nodesogrqgis
I have a line Shapefile that I need to remove many nodes from.
Some I can delete fine, others delete but when I hit save I receive the following error:
OGR error creating geometry for feature
Using QGIS version 2.14.0-Essen in Win10 64 bit.
Any ideas? I've converted it to multipoint then back to single point with no change.
In a command window, type set > set.txt to get a list of all environment variables you have set. Your python installation may have set some values that QGIS does not like.
The PATH variable is save, because qgis.bat sets its own path variable, but PYTHONPATH or something else may be harmful.
Once you found a link to C:\Python27, go to the system properties and change the environment variable (not sure how the commands are in your language version).
What is strange if the intersection result is a point ?
The intersect predicate is
Returns True if the boundary and interior of the object intersect in any way with those of the other.
With a common point between the geometries, the intersects predicate returns TRUE because the boundary of the first geometry intersects the boundary of the second geometry at this point. The result is always this point
from shapely.geometry import LineString, Polygon
from shapely.wkt import loads
Line1 = loads("LINESTRING ({0} {0}, {1} {0})".format(0, 1))
Line2 = loads("LINESTRING ({1} {0}, {2} {0})".format(0, 1, 2))
Line1.intersects(Line2)
True
Line1.touches(Line2)
True
Line1.intersection(Line2).wkt
'POINT (1 0)'
# polygons
polygon1 = loads('POLYGON (( 140 360, 140 480, 220 480, 220 360, 140 360 ))')
polygon2 = loads('POLYGON (( 220 260, 220 360, 300 360, 300 260, 220 260 ))')
polygon1.intersection(polygon2).wkt
'POINT (220 360)'
In your case the resulting layer is an ogr.wkbPoint
If you change the value of the point, the result is
polygon3 = loads('POLYGON (( 220 260, 220 370, 300 360, 300 260, 220 260 ))')
polygon1.intersection(polygon3).wkt
'LINESTRING (220 370, 220 360)'
Or
polygon4 = loads('POLYGON ((220 260, 200 370, 300 360, 300 260, 220 260))')
polygon1.intersection(polygon4).wkt
'POLYGON ((220 368, 220 360, 201.8181818181818 360, 200 370, 220 368))'
UPDATE 2: With Shapely, there is no problem to clip a roads Shapefile using a polygon even if the road vertex points and the edge of the polygon coincide
roads = loads('LineString (220 360, 120 468)')
polygon1.intersection(roads).wkt
'LINESTRING (220 360, 140 446.4)'
Best Answer
Try selecting the feature and then deleting it after selection:
If you are trying to delete an entire feature by deleting nodes or "deleting part of feature", this usually generates an error (from my experience).