How to extract the first and last position for each ones series ?

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Javier
Javier 2013-1-23
For example
How to extract the first and last position for each ones series ?
X= [0 0 1 1 1 0 1 1 0 1 1 1 0 0 1 ]
%result
y =
3 5
7 8
10 12
15 15
Thanks
  1 个评论
Cedric
Cedric 2013-1-23
If it is for indexing something else afterwards, you can use that almost directly for logical indexing; you just have to typecast it to logical. E.g.
>> X = [0 0 1 1 1 0 1 1 0 1 1 1 0 0 1 ] ;
>> a = 1:15 ;
>> a(logical(X))
ans =
3 4 5 7 8 10 11 12 15

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采纳的回答

Andrei Bobrov
Andrei Bobrov 2013-1-23
y = [strfind([~X(1) X],[0 1]);strfind([X ~X(end)],[1 0])]';

更多回答（3 个）

per isakson
per isakson 2013-1-23
Try
find( diff( X ) == 1 ) + 1
find( diff( X ) == -1 )
Roger Stafford
Roger Stafford 2013-1-23
f = find([false,diff(x)~=0,false]);
y = [f(1:2:end)',f(2:2:end)'-1];
Azzi Abdelmalek
Azzi Abdelmalek 2013-1-23
You can use
x= [ 0 0 1 1 1 0 1 1 0 1 1 1 0 0 1 ]
y=[x(1) diff(x)] % to find the first column
x1=fliplr(x) % to find the second column by the first method, just by
% reversing x

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