Skip to main content
Geographic Information Systems

Return to Answer

Rollback to Revision 3 - Edit approval overridden by post owner or moderator
Source Link
gene
gene
  • 55.4k
  • 3
  • 113
  • 191

it is not realy complicated, look at Memory provider in vector: :

  • a point is created with QgsPoint(x,y) and QgsGeometry.fromPoint(QgsPoint(x,y))
  • a line is created with two points: QgsGeometry.fromPolyline([QgsPoint(x1,y1),QgsPoint(x2,y2)]))
  • a polygon is created with a list of points: QgsGeometry.fromPolygon([[QgsPoint(x1,y1),QgsPoint(x2,y2), QgsPoint(x3,y3)]])

  1. two points:

    create a memory layer with two points

    layer = QgsVectorLayer('Point', 'points' , "memory") pr = layer.dataProvider()

    add the first point

    pt = QgsFeature() point1 = QgsPoint(50,50) pt.setGeometry(QgsGeometry.fromPoint(point1)) pr.addFeatures([pt])

    update extent of the layer

    layer.updateExtents()

    add the second point

    pt = QgsFeature() point2 = QgsPoint(100,150) pt.setGeometry(QgsGeometry.fromPoint(point2)) pr.addFeatures([pt])

    update extent

    layer.updateExtents()

    add the layer to the canvas

    QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. the line connecting the two points

    layer = QgsVectorLayer('LineString', 'line' , "memory") pr = layer.dataProvider() line = QgsFeature() line.setGeometry(QgsGeometry.fromPolyline([point1,point2])) pr.addFeatures([line]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. a polygon covering the points

    layer = QgsVectorLayer('Polygon', 'poly' , "memory") pr = layer.dataProvider() poly = QgsFeature() points = [point1,QgsPoint(50,150),point2,QgsPoint(100,50)]

    or points = [QgsPoint(50,50),QgsPoint(50,150),QgsPoint(100,150),QgsPoint(100,50)]

    poly.setGeometry(QgsGeometry.fromPolygon([points])) pr.addFeatures([poly]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

-

Changes in QGIS 3.0 and onward:

For QGIS 3.0 and onward the above workflow is still correct, but certain functions have changed. See https://qgis.org/api/api_break.html

To update the above code, change following functions:

QgsPoint -> QgsPointXY
QgsGeometry.fromPointQgsfromPoint -> QgsGeometry.fromPointXYQgsfromPointXY
QgsGeometry.fromPolylineQgsfromPolyline -> QgsGeometry.fromPolylineXYQgsfromPolylineXY
QgsGeometry.fromPolygonQgsfromPolygon -> QgsGeometry.fromPolygonXYQgsfromPolylineXY
QgsfromPolyline -> QgsfromPolylineXY
QgsMapLayerRegistry -> QgsProject

it is not realy complicated, look at Memory provider in vector: :

  • a point is created with QgsPoint(x,y) and QgsGeometry.fromPoint(QgsPoint(x,y))
  • a line is created with two points: QgsGeometry.fromPolyline([QgsPoint(x1,y1),QgsPoint(x2,y2)]))
  • a polygon is created with a list of points: QgsGeometry.fromPolygon([[QgsPoint(x1,y1),QgsPoint(x2,y2), QgsPoint(x3,y3)]])

  1. two points:

    create a memory layer with two points

    layer = QgsVectorLayer('Point', 'points' , "memory") pr = layer.dataProvider()

    add the first point

    pt = QgsFeature() point1 = QgsPoint(50,50) pt.setGeometry(QgsGeometry.fromPoint(point1)) pr.addFeatures([pt])

    update extent of the layer

    layer.updateExtents()

    add the second point

    pt = QgsFeature() point2 = QgsPoint(100,150) pt.setGeometry(QgsGeometry.fromPoint(point2)) pr.addFeatures([pt])

    update extent

    layer.updateExtents()

    add the layer to the canvas

    QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. the line connecting the two points

    layer = QgsVectorLayer('LineString', 'line' , "memory") pr = layer.dataProvider() line = QgsFeature() line.setGeometry(QgsGeometry.fromPolyline([point1,point2])) pr.addFeatures([line]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. a polygon covering the points

    layer = QgsVectorLayer('Polygon', 'poly' , "memory") pr = layer.dataProvider() poly = QgsFeature() points = [point1,QgsPoint(50,150),point2,QgsPoint(100,50)]

    or points = [QgsPoint(50,50),QgsPoint(50,150),QgsPoint(100,150),QgsPoint(100,50)]

    poly.setGeometry(QgsGeometry.fromPolygon([points])) pr.addFeatures([poly]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

