Docstring Style Guide

This is the single source of truth for how docstrings are written in AAanalysis. The mature classes CPP, AAclust, and dPULearn are the gold standard — every public symbol should read as if written by the same hand.

The guide is enforced by an internal checker (.claude/skills/docstrings/scripts/check_docstrings.py); run it before and after touching any docstring. All other docstring notes in the repository (the always-on .claude/rules/docstrings.md, the docstrings skill, and the Docstring Style section of CONTRIBUTING) are thin pointers to this page and define no rules of their own.

Style basis: numpydoc + PEP 257. Sections appear in the numpydoc order Parameters → Returns → Raises → Notes → Warnings → See Also → References → Examples.

Class docstrings

class AAclust(Wrapper):
    """
    Amino Acid clustering (**AAclust**) class: a k-optimized clustering wrapper
    for selecting redundancy-reduced sets of numerical scales [Breimann24a]_.

    <One expanded paragraph of purpose; optionally a ``*``-bulleted breakdown.>

    .. versionadded:: 0.1.0

    Attributes
    ----------
    labels_ : array-like, shape (n_samples,)
        Cluster labels in the order of samples in ``X``.
    """
    def __init__(self, model_class=KMeans, verbose=True, random_state=None):
        """
        Parameters
        ----------
        random_state : int, optional
            The seed used by the random number generator. If a positive
            integer, results of stochastic processes are consistent, enabling
            reproducibility. If ``None``, stochastic processes are truly random.

        Notes
        -----
        * <cross-cutting caveats>

        See Also
        --------
        * :class:`AAclustPlot`: the respective plotting class.

        Examples
        --------
        .. include:: examples/aaclust.rst
        """

Invariants:

• Summary is a noun phrase (<Full Name> (**ACRONYM**) class ...) on the line after a blank first line, present tense; not an imperative verb.

• Citations are the exception, not the default. A class earns a [Key]_ citation only when it is an important class that a specific reference describes — its own paper, or the project paper [Breimann25]_ for the core γ-secretase CPP / dPULearn / TreeModel algorithms it covers. Most classes — every data-prep / utility / helper class (preprocessors, loaders, :class:`~aaanalysis.NumericalFeature`, :class:`~aaanalysis.AALogo`, …) — carry no citation, and that is correct, not a gap. Never add one to satisfy a checker note. Verify before adding, and never invent one: the key must be defined in references.rst (the checker’s CITATION-UNDEFINED flags typo’d / fabricated keys) and the cited work must actually describe this class. CLASS-NO-CITATION is advisory — a reminder to confirm an important class isn’t missing its citation, not a prompt to cite utilities; a wrong citation is worse than none.

• .. versionadded:: follows the prose, before any section.

• The class docstring carries only Attributes (scikit-learn _-suffixed fit-state), documented as name_ : type, shape (...). Stateless classes omit it.

• Parameters belong in __init__ — never in the class docstring. __init__ always has a docstring, ordered Parameters → Notes → See Also → Examples.

• Plot pairs are reciprocal: a Plot class summary reads Plotting class for :class:`<X>` ... [Key]_. and the logic/plot classes link each other under See Also.

Method & function docstrings

def run(self, labels=None, ...):
    """
    Perform Comparative Physicochemical Profiling (CPP): creation and two-step
    filtering of interpretable sequence-based features.

    Parameters
    ----------
    labels : array-like, shape (n_samples,)
        Class labels for samples in sequence DataFrame (typically, test=1,
        reference=0).

    Returns
    -------
    df_feat : pd.DataFrame, shape (n_features, n_feature_info)
        Feature DataFrame; output-column schema as ``*`` bullets in Notes.

    See Also
    --------
    * :meth:`CPP.eval`: evaluate the resulting feature set.

    Examples
    --------
    .. include:: examples/cpp_run.rst
    """

Invariants:

• Summary is a verb phrase (imperative/present); no → / + / arrow shorthand.

• Summary + description. The one-line summary is followed (after a blank line) by a short plain-language description — what it does in simple words, the cited tool/method [Key]_ if it integrates one, and the key :role: cross-references — before the first section. The same holds for classes (the expanded paragraph after the noun-phrase summary). Trivial one-line accessors may keep just the summary; the checker’s SUMMARY-ONLY is advisory, a prompt to add the description where it helps. Write the description as natural flowing prose; do not prefix it with a bold rhetorical label that names the meta-idea (**Mental model.**, **When to use.**, **What it returns.**) — state the content directly. (Bold for genuine emphasis or a structural *-bullet label in Notes is fine; this rule is only about replacing the explanatory paragraph with a bold heading.)

