How to write data in binary file with python

[akohlmey]

@pierre

The display problem comes from the use of notepad++ to insert the python function part in the mail. I do not know how to avoid these typing errors.

No, it is not notepad++, it is you not quoting text correctly. I have briefly said how to correct this and a long explanation is here Please Read This First: Guidelines and Suggestions for posting LAMMPS questions

@pierre

However, I do not think that it is a problem of treating the data.

I disagree. You are not paying attention to what I explained.

@pierre

Another problem : when using the example in.fix_python invoke_neighlist, Lammps writes the message " No module named ‘numpy’ ".

Well, the way to resolve this is very straightforward: you must install the NumPy python module into your virtual environment (since the LAMMPS Python module uses NumPy)

Update: I cannot reproduce this. I just created a new virtual environment, installed the LAMMPS module and checked that NumPy was not installed in the virtual environment, and the in.fix_python_invoke example completes without an error. You must have made some modifications somewhere.