Introduction

The following example demonstrates how to use H2GIS with the Python scripting language. The advantage is the ability to run it on dedicated server without X11.

Requirements:

• To use H2GIS, you have to install Java from version 7.

Install H2GIS

To install H2GIS, follow this steps:

• Download the latest H2GIS version on the home page, unzip it.
• On Linux you can execute the following commands:

~ $ wget https://github.com/orbisgis/h2gis/releases/download/v1.3.2/h2gis-dist-1.3.2-bin.zip -O h2gis.zip
~ $ unzip h2gis.zip

Install psycopg2

http://initd.org/psycopg/docs/install.html#installation

Run H2GIS as a PosgreSQL sever mode

On Windows, Linux, Mac

java -cp "bin/*" org.h2.tools.Server -pg

Run Python script

python myscript.py

#!/usr/bin/python
from __future__ import print_function
import os


try:
    import psycopg2
except ImportError:
    print("Module psycopg2 is missing, cannot connect to PostgreSQL")
    exit(1)

def main():    
    #Define our connection string
    # db name has to be an absolute path
    db_name = (os.path.abspath(".")+os.sep+"mydb").replace(os.sep, "/")
    conn_string = "host='localhost' port=5435 dbname='"+db_name+"' user='sa' password='sa'"

    # print the connection string we will use to connect
    print("Connecting to database\n	->%s" % (conn_string))

    # get a connection, if a connect cannot be made an exception will be raised here
    conn = psycopg2.connect(conn_string)

    # conn.cursor will return a cursor object, you can use this cursor to perform queries
    cursor = conn.cursor()
    print("Connected!\n")

    # Init spatial features
    cursor.execute("CREATE ALIAS IF NOT EXISTS H2GIS_SPATIAL FOR \"org.h2gis.functions.factory.H2GISFunctions.load\";")
    cursor.execute("CALL H2GIS_SPATIAL();")
    print("Spatial functions added!\n")

   # Add spatial table and query it
    cursor.execute("DROP TABLE IF EXISTS VANNES;")
    cursor.execute("CREATE TABLE VANNES (the_geom geometry, id int);")
    cursor.execute("INSERT INTO VANNES VALUES('POLYGON ((100 300, 210 300, 210 200, 100 200, 100 300))'::geometry, 1),('POINT (100 100)'::geometry, 2);")
    cursor.execute("SELECT * FROM VANNES;")
    print("Show me the table:\n")
    rows = cursor.fetchall()
    for row in rows:
        print(row)
main()