-

Changes in QGIS 3.0 and onward:

For QGIS 3.0 and onward the above workflow is still correct, but certain functions have changed. See https://qgis.org/api/api_break.html

To update the above code, change following functions:

QgsPoint -> QgsPointXY
QgsGeometry.fromPoint -> QgsGeometry.fromPointXY
QgsGeometry.fromPolyline -> QgsGeometry.fromPolylineXY
QgsGeometry.fromPolygon -> QgsGeometry.fromPolygonXY
QgsMapLayerRegistry -> QgsProject

it is not realy complicated, look at Memory provider in vector: :

  • a point is created with QgsPoint(x,y) and QgsGeometry.fromPoint(QgsPoint(x,y))
  • a line is created with two points: QgsGeometry.fromPolyline([QgsPoint(x1,y1),QgsPoint(x2,y2)]))
  • a polygon is created with a list of points: QgsGeometry.fromPolygon([[QgsPoint(x1,y1),QgsPoint(x2,y2), QgsPoint(x3,y3)]])

  1. two points:

    create a memory layer with two points

    layer = QgsVectorLayer('Point', 'points' , "memory") pr = layer.dataProvider()

    add the first point

    pt = QgsFeature() point1 = QgsPoint(50,50) pt.setGeometry(QgsGeometry.fromPoint(point1)) pr.addFeatures([pt])

    update extent of the layer

    layer.updateExtents()

    add the second point

    pt = QgsFeature() point2 = QgsPoint(100,150) pt.setGeometry(QgsGeometry.fromPoint(point2)) pr.addFeatures([pt])

    update extent

    layer.updateExtents()

    add the layer to the canvas

    QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. the line connecting the two points

    layer = QgsVectorLayer('LineString', 'line' , "memory") pr = layer.dataProvider() line = QgsFeature() line.setGeometry(QgsGeometry.fromPolyline([point1,point2])) pr.addFeatures([line]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. a polygon covering the points

    layer = QgsVectorLayer('Polygon', 'poly' , "memory") pr = layer.dataProvider() poly = QgsFeature() points = [point1,QgsPoint(50,150),point2,QgsPoint(100,50)]

    or points = [QgsPoint(50,50),QgsPoint(50,150),QgsPoint(100,150),QgsPoint(100,50)]

    poly.setGeometry(QgsGeometry.fromPolygon([points])) pr.addFeatures([poly]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

-

Changes in QGIS 3.0 and onward:

For QGIS 3.0 and onward the above workflow is still correct, but certain functions have changed. See https://qgis.org/api/api_break.html

To update the above code, change following functions:

QgsPoint -> QgsPointXY
QgsfromPoint -> QgsfromPointXY
QgsfromPolyline -> QgsfromPolylineXY
QgsfromPolygon -> QgsfromPolylineXY
QgsfromPolyline -> QgsfromPolylineXY
QgsMapLayerRegistry -> QgsProject
corrected the function name "QgsGeometry.fromPolygonXY"
Source Link
edit approved May 18, 2019 at 15:22
Youssef
edit approved May 18, 2019 at 15:22
Youssef
  • 385
  • 1
  • 2
  • 10

it is not realy complicated, look at Memory provider in vector: :

  • a point is created with QgsPoint(x,y) and QgsGeometry.fromPoint(QgsPoint(x,y))
  • a line is created with two points: QgsGeometry.fromPolyline([QgsPoint(x1,y1),QgsPoint(x2,y2)]))
  • a polygon is created with a list of points: QgsGeometry.fromPolygon([[QgsPoint(x1,y1),QgsPoint(x2,y2), QgsPoint(x3,y3)]])

