Τη Παρασκευή, 16 Ιουνίου 2017 - 10:59:10 μ.μ. UTC+3, ο χρήστης Xristos Xristoou
έγραψε:
> I have create a python script where use post gis queries to automate some
> intersection tasks using postgis database.
>
> in my database I have polygons,points and lines.
>
> here my snippet code of my script :
>
> try:
> if str(geomtype) == 'point':
> geomtype = 1
> elif str(geomtype) == 'linestring':
> geomtype = 2
> elif str(geomtype) == 'polygon':
> geomtype = 3
> else:
> raise TypeError()
> sql = "\nDROP TABLE IF EXISTS {0}.{1};\nCREATE TABLE {0}.{1} AS (SELECT
> {4},\n(st_dump(ST_CollectionExtract(st_intersection(dbgis.{2}.shape,dbgis.{3}.shape)::GEOMETRY(GEOMETRY,2345),{5}))).geom
> AS shape\nFROM dbgis.{2}, dbgis.{3} WHERE
> st_intersects(dbgis.{2}.shape,dbgis.{3}.shape) AND {5}=3);\nCREATE INDEX
> idx_{2}_{3}_{6} ON {0}.{1} USING GIST (shape);\nALTER TABLE {0}.{1} ADD
> COLUMN id SERIAL;\nALTER TABLE {0}.{1} ADD COLUMN my_area double
> precision;\nUPDATE {0}.{1} SET my_area = ST_AREA(shape::GEOMETRY);\nALTER
> TABLE {0}.{1} ADD PRIMARY KEY (id);\nSELECT
> pop_g_col('{0}.{1}'::REGCLASS);\nGRANT ALL ON {0}.{1} TO GROUP u_cl;\nGRANT
> ALL ON {0}.{1} TO GROUP my_user;\n-- VACUUM ANALYZE
> {0}.{1};\n".format(schema, table, tablea, tableb, selects, geomtype, id_gen())
> return sql
> this post gis sql query work nice but I need the new field where I want to
> add my_area to create only for polygons layers.
>
> that code create for all layers (lines,points,polygons) that field my_area if
> layer is point or line then take value 0 I don't like that I don't need it.
>
> how to change this code to create my_area only in polygons ?
i wabt to ccreate a new field only in polygons layera
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