Delete last n1,n2,n3 (...) elements in each row in a Matrix in an efficient way or set to zero

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Tim
Tim 2014-2-21
回答： Roger Stafford 2014-2-22
I've a large set of data and i want to remove from the end of each row a different amount of elements (0-n). Is there a fast way to do this without using a loop?
As an example: A= % In reality different numbers, not only ones!
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
Then I've a vector saying how many elements to delete from each row, e.g.:
B =
1 3 0 2 1
So the result would look like:
A2
1 1 1 1 0
1 1 0 0 0
1 1 1 1 1
1 1 1 0 0
1 1 1 1 0
Thanks so much in advance!

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采纳的回答

Roger Stafford
Roger Stafford 2014-2-22
[m,n] = size(A);
p = cumsum(accumarray([(1:m)',n+1-B'],1,[m,n+1]),2);
A(p(:,1:n)==1) = 0;

更多回答（1 个）

Image Analyst
Image Analyst 2014-2-21
As long as you want to simply set to zero, no need to use cell arrays:
A=[...
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1]
B =[1 3 0 2 1];
for row = 1 : size(A, 2)
A(row,(end-B(row)+1):end) = 0;
end
A % Print to command window.

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