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

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

[Cedric]

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

Answer 1

[Andrei Bobrov]

y = [strfind([~X(1) X],[0 1]);strfind([X ~X(end)],[1 0])]';

[Javier]

Thanks Andrei, you are the BEST............

Answer 2

[per isakson]

Try

find( diff( X ) == 1 ) + 1
find( diff( X ) == -1 )

[per isakson]

I've provided more than half of the solution. Your turn.

[Javier]

Thanks per........

Answer 3

[Roger Stafford]

 f = find([false,diff(x)~=0,false]);
 y = [f(1:2:end)',f(2:2:end)'-1];

Answer 4

[Azzi Abdelmalek]

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