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Walk on the whole Auckland area.
Can only use pedestrian only ways:
``pgr_extractVertices`` compute the connected components of an undirected graph using a Depth First Search approach. A connected component of an undirected graph is a set of vertices that are all reachable from each other.
`pedestrian`, `steps`, `footway`, `path`, `cycleway`
Description of the function can be found in `pgr_extractVertices <https://docs.pgrouting.org/latest/en/pgr_connectedComponents.html>`__
The walking speed is ``2 mts/sec``.
Configuration from osm2pgrouting
When dealing with data, being aware of what kind of data is being used can improve results.
Vehicles can not circulate on pedestrian ways
Penalizing or removal of pedestrian ways will make the results closer to reality.
When converting data from OSM format using the `osm2pgrouting` tool, there is an additional table: ``configuration``.
The ``configuration`` table structure can be obtained with the following command.
tag_id values
In the image above there is a detail of the ``tag_id`` of the roads.
From the requirements, the graph is going to be based on OSM identifiers.
The `OSM highway <https://wiki.openstreetmap.org/wiki/Key:highway>`__ types:
Also, on the ``ways`` table there is a column that can be used to ``JOIN`` with the ``configuration`` table.
The configuration types in the Auckland data
pgr_extractVertices
``pgr_extractVertices`` extracting the vertex information of the set of edges of a graph.
Update the ``geom`` columns based on the ``source_osm`` column from ``ways`` table.
Signature summary
Description of the function can be found in `pgr_extractVertices <https://docs.pgrouting.org/latest/en/pgr_extractVertices.html>`__
Use the start point of the geometry.
Not expecting to be done due to the fact that some vertices are only dead ends.
Exercise 1: Create a vertices table
Update the ``geom`` columns based on the ``target_osm`` column from ``ways`` table.
Problem
Create the vertices table corresponding to the edges in ``ways``.
Use the end point of the geometry.
Solution
A graph consists of a set of vertices and a set of edges.
In this case, the ``ways`` table is a set of edges.
In order to make use of all the graph functions from pgRouting, it is required have the set of vertices defined.
From the requirements, a fully connected graph is needed, therefore adding a ``component`` column.
Reviewing the description of the vertices table
Inspecting the information on the vertices table
Exercise 2: Fill up other columns in the vertices table
Create additional columns on the edges and vertices tables.
Fill up geometry information on the vertices table.

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  1. pgRouting workshop
  2. basic-graphs
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pgr_extractVertices
pgr_extractVertices
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Source string location
../../build/docs/basic/graphs.rst:126
String age
10 days ago
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10 days ago
Source string age
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Translation file
locale/pot/basic/graphs.pot, string 35