Counting the number of elements surrounding another element.

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Phillip Smith
Phillip Smith 2019-11-25
编辑： Andrei Bobrov 2019-11-27
Hello,
I've created a matrix and have I randomly set one of these matrix elements equal to 1. Now I want to count how many elements are neighbouring it, I am taking into account diagonal neighbours too i.e. a fully surrounded element will have 8 neighbours etc.
Many thanks,
Phill
  2 个评论
Adam
Adam 2019-11-25
Just determine if it is on an edge (5 neighbours) or a corner (3 neighbours) and if not then as you say, it has 8 neighbours. No need to count them.
Phillip Smith
Phillip Smith 2019-11-25
That works but I want to count the number of 0's around the element (since it's a matrix consisting of only 1's and 0's) and then change one of those 0's into a 1!

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采纳的回答

Turlough Hughes
Turlough Hughes 2019-11-25
If your matrix is called A. You could find the number of 0's surrounding an element at A(m,n) as follows:
D=padarray(A,[1 1],1,'both');
numberzeros=nnz(~D(m:m+2,n:n+2));

更多回答（1 个）

Andrei Bobrov
Andrei Bobrov 2019-11-25
编辑：Andrei Bobrov 2019-11-27
Let x - your array with ones and zeros:
x = double(rand(10) > .45);
out = conv2(double(~x),[1,1,1;1,0,1;1,1,1],'same');

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