  1. two points:

    create a memory layer with two points

    layer = QgsVectorLayer('Point', 'points' , "memory") pr = layer.dataProvider()

    add the first point

    pt = QgsFeature() point1 = QgsPoint(50,50) pt.setGeometry(QgsGeometry.fromPoint(point1)) pr.addFeatures([pt])

    update extent of the layer

    layer.updateExtents()

    add the second point

    pt = QgsFeature() point2 = QgsPoint(100,150) pt.setGeometry(QgsGeometry.fromPoint(point2)) pr.addFeatures([pt])

    update extent

    layer.updateExtents()

    add the layer to the canvas

    QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. the line connecting the two points

    layer = QgsVectorLayer('LineString', 'line' , "memory") pr = layer.dataProvider() line = QgsFeature() line.setGeometry(QgsGeometry.fromPolyline([point1,point2])) pr.addFeatures([line]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. a polygon covering the points

    layer = QgsVectorLayer('Polygon', 'poly' , "memory") pr = layer.dataProvider() poly = QgsFeature() points = [point1,QgsPoint(50,150),point2,QgsPoint(100,50)]

    or points = [QgsPoint(50,50),QgsPoint(50,150),QgsPoint(100,150),QgsPoint(100,50)]

    poly.setGeometry(QgsGeometry.fromPolygon([points])) pr.addFeatures([poly]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

-

Changes in QGIS 3.0 and onward:

For QGIS 3.0 and onward the above workflow is still correct, but certain functions have changed. See https://qgis.org/api/api_break.html

To update the above code, change following functions:

QgsPoint -> QgsPointXY
QgsfromPoint -> QgsfromPointXY
QgsfromPolylineQgsGeometry.fromPoint -> QgsfromPolylineXYQgsGeometry.fromPointXY
QgsfromPolygonQgsGeometry.fromPolyline -> QgsfromPolylineXYQgsGeometry.fromPolylineXY
QgsfromPolylineQgsGeometry.fromPolygon -> QgsfromPolylineXYQgsGeometry.fromPolygonXY
QgsMapLayerRegistry -> QgsProject

it is not realy complicated, look at Memory provider in vector: :

  • a point is created with QgsPoint(x,y) and QgsGeometry.fromPoint(QgsPoint(x,y))
  • a line is created with two points: QgsGeometry.fromPolyline([QgsPoint(x1,y1),QgsPoint(x2,y2)]))
  • a polygon is created with a list of points: QgsGeometry.fromPolygon([[QgsPoint(x1,y1),QgsPoint(x2,y2), QgsPoint(x3,y3)]])

  1. two points:

    create a memory layer with two points

    layer = QgsVectorLayer('Point', 'points' , "memory") pr = layer.dataProvider()

    add the first point

    pt = QgsFeature() point1 = QgsPoint(50,50) pt.setGeometry(QgsGeometry.fromPoint(point1)) pr.addFeatures([pt])

    update extent of the layer

    layer.updateExtents()

    add the second point

    pt = QgsFeature() point2 = QgsPoint(100,150) pt.setGeometry(QgsGeometry.fromPoint(point2)) pr.addFeatures([pt])

    update extent

    layer.updateExtents()

    add the layer to the canvas

    QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. the line connecting the two points

    layer = QgsVectorLayer('LineString', 'line' , "memory") pr = layer.dataProvider() line = QgsFeature() line.setGeometry(QgsGeometry.fromPolyline([point1,point2])) pr.addFeatures([line]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. a polygon covering the points

    layer = QgsVectorLayer('Polygon', 'poly' , "memory") pr = layer.dataProvider() poly = QgsFeature() points = [point1,QgsPoint(50,150),point2,QgsPoint(100,50)]

    or points = [QgsPoint(50,50),QgsPoint(50,150),QgsPoint(100,150),QgsPoint(100,50)]

    poly.setGeometry(QgsGeometry.fromPolygon([points])) pr.addFeatures([poly]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

-

Changes in QGIS 3.0 and onward:

For QGIS 3.0 and onward the above workflow is still correct, but certain functions have changed. See https://qgis.org/api/api_break.html

To update the above code, change following functions:

QgsPoint -> QgsPointXY
QgsfromPoint -> QgsfromPointXY
QgsfromPolyline -> QgsfromPolylineXY
QgsfromPolygon -> QgsfromPolylineXY
QgsfromPolyline -> QgsfromPolylineXY
QgsMapLayerRegistry -> QgsProject

it is not realy complicated, look at Memory provider in vector: :

  • a point is created with QgsPoint(x,y) and QgsGeometry.fromPoint(QgsPoint(x,y))
  • a line is created with two points: QgsGeometry.fromPolyline([QgsPoint(x1,y1),QgsPoint(x2,y2)]))
  • a polygon is created with a list of points: QgsGeometry.fromPolygon([[QgsPoint(x1,y1),QgsPoint(x2,y2), QgsPoint(x3,y3)]])

