ppygis3

ppygis3 is a port of PPyGIS that works in Python>=3. PPyGIS is an extension for psycopg2. PPyGIS adds support for PostGIS geometry objects by translating them between PostGIS EWKB representation and python objects.

Installation

pip install ppygis3

Usage

The module can be used exactly as described in the documentation of PPyGIS for Python2. Simply use a different import statement, ppygis3 instead of PPyGIS. The PPyGIS documentation can be found here

Basic Usage (Read, Write)

Adapted from the original documentation. By extending the psycopg2 module, geometry objects will be automatically serialized when inserting and transformed to python objects when loading.

import psycopg2
from ppygis3 import Point, LineString, Geometry

# Connect to an existing spatially enabled database
connection = psycopg2.connect(database='test', user = 'test')
cursor = connection.cursor()

cursor.execute('CREATE TABLE test(geometry GEOMETRY)')

# Insert a point into the table
cursor.execute('INSERT INTO test VALUES(%s)', (Point(1.0, 2.0),))

# Retrieve the point from the table and print it
cursor.execute('SELECT * FROM test')
point = cursor.fetchone()[0]
print(point)

# Create a line and insert it into the table
geometry = LineString((point, Point(4.0, 5.0, 6.0)))
cursor.execute('INSERT INTO test VALUES(%s)', (geometry,))

# Retrieve the table contents and print it
cursor.execute('SELECT * FROM test')
for row in cursor:
    print(row[0])

# Disconnect from the database
cursor.close()
connection.close()

COPY FROM/TO

COPY FROM and TO allow for bulk uploads and downloads. The following shows example usage of this functionality.

import psycopg2
from ppygis3 import Point, LineString, Geometry
from io import BytesIO

# Connect to an existing spatially enabled database
connection = psycopg2.connect(database='test', user = 'test')
cursor = connection.cursor()

cursor.execute('CREATE TABLE test(geometry GEOMETRY)')

buffer = BytesIO()
buffer.write(Point(1.0, 2.0).write_ewkb() + b'\n')
buffer.write(LineString((Point(1.0, 2.0), Point(3.0, 4.0))).write_ewkb() + b'\n')
buffer.seek(0)

# Perform a bulk upload of data to the table
cursor.copy_from(buffer, 'test')

# Retrieve the table contents and print it
cursor.execute('SELECT * FROM test')
for row in cursor:
    print(row[0])

# Perform a bulk download of data from the table
buffer = BytesIO()
cursor.copy_to(buffer, 'test')
buffer.seek(0)

# Print the data
for line in buffer:
    print(Geometry.read_ewkb(line.strip()))

# Disconnect from the database
cursor.close()
connection.close()