• Expand abbreviations on first use. The first time an abbreviation or acronym appears in a docstring, spell it out with the short form in parentheses — Command Line Interface (CLI), Position Weight Matrix (PWM), Find Individual Motif Occurrences (FIMO) — and use the short form afterwards. Each docstring is self-contained, so re-introduce the term in every docstring that uses it. The bold (**ACRONYM**) in a class summary is the class-level form of this rule. Domain terms that have a .. glossary:: entry may instead be linked with :term:. Universally standard forms (e.g. DNA, 3D, ID, CPU, PDB) need no expansion.

• Returns is named (name : type) and matches the returned variable. Two type-only idioms are allowed: a bare class name (scikit-learn self-return, e.g. AAclust) and a polymorphic X or Y.

• Fixed-option parameters use Literal, not str. When a parameter accepts a closed, finite set of string options (the values a check_str_options /membership check validates against), type-hint it in the signature as typing.Literal["a", "b", ...] rather than a bare str — so the allowed set is self-documenting and IDE-checkable. Spell the members as inline string literals: Literal cannot reference the ut.X constants, even though the runtime validator still uses them. If the parameter also accepts None (default None or accept_none=True), wrap as Optional[Literal[...]] (never put None inside Literal); if it also accepts non-string values, use Union[Literal[...], <other>]. In the docstring, type the parameter with numpydoc set notation matching the members — name : {'remove', 'keep', 'gap'}, default='remove' — not name : str. Open or large sets (e.g. system font names) stay str.

• Explain each option as a nested bullet. When the options are not self-evident from their names, follow the set-notation type line with a short lead-in and a nested - bullet list — one bullet per option, each naming the option value (in double backticks) followed by : and a concise gloss, e.g. an option 'remove' documented as “drop sequences with non-canonical amino acids”. Keep the gloss to what the option is / when to pick it; defer fuller behaviour to Notes and point there with (see Notes). These per-option enumerations are the exception to the ``*``-bullet rule below: option sub-lists under a parameter use - (matching name / non_canonical_aa / logo_type), while Notes and See Also section bullets use *.

• The section header is Warnings, never Warns.

• List items use * bullets, not -.

• Every public method ends with Examples → exactly one .. include:: examples/<name>.rst (no other path or extension).

Recurring parameters (DRY)

Parameters that appear in many signatures share one baseline sentence; method-specific behaviour is a suffix, never a replacement. Describe the structure first, the use second.

df_seq        DataFrame containing an ``entry`` column with unique protein
              identifiers and a ``sequence`` column with full protein sequences.
labels        Class labels for samples in sequence DataFrame (typically,
              test=1, reference=0).
n_jobs        Number of CPU cores (>=1) used for multiprocessing. If ``None``,
              the number is optimized automatically. If ``-1``, all cores are
              used. Overridden by ``options['n_jobs']`` when set.
random_state  The seed used by the random number generator. If a positive
              integer, results are reproducible; if ``None``, truly random.

To keep these from drifting, define each baseline once and inject it with a pandas/seaborn-style mechanism (a _shared_docs dict + a @doc(...) / Substitution decorator) rather than re-typing it. This is the adopted target; where injection is not yet wired, copy the baseline verbatim.

A docstring is self-contained — document every parameter as its own entry. DRY means reusing the same sentence, not collapsing parameters into a single cross-method reference. Never write a lumped entry like labels, n_filter, n_jobs, ... : See :meth:`run`. Same semantics. — repeat each parameter (with its baseline sentence) so the reader never has to open another method to learn what an argument does. The checker’s PARAM-UNDOCUMENTED flags the signature parameters such a lump leaves effectively undocumented.

Cross-references (See Also)

• Roles: :class: (classes), :meth: (methods), :func: (top-level / scikit-learn functions), :ref: (usage-principles pages), :term: (glossary terms, see below).

• See Also is a *-bulleted list; each entry is * :role:`Target`: gloss. — single colon, gloss after : ``. No bare ``name : desc numpydoc entries and no `` : `` (space-colon-space).

