<!-- GENERATED by tools/generators/examplesDocsEmitter.py from python/ - do not edit -->
(testmodels-sensoruserfunctiontest)=
# sensorUserFunctionTest.py

You can view and download this file on Github: [sensorUserFunctionTest.py](https://github.com/jgerstmayr/EXUDYN/tree/master/python/TestModels/sensorUserFunctionTest.py)

```{code-block} python
:linenos:

#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
# This is an EXUDYN example
#
# Details:  Test sensor with user function
#
# Author:   Johannes Gerstmayr
# Date:     2021-02-18
#
# Copyright:This file is part of Exudyn. Exudyn is free software. You can redistribute it and/or modify it under the terms of the Exudyn license. See 'LICENSE.txt' for more details.
#
#+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

import exudyn as exu
from exudyn.itemInterface import *

from math import pi, atan2

testIsActive = exu.sys.get('testIsActive', False)

SC = exu.SystemContainer()
mbs = SC.AddSystem()
node = mbs.AddNode(NodePoint(referenceCoordinates = [1,0,0], 
                             initialCoordinates=[0,0,0],
                             initialVelocities=[0,1,0]))
mbs.AddObject(MassPoint(nodeNumber = node, mass=1))

sNode = mbs.AddSensor(SensorNode(nodeNumber=node,
                                 fileName='solution/sensorTestPos.txt',
                                 writeToFile = (not testIsActive), #no output needed
                                 outputVariableType=exu.OutputVariableType.Position))

def UFsensor(mbs, t, sensorNumbers, factors, configuration):
    val = mbs.GetSensorValues(sensorNumbers[0]) #x,y,z
    phi = atan2(val[1],val[0]) #compute angle from x,y: atan2(y,x)
    #print("phi=", factors[0]*phi)
    #print("x,y,z", val)
    return [factors[0]*phi] #return angle in degree

sUser = mbs.AddSensor(SensorUserFunction(sensorNumbers=[sNode], factors=[180/pi], 
                                 storeInternal=True,#fileName='solution/sensorTestPhi.txt',
                                 writeToFile = (not testIsActive),
                                 sensorUserFunction=UFsensor))

#assemble and solve system for default parameters
mbs.Assemble()

simulationSettings = exu.SimulationSettings() #takes currently set values or default values
simulationSettings.solution.file.write = False

mbs.SolveDynamic(simulationSettings)

#evaluate final (=current) output values
u = mbs.GetSensorValues(sUser)
exu.Print('sensor=',u)

exu.sys['testResult'] = u #should be 45 degree finally

#+++++++++++++++++++++++++++++++++++++++++++++++++++++
if not testIsActive:
    
    mbs.PlotSensor([sNode, sNode, sUser], [0, 1, 0])
```