DM_shape_file_read.py

## @package python.demo.DM_shape_file_read
# 
# \brief read a polyline shape file including an used-defined attribute table.
# 
# Shape may contain points, polyline or polygon geometry objects. Furthermore, the corresponding
# dbf file contains an arbitrary number of attributes per geometry object which are imported as
# attribute. Per default all attributes are imported into an appropriate addinfo layout. Nevertheless,
# it is possible to import only a subset of attributes into a user-defined addinfo layout by the
# setAttributeMapping function as shown below.
# 
import sys, os
from opals import pyDM
 
def DM_read_shapefile(filename):
 
    # Create polygon and layout factory objects
    pf = pyDM.PolygonFactory()
    lf = pyDM.AddInfoLayoutFactory()
    lf.addColumn(pyDM.ColumnType.uint32, '_shapeId')  # internal shape object identifier. It's automatically set by the shape export
    layout = lf.getLayout()
 
    # Read table definition for the shape file
    tableDef = pyDM.ShapeTableDefinition.read(filename)
 
    # output table definition
    print(f"Shape file {filename} contains {tableDef.columns()} attributes:")
    print(f"idx name                   type     width   decimals")
    for i in range(tableDef.columns()):
        print(f" {i}\t{tableDef.name(i):16}{tableDef.type(i):10}{tableDef.width(i):10}{tableDef.decimales(i):10}")
 
    # Create shape export with the
    print(f"Open shape file '{filename}'")
    imp = pyDM.ImportShape(filename)
 
    # create mapping between dbf attributes and the defined layout (optional)
    # per default all attributes will be imported
    mapping = {tableDef.name(0): 0, }          # import dbf attribute Id as column 0 of layout (_shapeId)
    imp.setAttributeMapping(layout, mapping)   # use attribute column 0 as automatically filled counter
 
    print("Read files...")
    for idx, obj in enumerate(imp):
        print(f" Geometry {idx} is a {obj.type()} and contains {obj.sizePoint()} points (_shapeId={obj.info().get(0)})")
        for pt_idx, pt in enumerate(obj.points()):
            print(f"  {pt_idx:3}.point {pt.x:12.3f}, {pt.y:12.3f}, {pt.z:9.3f}")
    print("Done")
 
 
if len(sys.argv) < 1:
    print("shape file parameter missing")
    sys.exit(-1)
 
DM_read_shapefile(sys.argv[1])