• Every cross-reference must resolve. A :class:/:meth:/:func: target (in See Also or inline prose) must name a real public symbol — CPP, run_num(), aaanalysis.combine_dict_nums. Watch capitalization (AALogo, not AALogo) and method names on the right class. The checker’s XREF-UNRESOLVED flags an internal target that does not resolve; external refs (pandas.DataFrame) are left alone.

• Order multi-layer links by documentation layer. When a See Also (or inline prose) links out to other documentation layers, reference them in the order Usage Principles → Tables → Tutorials. Add an external-library reference only when absolutely necessary.

Citations

• Cite inline with [Key]_ only. Never inline a full .. [Key] Author, Year, ... reference, a raw URL, or (Author et al. Year) free text.

• All bibliography entries live in docs/source/index/references.rst, grouped by topic. Key format: single first-author [AuthorYY] ([Song12]), two-author [FirstSecondYY] ([ElkanNoto08]), same author/year gets a trailing letter ([Breimann24a]).

• Pick the few most relevant references per symbol — 1–2 per major method, plus the project paper ([Breimann25]_) at the class level only for the classes that paper actually describes (the core CPP / dPULearn / TreeModel pipeline). It is not a default stamp: a class the cited work does not cover carries no class-level citation (see the class-summary rule above).

• Every external tool / method AAanalysis integrates must be cited and explained. When a method wraps or runs an external tool (DSSP, Chainsaw, Merizo, AFragmenter, MEME / FIMO, cd-hit, mmseqs2, logomaker, SHAP, …), name it with a [Key]_ citation (its paper, defined in references.rst — verify it exists, never a bare repo URL) and describe what the tool does in one plain sentence. Example: 'chainsaw' ([Wells24]_): a fully-convolutional neural network that predicts domain boundaries from a PDB / CIF structure.

• Never reference internal decision records (ADRs) in docstrings. ADRs (docs/adr/) are internal to the development process; docstrings are user-facing. If an ADR documents a user-visible choice (why a parameter exists, how an algorithm was selected), extract the why as plain language in the docstring — never cite the ADR number. (Developer-facing notes such as CONTEXT.md may cite ADRs; user docstrings may not.)

Versioning & deprecation

• .. versionadded:: X.Y.Z (true first-release version) on every public class and function; .. versionchanged:: X.Y.Z when behaviour changes.

• Parameter-level directives — when a parameter or option is added/changed after its class, annotate it inside the parameter description:

  return_stats : bool, default=False
      If ``True``, also return the filter-funnel statistics.
  
      .. versionadded:: 1.1.0
  

• Deprecation uses .. deprecated:: X.Y.Z in the docstring plus a DeprecationWarning shim (see api-stability); a renamed/removed public symbol keeps a one-minor-release shim before removal.

Class abbreviations

Every public class has one canonical abbreviation, used identically as the example-notebook instance variable (aac = aa.AAclust()) and the example-notebook filename stem (examples/feature_engineering/aac_fit.ipynb). This keeps the API, the example notebooks, and the rendered docs in lock-step. The registry below is the single source of truth and is enforced by tests/unit/api_tests/test_class_abbreviation_registry.py (every public class is registered; every <abbr> = aa.<Class>() and notebook filename matches).

How an abbreviation is formed (in priority order):

• Keep the recognizable name prefix. AA* classes keep aa; Seq* classes keep seq; a genuine acronym stays whole (CPP → cpp); an established public spelling is kept (dPULearn → dpul).

• Then add the first letter of each remaining CamelCase word. So AAWindowSampler → aaws, SequenceFeature → sf, NumericalFeature → nf, TreeModel → tm, ShapModel → sm, AAclust → aac, AALogo → aal, AAMut → aam, AAPred → aap, SeqMut → seqm, SeqOpt → seqo.

• Extend a component when the minimal initial is too generic or would collide. The *Preprocessor family therefore uses a three-letter first-word stem plus p — SequencePreprocessor → seqp, EmbeddingPreprocessor → embp, StructurePreprocessor → strp, AnnotationPreprocessor → annp — because two-letter initials (sp/ep) are too generic and clash. On a direct collision the newer class takes the longer form: SeqMut is seqm, leaving sm free for ShapModel.

