Buffer

En guise d'entrainement, commencez par créer une zone tampon de 5 mètres autour de nos sommets.

import os
import shutil
 
monCheminDeBase = r'C:\\Users\\georg\\Downloads\\'
 
project = QgsProject.instance()
project.removeAllMapLayers()
project.clear()
iface.mapCanvas().refresh()
 
crs = QgsCoordinateReferenceSystem.fromEpsgId(4326)
project.setCrs(crs)
project.setEllipsoid('EPSG:4326')
 
peaks = QgsVectorLayer(monCheminDeBase + 'peaks_selection/peaks_selection.shp', 'Sommets', 'ogr')
QgsProject.instance().addMapLayer(peaks)
 
# Directory for created layer
_peaks_buffer = monCheminDeBase + '_peaks_buffer'
if os.path.isdir(_peaks_buffer) == True:
    shutil.rmtree(_peaks_buffer)
if os.path.isdir(_peaks_buffer) == False:
    os.mkdir(_peaks_buffer)
 
# Buffer on peaks
peaks_buffer_path = _peaks_buffer + r'\\peaks_buffer.shp'
 
processing.run('native:buffer', { \
"INPUT": peaks, \
"DISTANCE": 5, \
"SEGMENTS": 10, \
"END_CAP_STYLE": 0, \
"DISSOLVE": False, \
"OUTPUT": peaks_buffer_path})
 
# Open the buffer layer
peaks_buffer = QgsVectorLayer(peaks_buffer_path, "Buffer area", "ogr")
project.addMapLayer(peaks_buffer)
 
# Register layer
my_buffer = project.mapLayersByName("Buffer area")[0]
 
# Buffer below
root = project.layerTreeRoot()
myBelowLayer = root.findLayer(peaks_buffer.id())
myClone = myBelowLayer.clone()
parent = myBelowLayer.parent()
parent.insertChildNode(-1, myClone)
parent.removeChildNode(myBelowLayer)

Mais le code ci-dessus fonctionne très mal n'est-ce pas ?

• Essayez de tricher
• Essayez de comprendre pourquoi ça ne marche pas
• Inspectez les unités géométriques utilisées dans votre canvas
• Contrôlez vos logs dans View / Panels / Log Messages

Utilisez plutôt le code suivant pour créer des buffer de 2 kms autour de nos 108 000 adresses des Hautes-Alpes.

import os
import shutil
 
monCheminDeBase = r'C:\\Users\\georg\\Downloads\\'
 
project = QgsProject.instance()
project.removeAllMapLayers()
project.clear()
iface.mapCanvas().refresh()
 
crs = QgsCoordinateReferenceSystem.fromEpsgId(2154)
project.setCrs(crs)
project.setEllipsoid('EPSG:2154')
 
address = QgsVectorLayer(monCheminDeBase + 'adresses/ADRESSE_05.shp', 'Adresses', 'ogr')
 
QgsProject.instance().addMapLayer(address)
 
# Directory for created layer
_address_buffer = monCheminDeBase + '_address_buffer'
if os.path.isdir(_address_buffer) == True:
    shutil.rmtree(_address_buffer)
if os.path.isdir(_address_buffer) == False:
    os.mkdir(_address_buffer)
 
# Buffer on address
address_buffer_path = _address_buffer + r'\\address_buffer.shp'
 
processing.run('native:buffer', { \
"INPUT": address, \
"DISTANCE": 2000, \
"SEGMENTS": 10, \
"END_CAP_STYLE": 0, \
"DISSOLVE": False, \
"OUTPUT": address_buffer_path})
 
# Open the buffer layer
address_buffer = QgsVectorLayer(address_buffer_path, "Buffer area", "ogr")
project.addMapLayer(address_buffer)
 
# Register layer
my_buffer = project.mapLayersByName("Buffer area")[0]
 
# Buffer below
root = project.layerTreeRoot()
myBelowLayer = root.findLayer(address_buffer.id())
myClone = myBelowLayer.clone()
parent = myBelowLayer.parent()
parent.insertChildNode(-1, myClone)
parent.removeChildNode(myBelowLayer)

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