Hi all,

I’m new with pgrouting/postgresql and I would need some detailed instructions making distance matrix using road network. Can you lead me to a good source or give some instructions here to get started?

Thanks in advance! I have mac and I’d like to use pgrouting via QGIS or grass.

Laura

On 7/24/2013 2:19 PM, Laura Kauria wrote:

Hi all,

I'm new with pgrouting/postgresql and I would need some detailed

instructions making distance matrix using road network. Can you lead me

to a good source or give some instructions here to get started?

Thanks in advance! I have mac and I'd like to use pgrouting via QGIS or

grass.

Hi Laura,

I will outline the process below, but you should read the docs for the details on how to do the steps:

Say you have ten locations the you want to build a distance matrix for:

1. map you locations to the nearest edge nearest end node

2. for each node call pgr_kdijkstra() with the node as source and the remainder of nodes as targets.

3. place the values in real8 array

4. adjust the array to be symmetric ie: a[i,j] == a[j,i] (we only support symmetric TSP

5. call pgr_tsp(a, start_id [, end_id])

I have no idea how you would do this from QGIS or grass.

Hope this helps,

-Steve

Thanks, Steve! I need to start first with something easier, since I see lots of gaps with my skills and this tool(/general pgrouting). I try to figure out it first in grass and if it goes fine, then pgrouting. Cheers, Laura

## ···

2013/7/24 Stephen Woodbridge <woodbri@swoodbridge.com>

On 7/24/2013 2:19 PM, Laura Kauria wrote:

Hi all,

I’m new with pgrouting/postgresql and I would need some detailed

instructions making distance matrix using road network. Can you lead me

to a good source or give some instructions here to get started?

Thanks in advance! I have mac and I’d like to use pgrouting via QGIS or

grass.

Hi Laura,

I will outline the process below, but you should read the docs for the details on how to do the steps:

Say you have ten locations the you want to build a distance matrix for:

- map you locations to the nearest edge nearest end node
- for each node call pgr_kdijkstra() with the node as source and the remainder of nodes as targets.
- place the values in real8 array
- adjust the array to be symmetric ie: a[i,j] == a[j,i] (we only support symmetric TSP
- call pgr_tsp(a, start_id [, end_id])

I have no idea how you would do this from QGIS or grass.

Hope this helps,

-Steve

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