mapdl.parameters on vector from mapdl.starvget

[iceblink-ansys]

Hi, I would like to get access to some node numbers and stress results that I retrieve from a result file, using the mapdl.starvget method. When I try to do that, I get an error "ValueError: cannot reshape array of size 0 into shape (25,1,1)"
Is this a bug, or should I prepare my variable first so that it has the right size, before using mapdl.parameters ?

Something like:

mapdl.cwd(dirpath=os.getcwd())
mapdl.post1()
mapdl.inres(item1='ALL')
mapdl.file(fname='v18.rst')
mapdl.set(lstep='FIRST')
mapdl.cmsel(type_='S', name='DUMMY_CMP')
mapdl.starvget(parr='CMP_NODENUMS', entity='NODE', item1='NLIST')
node_num_list = mapdl.parameters['CMP_NODENUMS']

Update

I found out I should be able to do:

mapdl.get_array('NODE', item1='NLIST')

but that returns an array of length zero, even though I am sure I have selected nodes

>>> mapdl.cmsel(type_='S', name='DUMMY_CMP')
SELECT      COMPONENT DUMMY_CMP
>>> mapdl.get(par='TOT_NODES', entity='NODE', item1='COUNT')
25.0
>>> mapdl.get_array('NODE', item1='NLIST')
array([], dtype=float64)

[germa89]

Hi @iceblink-ansys

Can I get the RST file? So I can work on the exact same issue?

[iceblink-ansys]

Hi @germa89 sorry for the delay. Please find attached the needed files.
getarray_problem.zip

The problem may be related to the way mapdl works. If I try the same in an CLI-mapdl session using normal APDL, *VWRITE gives unexpected results, i.e. when using C-style formatting it does not output nodenumbers, when using Fortran style formatting it only works using float. From the *VWRITE help: "If you are in the GUI, the *VWRITE command must be contained in an externally prepared file and read into ANSYS (i.e., *USE, /INPUT, etc.)." In batch mode it works fine. Maybe you can use this knowledge to your advantage. Let me know if you want more details on this.

[germa89]

Regarding the formatting issues, *VWRITE can only be used in batch mode or inside an external file (using /INPUT). That's why you had that message:

"If you are in the GUI, the *VWRITE command must be contained in an externally prepared file and read into ANSYS (i.e., *USE, /INPUT, etc.)."

If you want to do anything with *VWRITE you need to write the commands in an external file, for example:

my input file input.dat

*CFOPEN,myfile,txt
*VWRITE, LABEL(1), VALUE(1, 1), VALUE(1, 2), VALUE(1, 3)
(1X, A8, '   ', F10.1, '  ', F10.1, '   ', 1F5.3)
*CFCLOSE

And then in the GUI, issue:

/INPUT,myfile,txt

[iceblink-ansys]

Hmmm, I am not really in the GUI, but in PyAnsys.
Also, this is not very Pythonic.

But I guess this is what I can expect when using APDL commands via Python.

Unless it can maybe be fixed for mapdl in some future version? After all, this limitation does not make a lot of sense, no matter if you are in a GUI or not. (This is probably one of those things that everyone agrees should be fixed, but nobody wants to take any risk of changing software just to please that one user who complained about it, lol.)

[germa89]

Hmmm, I am not really in the GUI, but in PyAnsys.
Also, this is not very Pythonic.

The formatting issues you mention is GUI related, it only happens on MAPDL. In PyMAPDL you don't need to deal with "*VWRITE". Or are you using interactively?

[iceblink-ansys]

Hmmm, I am not really in the GUI, but in PyAnsys.
Also, this is not very Pythonic.

The formatting issues you mention is GUI related, it only happens on MAPDL. In PyMAPDL you don't need to deal with "*VWRITE". Or are you using interactively?

True, after that last main branch fix, writing with Python is the way to go.

[germa89]