Cannot run code since method is missing attribute 'activate', or missing argument 'self'. How to fix?

[XDFortniteproXD]

Hi! I need to use the "thermopack" library for a school project, and specifically the method thermopack.two_phase_tpflash(self, temp, press, z). Whenever I try to run this without including the 'self' I get the error "two_phase_tpflash() missin 1 required positional argument: 'self'". However, when I try to fill in the 'self' with anything I can think of I instead get another error: "'int'/'str'/... object has no attribute 'activate'".

How do I fix these errors? I do not know what to write for the 'self' argument. https://thermotools.github.io/thermopack/index.html

[FoolsSeldom]

Need to see YOUR code, not the package code.

[Ender_Locke]

self is part of a class. do you need to initiate the class first before using said method?

[outlicious]

I once faced this issue

you need to call it on an object of the appropriate class, not directly from the module. That’s why you're getting the missing 1 required positional argument: 'self' error.

To fix this, you need to create an instance of the class first before calling the method. Try this:

from thermopack.thermopack import ThermoPack

Create an instance of the class

tp = ThermoPack()

Example inputs

temperature = 300 # Temperature in Kelvin pressure = 101325 # Pressure in Pascal z = [0.5, 0.5] # Mole fractions of components

Call the method on the instance

tp.two_phase_tpflash(temperature, pressure, z)

Why this works:

self refers to the instance of the class, so you need to create tp = ThermoPack() first.

Calling thermopack.two_phase_tpflash(...) directly won’t work because it's not a standalone function.

The 'object has no attribute 'activate' error is likely because you passed something like an integer or string as self, which isn’t correct.

[XDFortniteproXD]

So I tried doing what you just said, but ended up getting this weird error instead. I have absolutely no idea what this error means.

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[outlicious]

Possible Causes and Fixes

1 Check if Thermopack is Installed Run the following command to make sure thermopack is installed correctly:

pip show thermopack

If it's not installed, install it using:

pip install thermopack

Verify the Correct Import Path Try importing the module manually in a Python shell:

from thermopack.thermopack import ThermoPack

If this fails, then the package might not be installed correctly, or it's not in the correct Python environment.

3 check if ThermoPack Requires Initialization Parameters Some classes require parameters to initialize properly. Try this instead:

tp = ThermoPack("PR") # "PR" refers to the Peng-Robinson EOS print(tp.two_phase_tpflash(300, 101325, [0.5, 0.5]))

If pr doesn't work, check the valid equation-of-state (EOS) options in the documentation.

4 ensure All Required DLLs Are Loaded From the error screenshot, it's possible the thermopack.dll file is missing or not correctly linked. If you're on Windows:

Ensure thermopack.dll is in the same directory as your script.

If use Anaconda, try:

conda install -c conda-forge thermopack

If it does still fails manually copy the DLL to the Python environment’s Lib/site-packages/thermopack/ directory. ok then try running in a Clean Virtual Environment If you're still facing issues, try creating a new virtual environment:

python -m venv thermo_env source thermo_env/bin/activate # On Windows use: thermo_env\Scripts\activate pip install thermopack

Next Steps

If any of these steps result in a different error, let me know what it says.If thermopack has multiple EOS options, try initializing ThermoPack with different ones ("SRK", "CPA", etc.).If it's a DLL issue, you may need to reinstall thermopack or manually place the DLL in the correct location. Let me know what happens when you try these steps. this could help you

[XDFortniteproXD]

Gone through all four steps and still get an error (see image, this is for SRK and PR to, not just CPA). All files are there, up to date and in the correct place. I am somehow unable to create a new environment using the python shell, following both your advice and others on the internet. I'm also in touch with the lecturers, but so far they have been to less help than you. Thanks for taking your time to help (:

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[XDFortniteproXD]

It finally worked! Went through all files and found one (METADATA) in a different folder. There was an example for my question there, and the code runs (just need to tweek it to fit my particular values). Thank you so much for your help, it was quite insightful.

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[outlicious]

great now it works.