How to create .json files from VASP data to make training data for fitting SNAP Potential

How to create .json files from VASP data to make training data for fitting SNAP Potential

I am also want to know the techniques.

These are discussed in the maml package. Pymatgen is used by the maml package to generate the structure output files, but the actual fitting is done in the maml package. You may direct your questions to the Github issues page of that package. Thanks.