Yaml generator changes to enable sweep tag

[dkazanc]

• Yaml generator changes to enable sweep runs
• New sweep pipeline directive

DiamondLightSource/httomo#628

[yousefmoazzam]

I think this does the job fine if the number of sweep values in all directives that want to do a manual sweep will have exactly 3 values.

If it's desired to be able to have a list of any number of sweep values, here's a minimal working example that demonstrates it:

import yaml


class SweepManual:
    """SweepManual class."""

    def __init__(self, lst):
        self._lst = lst


def __sweepmanual_representer(
    dumper: yaml.SafeDumper, swp: SweepManual
) -> yaml.nodes.SequenceNode:
    """Represent a sweepmanual as a YAML sequence node."""
    return dumper.represent_sequence("!Sweep", swp._lst)


def get_dumper():
    safe_dumper = yaml.SafeDumper
    safe_dumper.add_representer(SweepManual, __sweepmanual_representer)
    return safe_dumper


pipeline_data = [
    {
        "method": "FBP",
        "module_path": "httomolibgpu.recon.algorithm",
        "parameters": {
            "center": SweepManual([1, 2, 3, 4]),
            "filter_freq_cutoff": 0.35,
        },
    }
]

with open("sweep-tag-serialise.yaml", "w") as stream:
    stream.write(yaml.dump(pipeline_data, Dumper=get_dumper()))

[dkazanc]

Thanks Yousef, let me try to add it. Having something more generic is better.