MATLAB: Negative continuous position on vector

findlengthMATLABunique

Hi I have a question, i know how to solve with the code I show in the bottom of the page but i think that it has to be an easyer way. What I want to do is: starting with a vector row AA containing only one one in one position, for example:

AA = [0 0 1 0 0 0 0];

I want to get a BB vector that's next:

BB = [-2 -1 0 1 2 3 4];

A vector in which the numbers to the left of 1 are negative crescent in which the first component is the most negative position possible, the point 1 becomes 0 and the right of 1 is positive crescent until the end of the vector.

The code I know how to do is this:

AA = [0 0 1 0 0 0 0]
[m,n] = size(AA);
x = find(AA(1,:),1)
neg = AA(1:x-1)
BB(1,x) = 0
BB(1,1:length(neg)) = -length(neg):1:-1
BB(1,x+1:n) = 1:1:n-x

But I don't see that this is a very good way to get the solution…

Best Answer

BB = (1:length(AA))-find(AA==1,1)

Related Solutions

MATLAB: Complete cell positions with NaN

AA{1,1} = [0 0 1 0 0 0 0];
AA{2,1} = [0 1 0 0];
AA{3,1} = [0 0 0 1 0 0 0 0 0];
i1=cellfun(@(a) find(a==1,1), AA);
maxi1=max(i1);
lgt=cellfun(@length,AA);
idx = arrayfun(@(lgt,i1) (1:lgt)-i1, lgt, i1, 'unif', 0);
col = cellfun(@(idx) idx+maxi1, idx, 'UniformOutput', false);
row = arrayfun(@(r) r+zeros(size(idx{r})), 1:size(idx,1), 'UniformOutput', false);
COL=[col{:}];
ROW=[row{:}];
IDX=[idx{:}];
BB = accumarray([ROW(:) COL(:)],IDX(:),[],[],NaN);
CC=num2cell(BB,2);
CC{:}

MATLAB: How to create a structuring element of the own

Elements outside the boundary of the matrix do not participate in the erosion/dilation. If you pad aa to a larger size, you will see different effects.

>> aaa=zeros(5); aaa(2:4,2:4)=aa
aaa =
       0     0     0     0     0
       0     1     1     1     0
       0     1     0     1     0
       0     1     1     1     0
       0     0     0     0     0
>> ero=imerode(aaa,[1,1,1])
ero =
       0     0     0     0     0
       0     0     1     0     0
       0     0     0     0     0
       0     0     1     0     0
       0     0     0     0     0
>> ero=imerode(aaa,[1,0,1])
ero =
       0     0     0     0     0
       1     0     1     0     1
       1     0     1     0     1
       1     0     1     0     1
       0     0     0     0     0
>> ero=imdilate(aaa,[1,0,1])
ero =
       0     0     0     0     0
       1     1     1     1     1
       1     0     1     0     1
       1     1     1     1     1
       0     0     0     0     0

Related Question