Following have two problems:
I am now have 4 point in a shapefile and I want to set the point's coordinate for boundary of a polygon
The points are xmin, xmax, ymin, ymax that can just be a rectangular polygon.
I want to make it to create a shapefile to make difference with another polygon shapefile
above problems i want to do it with python script
I use QGIS 1.8.0 and python 2.7.3