Set logical array values to true if value n values ahead is true

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I'm curious if anyone can find a smart/clean way (other than a for loop of doing the following). Given a logical array x:
x = logical( [0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0] );
For n = 1 I'd like: y = [0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0];
For n = 2 I'd like: y = [0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 0, 0];
etc.
  2 Comments
Matt Fig
Matt Fig on 26 Nov 2012
Edited: Matt Fig on 26 Nov 2012
Your examples conflict with your description. Do you want to place n values in the array ahead of a 1 as your examples show, or do you want to place a single 1 ahead of n 1s, as the title implies? If the latter, do you need to place a 1 only in front of exactly n 1s, or at least n 1s?
Chris
Chris on 27 Nov 2012
Sorry, it is indeed the latter. I want to place n values in the array ahead of a 1. Either exactly or at least are fine b/c x will always have "isolated" 1s.

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Accepted Answer

Andrei Bobrov
Andrei Bobrov on 26 Nov 2012
x = [0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0] > 0;
n = 2;
x(bsxfun(@minus,find(x),(n:-1:1)')) = true;

More Answers (2)

Matt J
Matt J on 26 Nov 2012
n=2;
y=regexprep(char(x+'0'),[repmat('.',1,n),'1'], [repmat('1',1,n),'1'])-'0'

Matt J
Matt J on 26 Nov 2012
y=logical(tril(triu(ones(length(x))),n)*x(:)).'

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