gns-science / opensha-py

python wrapper for opensha using py4j

README.md

opensha-py

A python bridge for opensha based on py4j.org

Taking the example from https://github.com/opensha/opensha-core/blob/master/src/org/opensha/sha/examples/HazardCurveCalcExample.java and wrapping it with a py4j gateway.

Now, we can do this in python...

#!python
from py4j.java_gateway import JavaGateway

gateway = JavaGateway()
hazard_calc_app = gateway.entry_point

print('HazardCurve calculation with default timespan = 30 years')
hazard_calc_app.execute(34.2, -118.344)

print('HazardCurve calculation with timespan = 50 years')
hazard_calc_app.setTimeSpan(50)
hazard_calc_app.execute(34.2, -118.344)

1.0 Python setup

prerequisites:

• python3
• py4j

2.0 Java compile

Note the opensha-py project is cloned into a folder containing the main opensha repos - see https://github.com/opensha/opensha-commons/blob/master/README.md)

The class path includes:

• the 'fat' opensha Jar file
• the py4j Jar
• opensha-py/src/java

export OPENSHA_PY_CLASSPATH=opensha-core/build/libs/opensha-core-all.jar:opensha-py/share/py4j/py4j0.10.9.jar:opensha-py/src/java:.
javac -cp $OPENSHA_PY_CLASSPATH opensha-py/src/java/org/opensha/py/HazardCurveCalcGateway.java 

3.0 Run the Java gateway server (background)...

java -cp $OPENSHA_PY_CLASSPATH org.opensha.py.HazardCurveCalcGateway

4.0 Call HazardCurveCalc from python client

python opensha-py/src/test_gateway.py