[pgrouting-dev] Problems with TSP

[Stephen Woodbridge]

On 6/23/2013 5:19 AM, Dave Potts wrote:
> Just looked at the write up for the tsp, ok the answer will be in the
> range 0-(X-1) where X is the number of points provided, the returned
> index starts of at zero in set as one as found in postgres arrays.  But
> I do not understand the remark id, 'index into the matrix'  the matrix
> is a two dimension so I I don't understand how the index is desgined to
> work!

Since the the matrix is symmetric NxN, index refers to a row or column, 
so the resultant path would be for you first example below would be:

0,2: 20
1,3:  2
2,1: 90
3,0: 42

or a path from 2 -> 3 -> 1 -> 0 for a cost of (20+2+90+42) = 154

> On 23/06/13 10:04, Dave Potts wrote:
>> I having some problems with the tsp
>>
>> I have a matrix {{0,31,22,42},{31,0,90,2},{22,90,0,27},{42,2,27,0}},
>> starting at node 2,  I get the answer
>> seq | id
>> -----+----
>>    0 |  2
>>    1 |  3
>>    2 |  1
>>    3 |  0
>> (4 rows)
>> using the matrix

So as you figured out, 4 is invalid, and probably should throw an error 
(write a ticket for this) as the nodes are 0-3.

-Steve

>>  {{0,22,42,31},{22,0,27,90},{42,27,0,2},{31,90,2,0}} starting at node
>> 4  I get the answer
>> seq | id
>> -----+----
>>    0 |  0
>>    1 |  1
>>    2 |  2
>>    3 |  3
>> The matrix is topological identicial, I start off at the same
>> topological node, so I was expecting the same answer, also I was
>> expecting all nodes to be in the result set ie nodes 1,2,3 and 4, for
>> some strange reason I get 0.
>>
>> Is there some mistake in my data?
>>
>> regards
>>
>>
>> Dave.
>>
>>
>>
>>
>>
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>
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