• Reserved: ap is the import alias for aaanalysis.pipe (import aaanalysis.pipe as ap) and is never a class abbreviation.

• A plot pair is the base abbreviation plus _plot (CPPPlot → cpp_plot).

• A class instance is named the bare abbreviation, always — cpp = aa.CPP(...), never cpp_res/cpp_dom. If you build the same class repeatedly (e.g. one CPP per prediction level), reassign the bare name and let the outputs carry the qualifier (df_feat_res, X_res). A <abbr>_<qualifier> instance name is allowed only for a genuinely concurrent second instance that cannot be restructured (aaws_strict beside aaws) — never an unrelated word.

Type-suffix mnemonic. Four class families encode their kind in the last letter of the abbreviation, so a reader can tell what a variable holds at a glance. The remaining tool / engine classes keep the prefix + concept-initial form above (cpp, aac, aam, seqm, seqo, aap, aaws, dpul).

Abbreviation type-suffix map

Suffix	Family	Members
*p	preprocessors	seqp, embp, strp, annp
*f	feature containers	sf, nf
*m	models (fit / produce a model or estimate)	tm, rm, sm
*x	XAI explainers (post-hoc; planned — see Reserved future abbreviations)	fx, cx, ex, rx, nx, sx
*_plot	plot companions	cpp_plot, aap_plot, seqo_plot

The full registry follows, grouped by pipeline stage in the exact order of the API reference, so reading top-to-bottom traces the same workflow (load → sequence analysis → features → PU learning → model → predict → engineer). The left column links to each API section; the Extra column marks pro-extra classes. Within a stage, a logic class and its *Plot companion share one row, and parallel-modality families run sequence → structure → embedding → annotation.

Canonical class abbreviations (ordered as the API reference)

Section	Class	Abbr.	Extra
Data Handling	SequencePreprocessor	seqp
	StructurePreprocessor	strp	pro
	EmbeddingPreprocessor	embp
	AnnotationPreprocessor	annp	pro
Sequence Analysis	AALogo / AALogoPlot	aal / aal_plot
	AAWindowSampler	aaws
Feature Engineering	AAclust / AAclustPlot	aac / aac_plot
	SequenceFeature	sf
	NumericalFeature	nf
	CPP / CPPPlot	cpp / cpp_plot
	CPPGrid	cppg
	CPPStructurePlot	cpps_plot	pro
PU Learning	dPULearn / dPULearnPlot	dpul / dpul_plot
Explainable AI	TreeModel	tm
	ShapModel	sm	pro
Prediction	AAPred / AAPredPlot	aap / aap_plot
	ReliabilityModel / ReliabilityModelPlot	rm / rm_plot
Protein Engineering	AAMut / AAMutPlot	aam / aam_plot
	SeqMut / SeqMutPlot	seqm / seqm_plot
	SeqOpt / SeqOptPlot	seqo / seqo_plot	core (mode="impact" needs pro)

Reserved future abbreviations

The v2 Explainability (XAI) layer will add one *Explainer class per method category, each wrapping several library approaches as methods (one method per approach). Their abbreviations follow the *x (explainer) suffix and are reserved now so they are not reused before the classes land. The shipped *Model wrappers — TreeModel (tm), ReliabilityModel (rm), ShapModel (sm, kept as the legacy SHAP wrapper) — stay unchanged.

Reserved XAI *Explainer abbreviations (planned, not yet implemented)

Class (planned)	Abbr.	Scope	Wraps (one method per approach)
FeatureExplainer	fx	pro	permutation importance, PDP, ICE, ALE, LIME
ExampleExplainer	ex	core / pro	prototypes (AAclust medoids, MMD-CRITIC), counterfactuals (Wachter, DiCE, CEM)
RuleExplainer	rx	pro	ANCHOR, RuleFit, LORE, TREPAN
NeuralExplainer	nx	pro	integrated gradients, LRP, Grad-CAM, TCAV (Captum)
SurrogateExplainer	sx	core / pro	tree / linear / symbolic distillation of a fitted model
CausalExplainer	cx	pro	DoWhy, EconML

Each planned class gets a plot companion (fx_plot, ex_plot, …). The PascalCase pass for AALogo / AALogoPlot (abbreviations aal / aal_plot unchanged) is done; the former AAlogo / AAlogoPlot names remain importable as deprecated back-compatible aliases (resolved via aaanalysis.__getattr__ with a DeprecationWarning).

