Please help me in inserting ones in a given matrix in special rows

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MANISH KUMAR
MANISH KUMAR 2016-7-6
评论： Stephen23 2016-7-6
Suppose if I already have a matrix 'X' having only one '1' in few rows and other rows contains zeros only for example matrix given below
X =
[0 0 0 0 1 0 0 0 0 0;
0 1 0 0 0 0 0 0 0 0;
0 0 1 0 0 0 0 0 0 0;
0 0 0 0 0 0 0 0 0 0;
0 0 0 0 0 0 0 0 0 0]
i need a matrix having few (specified number) '1's after existing '1' in each row.
for example output matrix is
Y =
[0 0 0 0 1 1 1 1 0 0;
0 1 1 1 1 1 0 0 0 0;
0 0 1 1 1 0 0 0 0 0;
0 0 0 0 0 0 0 0 0 0;
0 0 0 0 0 0 0 0 0 0]
number of ones to be inserted in specified rows are D = [4; 5; 3; 2; 4];
as in example matrix last two rows are zeros only, there is no need to insert ones in those rows,as there is no '1' appearing in those rows

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回答（2 个）

Stephen23
Stephen23 2016-7-6
编辑：Stephen23 2016-7-6
MATLAB is a high-level language, so there is no need to waste time with ugly loops as if this was some poor low-level language like C++. Vectorized code is much neater:
>> tmp = cumsum(cumsum(X,2),2);
>> Y = bsxfun(@le,tmp,D) & tmp
Y =
0 0 0 0 1 1 1 1 0 0
0 1 1 1 1 1 0 0 0 0
0 0 1 1 1 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
José-Luis
José-Luis 2016-7-6
X = [0 0 0 0 1 0 0 0 0 0;
0 1 0 0 0 0 0 0 0 0;
0 0 1 0 0 0 0 0 0 0;
0 0 0 0 0 0 0 0 0 0;
0 0 0 0 0 0 0 0 0 0]
D = [4; 5; 3; 2; 4];
for row = 1:numel(D)
ic = find(X(row,:));
if ~isempty(ic)
X(row,ic:ic+D-1)= 1;
end
end

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