  1. two points:

    create a memory layer with two points

    layer = QgsVectorLayer('Point', 'points' , "memory") pr = layer.dataProvider()

    add the first point

    pt = QgsFeature() point1 = QgsPoint(50,50) pt.setGeometry(QgsGeometry.fromPoint(point1)) pr.addFeatures([pt])

    update extent of the layer

    layer.updateExtents()

    add the second point

    pt = QgsFeature() point2 = QgsPoint(100,150) pt.setGeometry(QgsGeometry.fromPoint(point2)) pr.addFeatures([pt])

    update extent

    layer.updateExtents()

    add the layer to the canvas

    QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. the line connecting the two points

    layer = QgsVectorLayer('LineString', 'line' , "memory") pr = layer.dataProvider() line = QgsFeature() line.setGeometry(QgsGeometry.fromPolyline([point1,point2])) pr.addFeatures([line]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. a polygon covering the points

    layer = QgsVectorLayer('Polygon', 'poly' , "memory") pr = layer.dataProvider() poly = QgsFeature() points = [point1,QgsPoint(50,150),point2,QgsPoint(100,50)]

    or points = [QgsPoint(50,50),QgsPoint(50,150),QgsPoint(100,150),QgsPoint(100,50)]

    poly.setGeometry(QgsGeometry.fromPolygon([points])) pr.addFeatures([poly]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

-

Changes in QGIS 3.0 and onward:

For QGIS 3.0 and onward the above workflow is still correct, but certain functions have changed. See https://qgis.org/api/api_break.html

To update the above code, change following functions:

QgsPoint -> QgsPointXY
QgsGeometry.fromPoint -> QgsGeometry.fromPointXY
QgsGeometry.fromPolyline -> QgsGeometry.fromPolylineXY
QgsGeometry.fromPolygon -> QgsGeometry.fromPolygonXY
QgsMapLayerRegistry -> QgsProject
Updated for QGIS 3.0 and onward
Source Link
edit approved Jan 27, 2019 at 21:05
Community Bot
edit approved Jan 27, 2019 at 21:05
Community Bot
  • 1

it is not realy complicated, look at Memory provider in vector: :

  • a point is created with QgsPoint(x,y) and QgsGeometry.fromPoint(QgsPoint(x,y))
  • a line is created with two points: QgsGeometry.fromPolyline([QgsPoint(x1,y1),QgsPoint(x2,y2)]))
  • a polygon is created with a list of points: QgsGeometry.fromPolygon([[QgsPoint(x1,y1),QgsPoint(x2,y2), QgsPoint(x3,y3)]])

  1. two points:

    create a memory layer with two points

    layer = QgsVectorLayer('Point', 'points' , "memory") pr = layer.dataProvider()

    add the first point

    pt = QgsFeature() point1 = QgsPoint(50,50) pt.setGeometry(QgsGeometry.fromPoint(point1)) pr.addFeatures([pt])

    update extent of the layer

    layer.updateExtents()

    add the second point

    pt = QgsFeature() point2 = QgsPoint(100,150) pt.setGeometry(QgsGeometry.fromPoint(point2)) pr.addFeatures([pt])

    update extent

    layer.updateExtents()

    add the layer to the canvas

    QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. the line connecting the two points

    layer = QgsVectorLayer('LineString', 'line' , "memory") pr = layer.dataProvider() line = QgsFeature() line.setGeometry(QgsGeometry.fromPolyline([point1,point2])) pr.addFeatures([line]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. a polygon covering the points

    layer = QgsVectorLayer('Polygon', 'poly' , "memory") pr = layer.dataProvider() poly = QgsFeature() points = [point1,QgsPoint(50,150),point2,QgsPoint(100,50)]

    or points = [QgsPoint(50,50),QgsPoint(50,150),QgsPoint(100,150),QgsPoint(100,50)]

    poly.setGeometry(QgsGeometry.fromPolygon([points])) pr.addFeatures([poly]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

-

Changes in QGIS 3.0 and onward:

For QGIS 3.0 and onward the above workflow is still correct, but certain functions have changed. See https://qgis.org/api/api_break.html

To update the above code, change following functions:

QgsPoint -> QgsPointXY
QgsfromPoint -> QgsfromPointXY
QgsfromPolyline -> QgsfromPolylineXY
QgsfromPolygon -> QgsfromPolylineXY
QgsfromPolyline -> QgsfromPolylineXY
QgsMapLayerRegistry -> QgsProject

it is not realy complicated, look at Memory provider in vector: :