Tutorial notebook titles

A tutorial notebook’s first # heading is its rendered page title and the sidebar link text, so the titles must stay consistent across the tutorial set. A tutorial centred on a single public class is titled

<ClassName>: <capability phrase>

— the exact public class name (as in the API), a colon, then a short phrase for what the reader learns. Examples already in the set: AAclust: Selecting redundancy-reduced scale sets, SequenceFeature: Creation of CPP feature components, CPP: Identification of physicochemical signatures, dPULearn: Learning from unbalanced data, ShapModel: Explaining with single-residue resolution, CPPGrid: Sweeping, evaluating, and ranking configurations, SeqOpt: Optimizing sequences by directed evolution.

Rules:

• No ``Tutorial`` word or number in the title (never Tutorial 6 — … or Tutorial: …). Ordering lives in the filename (tutorial6_*) and the tutorials.rst toctree, not the heading.

• When a section of tutorials.rst introduces the notebook in prose, name it by the same class (the CPPGrid tutorial, the SeqOpt tutorial) so the prose, the title, and the API all read the same.

• A tutorial that teaches a function or a cross-cutting topic rather than one class uses a plain descriptive title — Data loading, Scale loading, CPP across data representations.

• The onboarding notebooks under Getting Started (A minimal CPP analysis, Quick start with AAanalysis, Slow start with AAanalysis) are titled by what they deliver, not a class.

Output / data-object names

The objects passed between steps have canonical names too — most are defined in the project glossary (CONTEXT.md). Use these consistently so a snippet reads the same everywhere; this table is a reference, not a test-enforced gate (only the class-instance names above are checked).

Canonical data-object variable names

Variable	Object (producer)
df_seq	sequence frame (load_dataset(), read_fasta())
df_scales / df_cat	AAontology scales / scale categories (load_scales(), build_cat)
df_parts	assembled parts (sf.get_df_parts)
split_kws	split specification (sf.get_split_kws) — matches the split_kws= parameter
df_feat	feature frame, canonical schema (cpp.run, load_features(), sm.add_*)
X / labels	feature matrix (sf.feature_matrix) / class labels (df_seq["label"].to_list())
df_eval	evaluation results (cpp/tm/dpul/aam/seqm .eval(...))
df_pos / feat_importance	feature positions (sf.get_df_pos) / importance column (tm.add_feat_importance)
df_logo / df_logo_info	sequence-logo frames (aal.get_df_logo / get_df_logo_info)
df_impact / df_scan	mutation impact (aam.run) / scan (seqm.scan)
df_pu / dict_num / df_annot / df_params	PU frame (dpul) / numerical parts (nf) / annotations (annp) / grid params (cppg)

Qualifiers belong on the data level. A variant of a data object takes a <name>_<qualifier> suffix (df_feat_res, X_res, df_cat_selected, df_top15) — used only when you actually have a variant, not stamped onto every example. Class instances stay the bare abbreviation (see above).

Keyword-dict (_kws) parameters

A *_kws parameter groups several related keyword arguments into one dict. There are two kinds, and the forwarded kind splits into two subtypes:

• forwarded — passed through (mostly) verbatim to another callable, so it accepts whatever that callable accepts (open-ended keys):

  • external — the target is a third-party library (e.g. Matplotlib);

  • internal — the target is another AAanalysis function or method.

• structured bundle — a fixed, documented key set consumed inside AAanalysis (validate unknown keys, default the unset ones).

Name any new one <noun>_kws and add it to the table below.

Keyword-dict (_kws) parameters

Parameter	Kind	Contents / target
cbar_kws	forwarded, external	Arbitrary keys for matplotlib.figure.Figure.colorbar().
legend_kws	forwarded, internal	Arbitrary keys for plot_legend().
feature_map_kws	forwarded, internal	Arbitrary keys for feature_map() (from CPPStructurePlot).
aal_kws / list_aal_kws	forwarded, internal	Keys for get_df_logo() / get_df_logo_info (list_ = one dict per logo).
df_parts_kws	forwarded, internal	Keys for sf.get_df_parts (e.g. list_parts, jmd_n_len) when building df_parts.
split_kws	structured bundle	One param-dict per split type: Segment (n_split_min, n_split_max), Pattern (steps, n_min, n_max, len_max), PeriodicPattern (steps). From sf.get_split_kws.
bootstrap_kws	structured bundle	Fixed keys rounds / resample / frac (any subset; unset keys keep their default) — CPP() bootstrap configuration.
sample_kws	structured bundle	Fixed keys sample (an entry name or name-column value str, or a row-position int), df_seq and df_parts — selects one sample for feature_map() / heatmap() / profile(), resolving its TMD-JMD sequence (and per-sample feat_impact column) from df_parts. The bundled alternative to passing tmd_seq / jmd_n_seq / jmd_c_seq directly.

