 is indetermined, 0 will not be taken into account.