How to add an existing QGSVectorLayer to QGIS project?

Question

I know I can pull a vector file into my current project using:

vlayer = iface.addVectorLayer(r"S:/Data/Natural_Earth_quick_start/110m_cultural/ne_110m_admin_0_countries.shp", "admin", "ogr")

But if I create my layer using something like:

vlayer = QgsVectorLayer(r"S:/Data/Natural_Earth_quick_start/110m_cultural/ne_110m_admin_0_countries.shp", "admin", "ogr")

and then I do some processing on vlayer how do I then add it to the current project or map layers list?

Answer 1

• To add an existing single layer:

  vlayer = QgsVectorLayer("some/path/to/shapefile.shp", "admin", "ogr")
  QgsProject.instance().addMapLayer(vlayer)
  

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• To add existing multiple layers:

  vlayer1 = QgsVectorLayer("some/path/to/shapefile1.shp", "admin1", "ogr")
  vlayer2 = QgsVectorLayer("some/path/to/shapefile2.shp", "admin2", "ogr")
  layers = [vlayer1 , vlayer2]
  QgsProject.instance().addMapLayers(layers)