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[chiara modenese <c.modenese@xxxxxxxxx>]

Hi Vaclav,

two simple questions on python:

1) How do I apply a force (not the gravity) to the bodies? Which engine
should I call?

2) I get this error using the PeriodicPythonRunner engine to create some
plots:

NameError: name 'myAddPlotData' is not defined

But I defined the function in the python script so I do not understand why
it is giving me an error. Moreover if I try to access the data as
plot.data['fn'] it gives me an error, too.
I attach the python script.

Cheers,
Chiara

#!/usr/local/bin/yade-trunk -x
# -*- coding: utf-8 -*-
# -*- encoding=utf-8 -*-
##
## SCRIPT TO TEST A NEW CONSTITUTIVE LAW (MINDLIN)
## to run type ***execfile('/media/disk/DPhil/Class_Yade/Mindlin/test_mindlin.py')

O.initializers=[BoundDispatcher([Bo1_Sphere_Aabb(),Bo1_Box_Aabb()])]

## list of engines
O.engines=[
	ForceResetter(),
	BoundDispatcher([Bo1_Sphere_Aabb(),Bo1_Box_Aabb()]),
	InsertionSortCollider(),
	InteractionDispatchers(
		[Ig2_Sphere_Sphere_ScGeom(),Ig2_Box_Sphere_ScGeom()],
		[Ip2_FrictMat_FrictMat_MindlinPhys()],
		[Law2_ScGeom_MindlinPhys_Mindlin()]
	),
	GravityEngine(gravity=(-1000,0,0)), # here I would like to apply a force, not the gravity..
	NewtonIntegrator(damping=.2),
	###
	### NOTE this extra engine:
	###
	### You want snapshot to be taken every 1 sec (realTimeLim) or every 50 iterations (iterLim),
	### whichever comes soones. virtTimeLim attribute is unset, hence virtual time period is not taken into account.
	PeriodicPythonRunner(iterPeriod=20,command='myAddPlotData()')
]

## define and append material
mat=FrictMat(young=600.0e6,poisson=0.6,density=2.60e3,frictionAngle=26,label='Friction')
O.materials.append(mat)

## create two spheres (one will be fixed) and append them
from yade import utils
s0=utils.sphere([0,0,0],1,color=[0,1,0],dynamic=False,wire=True,material='Friction')
s1=utils.sphere([2,0,0],1,color=[0,2,0],dynamic=True,wire=True,material='Friction')
O.bodies.append(s0)
O.bodies.append(s1)

## time step
O.dt=.2*utils.PWaveTimeStep()

from yade import qt
qt.View()
qt.Controller()

############################################
##### now the part pertaining to plots #####
############################################

from math import *
from yade import plot
## make one plot: step as function of fn
plot.plots={'step':('fn')}

## this function is called by plotDataCollector
## it should add data with the labels that we will plot
## if a datum is not specified (but exists), it will be NaN and will not be plotted

def myAddPlotData():
	inter=O.interactions[0,1]
	## store some numbers under some labels
	plot.addData(fn=inter.phys.normalForce,step=O.iter,un=s0.shape['radius']-2*inter.phys.contactpoint[0])

# O.run(int(2./O.dt),True);

## We will have:
## 1) data in graphs (if you call plot.plot())
## 2) data in file (if you call plot.saveGnuplot('/tmp/a')
## 3) data in memory as plot.data['step'], plot.data['fn'], plot.data['un'], etc. under the labels they were saved