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Preferably using QGis I'd like to remove errors from a road network .shp file and was wondering if there was a away to perform a flood fill or traversal on a vector layer to select all connected vertexes from the starting vertex to do basic validation and remove unconnected roads.


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I'm a bit slow in understanding what you mean. Maybe you can include a picture depicting your question/problem. – Curlew Apr 4 '13 at 10:44

I don't know how to do this in QGIS, but you could use the Sextante-Plugin to do this within GrassGIS.

The command you are searching for is: [-tcr] ainput=name [atype=string[,string,...]] [alayer=integer] binput=name [btype=string[,string,...]] [blayer=integer] output=name [operator=string] [--overwrite] [--verbose] [--quiet] 

A nice tutorial: Combination of areas with areas

... and the grass manual:

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