  • a point is created with QgsPoint(x,y) and QgsGeometry.fromPoint(QgsPoint(x,y))
  • a line is created with two points: QgsGeometry.fromPolyline([QgsPoint(x1,y1),QgsPoint(x2,y2)]))
  • a polygon is created with a list of points: QgsGeometry.fromPolygon([[QgsPoint(x1,y1),QgsPoint(x2,y2), QgsPoint(x3,y3)]])

  1. two points:

    create a memory layer with two points

    layer = QgsVectorLayer('Point', 'points' , "memory") pr = layer.dataProvider()

    add the first point

    pt = QgsFeature() point1 = QgsPoint(50,50) pt.setGeometry(QgsGeometry.fromPoint(point1)) pr.addFeatures([pt])

    update extent of the layer

    layer.updateExtents()

    add the second point

    pt = QgsFeature() point2 = QgsPoint(100,150) pt.setGeometry(QgsGeometry.fromPoint(point2)) pr.addFeatures([pt])

    update extent

    layer.updateExtents()

    add the layer to the canvas

    QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. the line connecting the two points

    layer = QgsVectorLayer('LineString', 'line' , "memory") pr = layer.dataProvider() line = QgsFeature() line.setGeometry(QgsGeometry.fromPolyline([point1,point2])) pr.addFeatures([line]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. a polygon covering the points

    layer = QgsVectorLayer('Polygon', 'poly' , "memory") pr = layer.dataProvider() poly = QgsFeature() points = [point1,QgsPoint(50,150),point2,QgsPoint(100,50)]

    or points = [QgsPoint(50,50),QgsPoint(50,150),QgsPoint(100,150),QgsPoint(100,50)]

    poly.setGeometry(QgsGeometry.fromPolygon([points])) pr.addFeatures([poly]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

-

it is not realy complicated, look at Memory provider in vector: :

  • a point is created with QgsPoint(x,y) and QgsGeometry.fromPoint(QgsPoint(x,y))
  • a line is created with two points: QgsGeometry.fromPolyline([QgsPoint(x1,y1),QgsPoint(x2,y2)]))
  • a polygon is created with a list of points: QgsGeometry.fromPolygon([[QgsPoint(x1,y1),QgsPoint(x2,y2), QgsPoint(x3,y3)]])

  1. two points:

    create a memory layer with two points

    layer = QgsVectorLayer('Point', 'points' , "memory") pr = layer.dataProvider()

    add the first point

    pt = QgsFeature() point1 = QgsPoint(50,50) pt.setGeometry(QgsGeometry.fromPoint(point1)) pr.addFeatures([pt])

    update extent of the layer

    layer.updateExtents()

    add the second point

    pt = QgsFeature() point2 = QgsPoint(100,150) pt.setGeometry(QgsGeometry.fromPoint(point2)) pr.addFeatures([pt])

    update extent

    layer.updateExtents()

    add the layer to the canvas

    QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. the line connecting the two points

    layer = QgsVectorLayer('LineString', 'line' , "memory") pr = layer.dataProvider() line = QgsFeature() line.setGeometry(QgsGeometry.fromPolyline([point1,point2])) pr.addFeatures([line]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

  1. a polygon covering the points

    layer = QgsVectorLayer('Polygon', 'poly' , "memory") pr = layer.dataProvider() poly = QgsFeature() points = [point1,QgsPoint(50,150),point2,QgsPoint(100,50)]

    or points = [QgsPoint(50,50),QgsPoint(50,150),QgsPoint(100,150),QgsPoint(100,50)]

    poly.setGeometry(QgsGeometry.fromPolygon([points])) pr.addFeatures([poly]) layer.updateExtents() QgsMapLayerRegistry.instance().addMapLayers([layer])

enter image description here

-

Changes in QGIS 3.0 and onward:

For QGIS 3.0 and onward the above workflow is still correct, but certain functions have changed. See https://qgis.org/api/api_break.html

To update the above code, change following functions:

QgsPoint -> QgsPointXY
QgsfromPoint -> QgsfromPointXY
QgsfromPolyline -> QgsfromPolylineXY
QgsfromPolygon -> QgsfromPolylineXY
QgsfromPolyline -> QgsfromPolylineXY
QgsMapLayerRegistry -> QgsProject
added 22 characters in body
Source Link
gene
gene
  • 55.4k
  • 3
  • 113
  • 191
Source Link
gene
gene
  • 55.4k
  • 3
  • 113
  • 191