Create MultiPolygon from QgsGeometry.fromMultiPolygon

Question

I have a list of polygons' points like

[[x1,y1],[x2,y2],[x3,y3],[x4,y4]]   [[x5,y5],[x6,y6],[x7,y7].[x8,y8]]

now I want to create multipolygon from it by using

feature = QgsFeature()
feature.setGeometry(QgsGeometry.fromMultiPolygon([polygon_points]))

but it returns an error:

TypeError: QgsGeometry.fromMultiPolygon(): argument 1 has unexpected type 'list'

So how to make it right type for QgsGeometry.fromMultiPolygon()?

or maybe I am wrong with something?

======================Newly Update======================================

following is my point list

Points_list

My code read this list by

read_polygon=open('shapes_point.txt','rb')
polygons=[]
polygon_lines=read_polygon.readlines()  #read all polygons
for line in polygon_lines:              #read per polygon in polygons
  for points in line:                   #read per point in polygon
        x=points[0]
        y=points[1]
        Qgs_point=QgsPoint(float(x),float(y))
        polygons.append(Qgs_point)
feature = QgsFeature()
feature.setGeometry(QgsGeometry.fromMultiPolygon((QgsGeometry.fromMultiPolygon([polygons for polygon in polygons]))))

and returns me the error above

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I will try to make it more details

I want to read a shapefile in a dialog box, after some calculate progress, I will put values in each polygon features. The following is the main problem I have now!

I have the shapefile, and I want to fill it with color by values, but the method I only know is make a new polygon shapefile and append value to it

I don't know how to append the value in the selected polygon shapefile

So I use

feature = QgsFeature()
feature.setGeometry(QgsGeometry.Polygon([polygon_points]))

but it's always crash in multipolygons

so I want to know how to make multipolygons function need?

Answer 1

QgsGeometry.fromMultiPolygon() expects a list of polygons. A polygon, in turn, is a list of rings: An outer ring, and a number of inner rings. A ring, in turn, is a list of QgsPoint objects.

A valid MultiPolygon could thus look like this:

[ # The list of polygons
 [ # The list of rings for the first polygon
  [ # The list of QgsCoordinates
    QgsPoint(0,0), QgsPoint(1,0), QgsPoint(0,1)
  ]
 ],
 [ # The list of rings for the second polygon
  [ # The list of QgsCoordinates for the first polygon
    QgsPoint(2,2), QgsPoint(3,2), QgsPoint(2,3)
  ]
 ]
]

You can transform your list of coordinates into that structure using

[[[QgsPoint(point[0],point[1]) for point in polygon ] for polygon in polygon_points ]]

So to create the feature, you could use

feature.setGeometry(QgsGeometry.fromMultiPolygon([[[QgsPoint(point[0],point[1]) for point in polygon ] for polygon in polygon_points ]]))