Saving and loading operators

HDF5 files

operator_list_to_h5 / h5_to_operator_list save an arbitrary list[Operator] to a single portable .h5 file and reload it later, preserving every attribute needed to reconstruct each operator exactly, including gamma_pol_index, so a custom polarisation matrix set via set_polarization_matrix() survives the round trip. This is a lighter-weight alternative to make_operator_database for saving an ad-hoc selection of operators (e.g. the output of get_paper_operators, or operators built by hand) rather than a full database:

from h4lat import get_paper_operators, operator_list_to_h5, h5_to_operator_list

ops = get_paper_operators("Rodekamp:2023wpe")  # any list of Operator objects
operator_list_to_h5(ops, "my_operators/selection.h5")

# ... later, possibly in a different session ...
reloaded = h5_to_operator_list("my_operators/selection.h5")
assert [op.id for op in reloaded] == [op.id for op in ops]

Requires h5py (pip install "h4lat[full]" or "h4lat[operators]"). Under the hood, each operator is stored in its own group and (de)serialised with write_operator / read_operator, which can be used directly if you need to embed a single operator inside a larger, custom HDF5 layout of your own. Fields that are None (e.g. the id of a sum of operators) are stored too.

One file per operator

op.save(folder) writes the cgmat of an operator to a .npy file whose name holds all the other information, in the format of the operator database, and Operator_from_file(path) reads it back. Since the file name cannot store None, save refuses operators without id, irrep, block or index_block, such as the sums built with + or -: save those with operator_list_to_h5.