Workspace.prune only accepts lists

[alexander-held]

Summary

The docstring for Workspace.prune signals support for str arguments, but currently only lists are supported (tested for modifier types / samples / channels). This happens since _prune_and_rename iterates over its arguments without enforcing conversion to lists first. Happy to provide a MR to fix this behavior if desired, or update the docstrings to require list arguments.

OS / Environment

n/a

Steps to Reproduce

import pyhf

spec = {
    "channels": [
        {
            "name": "SR",
            "samples": [
                {"data": [10.0], "name": "Signal", "modifiers": []},
                {
                    "data": [112.0],
                    "modifiers": [
                        {
                            "data": {"hi_data": [67.0], "lo_data": [158.0]},
                            "name": "Modeling",
                            "type": "histosys"
                        }
                    ],
                    "name": "Background"
                }
            ]
        }
    ],
    "measurements": [
        {"config": {"parameters": [], "poi": ""}, "name": "minimal_example"}
    ],
    "observations": [
        {"data": [120.0], "name": "SR"}
    ],
    "version": "1.0.0"
}

ws = pyhf.Workspace(spec)
ws.prune(modifier_types=["histosys"])  # works fine
ws.prune(modifier_types="histosys")  # pyhf.exceptions.InvalidWorkspaceOperation
ws.prune(samples="Background")  # pyhf.exceptions.InvalidWorkspaceOperation
ws.prune(channels="SR")  # pyhf.exceptions.InvalidWorkspaceOperation

File Upload (optional)

No response

Expected Results

No exceptions raised.

Actual Results

Traceback (most recent call last):
  File "test.py", line 34, in <module>
    ws.prune(modifier_types="histosys")  # pyhf.exceptions.InvalidWorkspaceOperation
  File "[...]/pyhf/src/pyhf/workspace.py", line 638, in prune
    return self._prune_and_rename(
  File "[...]/pyhf/src/pyhf/workspace.py", line 513, in _prune_and_rename
    raise exceptions.InvalidWorkspaceOperation(
pyhf.exceptions.InvalidWorkspaceOperation: h is not one of the modifier types in this workspace.

pyhf Version

0.6.4.dev38

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