How to obtain next/previous node in a tour represented as an array (=permutation of size n)

I have been struggling to find an efficient solution to my problem. I am working with tours, which basically are permutations of the numbers 1 to n (n is given).

Now I want to code an anonymous function* that would work as follows:

tour = [1 8 9 7 4 5 2 10 6 3];

Next = nextNode(tour,2);
Next2 = nextNode(tour,3);

Prev = prevNode(tour,10);
Prev2 = prevNode(tour,1);

% result should be:
% Next  = 10  
% Next2 = 1
% Prev  = 2  
% Prev2 = 3

Any suggestions and solutions are welcome, thank you!

[madhan ravi]

Birdman why do you keep deleting my answer? You deleted it three times. What's wrong? It's not nice to delete answers.

Answer 1

[madhan ravi]

Note: your prev should be 2 not 6 maybe you made a typo.

tour = [1 8 9 7 4 5 2 10 6 3];
Next = nextNode(tour,2)
Next2 = nextNode(tour,3)
Prev = prevNode(tour,10)
Prev2 = prevNode(tour,1)

function Result = nextNode(tour,n)
idx=find(tour==n);
if idx==numel(tour)
    Result = tour(1);
else
    Result = tour(idx+1);
end
end

function Result1=prevNode(tour,n)
idx=find(tour==n);
if idx==1
    Result1=tour(end);
else
    Result1=tour(idx-1);
end
end

Gives:

Next =

    10

Next2 =

     1

Prev =

     2

Prev2 =

     3

[Berlibur]

Indeed it was a typo. Thanks for helping me out!

[madhan ravi]

My pleasure!