[Qgis-developer] calculate distance from two points along line in pyqgis
gene
martin.laloux at gmail.com
Wed Jan 14 01:40:28 PST 2015
I don't have the code posted by Giovanni but this is very easy to do with
Shapely <http://toblerity.org/shapely/manual.html> (a Python wrapper of
GEOS).
With PyQGIS, I do it in this way:
1) by definition a polyline is composed of straight segments between
points (nodes)
2) after computing the intersection between the polylines , the intersecting
point lies on a particular segment, easy to determine.
3) Then a simple loop through the segments (length) allows to compute the
distance between the first point of the line and the intersection point (=
sum of segments length + the length of the segment between the first point
of the segment where the intersecting point lies and the intersection
point).
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