I am trying to make a memory layer in QGIS using python and then generate a grid base on calculations in meters. When I run the script, a banner comes and says the CRS is not defined. Then when I look at the derived information I see that the area of the Geometry and its position is wrong.

vector_layer = QgsVectorLayer('Polygon?crs:epsg=3879&field=ID:integer(3)&field=value:double','test',"memory")
poly = QgsGeometry.fromPolygonXY([[
    QgsPointXY(34.18639744, 95.15668787),
    QgsPointXY(12.0161471 , 82.35668787),
    QgsPointXY(24.8161471 , 60.18643753),
    QgsPointXY(46.98639744, 72.98643753)])
f = QgsFeature(vector_layer.fields())

This code will generate a square, but the location is wrong. I tried to define CRS afterward in the code:

crs = vector_layer.crs()

But it did not work either. Can you please tell where I am making mistake?

  • 1
    your QgsVectorLayerisis not correct, the correct crs definition is crs=EPSG:3879 – Fran Raga Jun 9 '19 at 11:28

As Fran Fraga said, you probably have a typo in your layer definition. The reference system is set using “?crs=epsg:3879” and not “?crs:epsg=3879”.

Change the syntax and try again, it should solve your problem.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.