Label parameter names

Each labeling concept has one canonical parameter name, used consistently across the classes a user combines in one workflow. Several names look similar but name different concepts — keep them distinct rather than collapsing them.

Canonical label parameter names

Concept	Canonical name	Notes
Contrast markers (the two groups being compared)	label_test / label_ref	The positive/test group vs the reference group of a contrast — run() / eval(), get_df_logo().
Single labeling (1D)	labels	One per-sample class-label vector, shape (n_samples,) — e.g. run(), fit() / eval, fit(), fit().
List of labelings (2D, multi-dataset)	list_labels	Several labelings stacked, shape (n_datasets, n_samples), paired with names_datasets — eval(), eval(). Distinct from labels on purpose: the plural marks a list of datasets, not one.
Target-class selector (a single class to attribute)	label_target_class	fit() — the one class whose model prediction the SHAP values explain. It can be any class (the positive, the negative/reference, or any index in a multi-class model), so it is not the same concept as label_test and deliberately keeps its own name.

Examples & verification

• Examples are authored as notebooks under examples/<subpackage>/ and pulled in with .. include:: examples/<name>.rst (converted at docs-build time).

• Keep them small, seeded, and deterministic. Example notebooks and tutorials are executed in CI (pytest --nbmake examples/ tutorials/) so they cannot rot; tiny self-contained snippets may additionally use >>> doctests run with --doctest-modules.

• Commit notebooks with their executed outputs. The docs render the stored cell outputs (nbsphinx_execute = 'never' in conf.py), and create_notebooks_docs.py converts each notebook to .rst from those saved outputs. A cell with no saved output renders no figure or table on Read the Docs — even though the blocking CI (which only checks that cells run) stays green, so the gap is invisible until you look at the built page. After editing any example/tutorial cell (including programmatic NotebookEdit, which clears the cell’s outputs), re-run the whole notebook and save it with outputs, e.g. jupyter nbconvert --to notebook --execute --inplace examples/<subpackage>/<name>.ipynb, then confirm the figures are embedded before committing.

Notebook content & structure

An example notebook teaches the symbol, it does not merely call it. Use this order:

1. Concept first (opening markdown cell). In natural prose before any code, explain what the method/class does, when and why to use it, and what it returns. Write it as flowing text — do not prefix the paragraphs with bold rhetorical labels (**Mental model.**, **When to use.**, **What it returns.**); state the content directly.

2. Minimal example (code cell). The smallest seeded, runnable call, with output.

3. Parameter walkthrough (markdown + code). Introduce every public parameter, with one cell per parameter group: parameters that belong together share a cell (e.g. jmd_n_len / jmd_c_len, or a family of max_* thresholds). Each group gets a short markdown note (what it controls) and a code cell showing its effect on the result. No parameter may be left uncovered.

4. Show output so the docs render it; keep every cell small, seeded, deterministic. The notebook must be committed with its executed outputs (figures + tables) — see Examples & verification above.

Glossary cross-links

Domain terms (df_seq, dict_num, pseudo-scale, entry, …) are defined once in a Sphinx .. glossary:: (sourced from the project glossary) and referenced from docstrings via :term:`dict_num` so a reader can click through to the canonical definition.

Math

Render formulas with .. math:: (or inline :math:`...`) rather than ASCII, e.g. in the metrics functions (AUC*, BIC, KLD).

Prose & punctuation

Keep punctuation plain across all documentation (docstrings and .rst pages), not only this guide.

• Avoid em dashes (``—``). They read as a tic when overused. Prefer a colon to introduce a label, list, or elaboration (**Overview**: New to AAanalysis ..., four sections: ...) and a comma for an aside or appositive (... signatures, the features that distinguish ...).

