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Dijkstra Algorithm

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Dijstra algorithm to solve shortest path problem.

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This algorithm is to solve shortest path problem.

Usage
[cost rute] = dijkstra(graph, source, destination)

note : graph is matrix that represent the value of the edge. if node not connected with other node, value of the edge is 0.

example:
Finding shortest path form node 1 to node 7.

>> G = [0 3 9 0 0 0 0;
0 0 0 7 1 0 0;
0 2 0 7 0 0 0;
0 0 0 0 0 2 8;
0 0 4 5 0 9 0;
0 0 0 0 0 0 4;
0 0 0 0 0 0 0;
];
>> [cost rute] = dijkstra(G,1,7)

it will resulting

cost = 15
rute = [7 6 4 5 2 1]

Rofi SR

aqsa khan

aqsa khan (view profile)

Hi,
I am currently using this code in my research and it works perfectly fine for the small matrix but when i used this code to find the shortest path in large network which contains 3-4 lac nodes, Matlab gives me error of out of memory to create such a big matrix G. Please help me if you have any solution to this problem. Thanks

GIST

GIST (view profile)

Albert Carfax --> Thank you!!

GIST

Kristian Takac

Kristian Takac (view profile)

Hi,
Could you please tell me if it is possible to rewrite this algorithm to a form which will work with negative, respectively non-positive paths as well?

Thank you!

Miguel Ruiz

Miguel Ruiz (view profile)

If dijkstra(G,1,2) = 3, how come dijkstra(G,2,1) = inf ?

Claire Wong

Claire Wong (view profile)

why it cannot define the A.
>> dijkstra(A, s, d)
Undefined function or variable 'A'.

Albert Carfax

Albert Carfax (view profile)

I found the error. To summarize what I've read of previous comments and confirmed myself, the code returns an incorrect route whenever the path passes through node one. This is because the code reorders the graph so that the source is node 1 and what was previously node 1 is now given the index that the source had previously (line 31: A=exchangenode(A,1,s);). When outputting the route, however, the indecies are not switched back properly. The index of the source is switched back (line 6 of linedijkstra: L=[L s];), but not the node was in the node 1 slot and got bumped out. Thus the route, if it passes through the original node one, will look like it passes through the source node and then still ends up at the source node.

You can fix the problem by either always arranging your graph so that the the source is node 1 or make the following substitution in listdijkstra.m:

Old code:

L=[L W(index2,1)];

New code:

if W(index2,1)==s
L = [L 1];
else
L=[L W(index2,1)];
end

flyingpig

Khang Nguyen

Khang Nguyen (view profile)

In listdijkstra, line 6, instead of having L=[L s], replace it with L=[s L]. That should solve the problem.

MoysesDutra

MoysesDutra (view profile)

This code have one problem when route pass on first node (node number 1)
I'm Still looking for this mistake on code to correct it.

MoysesDutra

MoysesDutra (view profile)

Very good.
Works perfectly in our problem.
Thanks a lot.

David Molony

hanyu li

useful

Nikos Bousios

Palmer Anisi

Palmer Anisi (view profile)

There is a bug in this code. Node 1 is usually replaced by node 4 for paths containing node 1

Falk Lieder

Harry

Shunbo Lei

Shunbo Lei (view profile)

I recently find a bug of this code. If the path contain node 1, it generally will be replaced by the source node number.

aqeel lami

aqeel lami

aqeel lami (view profile)

it works great and thanks

Ronan

Ronan (view profile)

Could you please explain how you are defining nodes. It is not clear at all what how the source node and destination node are chosen and how the route relates to the start and end node?

Sara Baldwin

Sara Baldwin (view profile)

Hello I tried using this function but I am having trouble....In my matrix I have whole numbers but the matrix is a double (not sure why) and this algorithm is not working :(

Paul yang

Paul yang (view profile)

it works great! is there a version that provides all paths, rather than just the shortest path?

Martin

Martin (view profile)

does anyone have the comments for this code. It works perfectly but i would like to understand the role of each function

Cosy

Cosy (view profile)

Hi there,

what is wrong with this example:

G = [ 0 1 2;
1 0 0;
2 0 0 ]

dijkstra(G,2,3);

result: [3 2 2]

Can you help me?

PS: I see that Gautam Marwaha had the same problem. :(

Gautam Marwaha

Gautam Marwaha (view profile)

This code mostly works fine but fails for a few cases:
G = [0 1 1 1 1 0 0;
1 0 0 1 0 1 0;
1 0 0 1 0 1 1;
1 1 1 0 1 0 0;
1 0 0 1 0 0 1;
0 1 1 0 0 0 1;
0 0 1 0 1 1 0];

dijkstra(G,3,5) yields [5 3 3] or [3 3 5]. Any ideas why this happens?

Alex George

Alex George (view profile)

any idea on how this works?

taewoo

!!

Poonam

good algo..

Matthias

Matthias (view profile)

It worked for my purpose! Thanks for it. 4 of 5 because i haven't tested it in extreme situations. Very well!!!

MATLAB Release
MATLAB 7.0.1 (R14SP1)