Build Jzy3d charts for Python.

Jzy3d is a java library that can be invoked multiple ways :

• Py4j binding : python initialize a Java Virtual Machine acting like a server. Python scripts then exchange informations with this server. See src/main/python/py4j-*.py
• Jython : your python program is interpreted inside a JVM. It can use Java objects. See src/main/jython/jython-*.py

Py4j allows calling a Java Virtual Machine from Python. Py4j can call java methods and access java instance references.

pip install pyzy3d

from pyzy3d.pyzy3d import Pyzy3d
from pyzy3d.generator import Generator

pz = Pyzy3d()

# Generate data
n = 10000
coords = pz.new_coords(n)
Generator().scatter(coords, n)


# Drawable scatter
scatter = pz.new_scatter(coords)
scatter.setWidth(5.0)


# Chart
chart = pz.chart(0)
chart.getQuality().setSmoothPoint(True);
chart.add(scatter)
chart.open("Pyzy3d - Scatter", 800, 600)

pz.shutdown()

Will prompt

Console should show it started Py4j Gateway and connected successfully as follow:

Will start Pyzy3d Gateway : /Users/martin/Dev/jzy3d/public/pyzy3d/src/main/python/pyzy3d/bin/pyzy3d-1.0.1-SNAPSHOT.jar
Pyzy3d gateway invoked : /Users/martin/Dev/jzy3d/public/pyzy3d/src/main/python/pyzy3d/bin/pyzy3d-1.0.1-SNAPSHOT.jar
Joining Pyzy3d gateway ...
Pyzy3d gateway joined

and then show a scatter plot:

• Start a JVM using Pzy3d Jar file located in bin/
• Initialize a java Coord3ds to provide a java point cloud Reference
• Set coordinates and colors from python
• Open a Jzy3d chart

cd src/main/python # go to source folder if you are developing pyzy3d

python examples/example_scatter.py
python examples/example_surface.py

Surface example is interesting since it shows a way to define a function to render by the JVM gateway.

It will produce the below chart:

Surface example is based on pyzy3d default Func3d

from numpy import *

class Func3d(object):
    def __init__(self, monitor=False):
        self.k = 0
        self.doMonitor = monitor

    def f(self, x, y):
        self.monitor()
        return cos(x) + sin(y)

    def monitor(self):
        ...

    class Java:
        implements = ['org.pyzy3d.PyFunc3d']

Last line states that Func3d implements the PyFunc3d java interface. Overriding Func3d.f(x,y) let the JVM ask to python which Z value should be generated for a given {X,Y} pair.

• shutdown callback server when caller as finished processing
• detect if gateway is up or no to guess if it should be started
• flag to state if it should remain up + how to reconnect to callback server

• Kill a running instance of Py4j JavaGateway

lsof -n -i4TCP:25334 | grep LISTEN

Will show callback server process that might remain awake if Pyzy3d.shutdown() did not execute. Read process id and

kill [pid]

• https://python-packaging.readthedocs.io/en/latest/
• https://github.com/urbanairship/mvn-python-packaging/blob/master/pom.xml
• https://docs.python.org/3/distutils/setupscript.html#installing-additional-files
• https://blog.jetbrains.com/pycharm/2017/05/how-to-publish-your-package-on-pypi/

mvn clean package
cp target/pyzy3d-1.0.1-SNAPSHOT.jar src/main/python/pyzy3d/bin/

The java gateway sources are here

Verify you can run the python tests

cd src/main/python
pytest -svv

cd src/main/python
python setup.py sdist

Install pyzy3d with an alias so that updated source do not need re-install

pip install -e .

otherwise

pip install .

Now register for test deployement

twine register dist/pyzy3d-1.0.1.tar.gz -r testpypi

https://testpypi.python.org/pypi/pyzy3d

Now deploy to test

twine upload dist/* -r testpypi

• Mac OS brew install jython
• Other google install jython

./run-jython-scatter.sh
./run-jython-surface.sh

Compile as follow

mvn clean package
cp target/pzy3d-api-1.0.1-SNAPSHOT.jar bin/

Jython requires path to be defined as follow jython -Dpython.path=bin/pzy3d-api-1.0.1-SNAPSHOT.jar src/main/jython/jython-surface.py

Py4j requires gateway to be started with java -jar bin/pzy3d-api-1.0.1-SNAPSHOT.jar. Then run a script like python src/main/python/py4j-scatter.py