print() Error

[james12parker]

I am attempting to print the location of the object.

According to this discussion on GitHub - #207, it appears that you can access the force and other information through the SOFA UI. However, I am hoping to receive this information in real-time during the simulation.

According to this discussion on GitHub - #3002, it appears that the position information is stored in the MechanicalObject and can print the info using print(). To access it, I followed the code below:

self.MO = kwargs.get("MechanicalObject")
print(str(self.MO.position))

However, I keep encountering the following error:

[ERROR]   [SofaPython3::SceneLoader] Unable to completely load the scene from file 'projects/SOFA/scene.py'.  
Python exception:   
  TypeError: print(): incompatible function arguments. The following argument types are supported:
    1. (arg0: Sofa.Core.Node) -> None

Invoked with: "Sofa.Core.DataContainer <name='position', address=0x5557146459c0>"

Basically, I cannot print anything and I am unsure why. I have a SofaPython plugin, and when I attempted to also call the DataContainer plugin, it resulted in a fatal error. I am unsure of what I might have overlooked.

Thank you~

[alxbilger]

Hi,

you can have a look on the documentation website. It mentions the need to add .value after a Data. Also, make sure that self.MO is the MechanicalObject. We cannot say it from what you shared, because we don't know what you put in kwargs.

[damienmarchal]

Hi @james12parker,

As pointed by @alxbilger, to get the value of a data field you need to use the "value" attribute.
That's said I don't understand why you get this weird error message.
I tried the following

import Sofa

class AClass(object):
	def __init__(self, **kwargs):
	    self.MO = kwargs.get("MechanicalObject")
	    print(str(self.MO.position))                              
	    print(str(self.MO.position.value)) 

def createScene(root):
    """This scene is just one mechanical object with position that are printed by a function"""
    mo = root.addObject("MechanicalObject")
    AClass(MechanicalObject=mo)
    
createScene(Sofa.Core.Node("root"))

And, as expected it prints

dmarchal@dmarchal-Precision-7550:~/projects/dev/test/sofa_args$ python3 test.py 
---------------------------------------
Checking SOFA_ROOT and SOFAPYTHON3_ROOT
Using environment variable SOFA_ROOT: /home/dmarchal/projects/dev/sofa1/build-clang3/
---------------------------------------
Sofa.Core.DataContainer <name='position', address=0x10c1910>
[[0. 0. 0.]]

without the error.

[hugtalbot]

did Damien's comment help you @james12parker ?