• Reserve the em dash for the rare genuine break in thought; never use it as a default connector or as bullet-label punctuation.

Conformance checklist

A docstring is house-style if every applicable item holds. The right column is the code emitted by the internal checker. The checker separates defects (hard violations — the run fails only on these) from advisory notes (CLASS-NO-CITATION — never fails, since utility classes legitimately omit a citation), and skips UNDER CONSTRUCTION stubs entirely (a class whose summary starts UNDER CONSTRUCTION, or a method whose body is just raise NotImplementedError). 0 defect(s) therefore means the convention is satisfied for every implemented public symbol.

Rule	Checker code
Class summary is a noun phrase (not a verb)	CLASS-SUMMARY-VERB
Class summary ends with a [Key]_ citation when a matching reference exists (advisory)	CLASS-NO-CITATION
Every [Key]_ is defined in references.rst (no typo’d / invented keys)	CITATION-UNDEFINED
.. versionadded:: present	NO-VERSIONADDED
Parameters in __init__, not the class docstring	CLASS-HAS-PARAMETERS
__init__ has a docstring	INIT-NO-DOCSTRING
Public symbol has a docstring	MISSING-DOCSTRING
Method summary has no arrow shorthand	SUMMARY-ARROW
Returns is named (name : type)	RETURNS-UNNAMED
Public method ends with an Examples include	METHOD-NO-EXAMPLES
Recurring params reuse the baseline sentence	DFSEQ-BASELINE
Citations use [Key]_ only	INLINE-CITATION / FREETEXT-CITATION
See Also entries are role bullets	SEEALSO-NO-BULLET
See Also gloss uses colon-space, not space-colon-space	SEEALSO-SPACE-COLON
Warnings header (not Warns)	WARNS-SECTION
Notes list items use * not -	NOTES-DASH-BULLET
Every [Key]_ is defined in references.rst	CITATION-UNDEFINED
:class:/:meth:/:func: targets resolve to a real public symbol	XREF-UNRESOLVED
A body that raises documents a Raises section (advisory)	RAISES-UNDOCUMENTED
Summary is followed by a plain-language description (advisory)	SUMMARY-ONLY

The build itself is the final gate: cd docs && make html (ideally with SPHINXOPTS="-W") must finish without warnings — broken section underlines, inline-literal RST errors, and unresolved .. include:: targets surface only there, not in the structural checker.

Tooling

# audit the whole package (or a single file)
python .claude/skills/docstrings/scripts/check_docstrings.py aaanalysis/
# auto-fix the safe mechanical drift (Warns→Warnings, See-Also colon spacing)
python .claude/skills/docstrings/scripts/check_docstrings.py --fix aaanalysis/

--fix applies only the mechanical subset; every other finding is an author-side fix against the templates above.

API reference order

The API reference (docs/source/api.rst) is ordered to read as the analysis pipeline, not alphabetically. A newly integrated public symbol must be slotted in by these rules:

1. Sections follow the workflow: Data Handling → Sequence Analysis → Feature Engineering → PU Learning → Explainable AI → Prediction → Protein Engineering → Utility Functions (data in → analyse → engineer features → model → predict → design → helpers).

2. Within a section, follow data flow: inputs/loaders first, then the processing classes, then combiners/outputs (Data Handling = loaders → preprocessors → combine_dict_nums()).

3. Parallel-modality families go sequence → structure → embedding → annotation (the sequence-to-structure-to-function logic), e.g. the preprocessors: SequencePreprocessor, StructurePreprocessor, EmbeddingPreprocessor, AnnotationPreprocessor.

4. A logic class is immediately followed by its ``*Plot`` pair, and close variants form one contiguous family: AAclust → AAclustPlot; the CPP family CPP → CPPGrid → CPPPlot; dPULearn → dPULearnPlot.

5. Core before pro where modality does not dictate otherwise (TreeModel before ShapModel).

6. Group functions by kind in Utility Functions: the comp_* metrics together, then display/options, then the plot_* helpers.

7. Every public symbol appears in ``api.rst`` exactly once — __all__ (incl. the commented pro entries) and api.rst must match. The checker’s API-INDEX-MISSING / API-INDEX-STALE enforces this coverage; placement within the section (rules 1–6) is a human call.