MATLAB find first elements in columns of array -

within context of writing function, have following example matrix:

temp =       1     2     0     0     1     0      1     0     0     0     0     0      0     1     0     0     0     1 

i want obtain array each element indicates number of element out of non-zero elements starts column. if column empty, element should correspond next non-empty column. matrix temp, result be:

result = [1 3 5 5 5 6] 

because first non-zero element starts first column, third starts second column, fifth starts fifth column , sixth starts sixth column.

how can operation general matrix (one may or may not contain empty columns) in vectorized way?

code:

temp = [1 2 0 0 1 0; 1 0 0 0 0 0; 0 1 0 0 0 1] t10  = temp~=0 l2 = cumsum(t10(end:-1:1)) temp2 = reshape(l2(end)-l2(end:-1:1)+1, size(temp)) result = temp2(1,:) 

output:

temp =      1     2     0     0     1     0      1     0     0     0     0     0      0     1     0     0     0     1  t10 =      1     1     0     0     1     0      1     0     0     0     0     0      0     1     0     0     0     1  l2 =      1     1     1     1     1     2     2     2     2     2     2     2     3     3     4     4     5     6  temp2 =      1     3     5     5     5     6      2     4     5     5     6     6      3     4     5     5     6     6  result =      1     3     5     5     5     6 

---

printing values of each step may clearer explanation. use cumsum ids of non-zero elements. need know id before reaching element, reversed cumsum do. thing left reverse id numbers back.