Maybe make a state to yaml function to save params

[ConnorStoneAstro]

It would be convenient to have a function which could save the state of a param DAG. Recording all the static params and identifying all the dynamic params.

[ConnorStoneAstro]

Seems like HDF5 can handle multiple paths to the same object. Maybe that would be a better structure for saving the param values?

Comments from ChatGPT about this:

In the HDF5 data model, the file is structured as a hierarchical collection of groups (similar to folders) and datasets (analogous to arrays). The key point for your question is that HDF5 supports multiple references (hard or soft links) to the same object, allowing you to maintain a DAG structure.

Hard Links

In HDF5, every object (group or dataset) is identified by a unique reference, and it is possible to create multiple hard links (akin to directory entries) that point to the same underlying object. This is somewhat analogous to hard links in a Unix filesystem.

• All hard links to an object share the same data and metadata.
• Deleting one hard link does not delete the object unless it is the last link.

Using hard links, a dataset or group can appear to reside in multiple locations in the hierarchy. This is exactly what you would want for a DAG structure where some nodes have multiple parents.

Example (using h5py):

import h5py
import numpy as np

with h5py.File("example.h5", "w") as f:
    # Create a dataset once
    data = f.create_dataset("leaf", data=np.arange(10))

    # Create two groups
    g1 = f.create_group("parent1")
    g2 = f.create_group("parent2")

    # Add hard links to the same dataset under each group
    g1["leaf"] = f["leaf"]
    g2["leaf"] = f["leaf"]

Now, both /parent1/leaf and /parent2/leaf refer to the same dataset /leaf.

[ConnorStoneAstro]

HDF5 is now implemented. It is very nice for storing chains when using the appendable=True option. However it is not very human readable, so a yaml version (that doesn't include an appending option) would still be very useful. The HDF5 save state can be used as a template