Pandas Accessor Integration

pandas-accessor-integration

Summary

Integrate a custom visualization backend into Pandas DataFrames via the accessor pattern, enabling domain-specific plot kinds (spectrum, chromatogram, mobilogram, peakmap) to be called directly on DataFrame objects with a consistent API across multiple plotting backends (matplotlib, bokeh, plotly).

When to use

You have mass-spectrometry data in a Pandas DataFrame and need to expose plot kinds (spectrum, chromatogram, mobilogram, peakmap) as a .plot(kind='...') interface that routes to backend-specific rendering (matplotlib for static, bokeh or plotly for interactive) without requiring users to import backend-specific classes directly.

When NOT to use

• You are visualizing non-mass-spectrometry data; use standard pandas.plotting instead.
• You need custom plot kinds not in the supported set (spectrum, chromatogram, mobilogram, peakmap); extend the base classes first.
• Your data is already in a format other than Pandas DataFrame; convert to DataFrame first before using the accessor.

Inputs

• pandas.DataFrame with mass-spectrometry columns (m/z, intensity, retention time, mobility, etc.)
• kind parameter (string: 'spectrum', 'chromatogram', 'mobilogram', 'peakmap')
• backend parameter (string: 'matplotlib', 'bokeh', or 'plotly')
• x, y, z column names (strings)
• optional configuration object (SpectrumConfig, ChromatogramConfig, MobilogramConfig, PeakMapConfig)

Outputs

• plot object (matplotlib Figure, bokeh Figure, or plotly Figure)
• interactive or static visualization rendered to display or file

How to apply

Register a custom pandas accessor (e.g., @pd.api.extensions.register_dataframe_accessor('plot')) that intercepts the .plot(kind=...) call. Inside the accessor's __call__ or plot() method, implement a kind-dispatch mechanism that maps the kind argument ('spectrum', 'chromatogram', 'mobilogram', 'peakmap') to the appropriate concrete plot subclass (SpectrumPlot, ChromatogramPlot, MobilogramPlot, PeakMapPlot). Determine the backend from a user-supplied or default parameter (backend='matplotlib'|'bokeh'|'plotly'), then instantiate the corresponding backend-specific subclass (e.g., MATPLOTLIBSpectrumPlot, BOKEHSpectrumPlot) with x, y, and optional z column names and a configuration object (SpectrumConfig, ChromatogramConfig, etc.). Call the backend-specific generate() method to produce and return the plot object. This pattern allows users to write df.plot(x='m/z', y='intensity', kind='spectrum', backend='bokeh') without knowing the underlying class hierarchy.

Related tools

• Pandas (Provides the DataFrame object and accessor registration pattern; used for data manipulation and as the entry point for plot dispatch) — https://pandas.pydata.org
• matplotlib (Backend for static plot rendering; instantiated via MATPLOTLIBPlot and concrete subclasses (MATPLOTLIBSpectrumPlot, MATPLOTLIBChromatogramPlot, etc.))
• bokeh (Backend for interactive plot rendering; instantiated via BOKEHPlot and concrete subclasses (BOKEHSpectrumPlot, BOKEHChromatogramPlot, etc.))
• plotly (Backend for interactive plot rendering; instantiated via PLOTLYPlot and concrete subclasses (PLOTLYSpectrumPlot, PLOTLYChromatogramPlot, etc.))
• pyOpenMS-viz (Implements the accessor integration, class hierarchy, and kind-dispatch mechanism for mass-spectrometry visualization) — https://github.com/OpenMS/pyopenms_viz

Examples

ms_data.plot(x="m/z", y="intensity", kind="spectrum", backend="bokeh")

Evaluation signals

• Verify that df.plot(kind='spectrum') returns a plot object of the expected backend type without raising AttributeError or NotImplementedError.
• Confirm that the same DataFrame and parameters produce consistent output when backend is switched from 'matplotlib' to 'bokeh' or 'plotly' (same data mapped to x, y, z axes).
• Check that invalid kind values raise a clear ValueError identifying supported plot kinds.
• Validate that configuration objects (SpectrumConfig, ChromatogramConfig, etc.) are passed through to the backend-specific generate() method and reflected in plot styling (axes labels, colors, etc.).
• Ensure that the accessor does not conflict with pandas' native .plot() method by testing backward compatibility on standard plot kinds (line, scatter, bar).

Limitations

• The accessor pattern requires explicit registration and may conflict with other custom accessors on the same DataFrame class.
• All plot kinds must be predefined in the concrete subclass hierarchy; dynamic or ad-hoc plot kinds cannot be added via the accessor alone.
• Performance may degrade for very large DataFrames if data is not pre-filtered or aggregated before passing to the accessor.
• The accessor provides a unified API but backend-specific features (e.g., 3D plots in plotly but not bokeh for peakmap) may still require conditional logic or fallback behavior.

Evidence

• [other] Implement a kind-dispatch mechanism in the pandas plotting backend accessor that routes kind='spectrum', 'chromatogram', 'mobilogram', 'peakmap' to the appropriate concrete plot class constructor based on backend selection.: "Implement a kind-dispatch mechanism in the pandas plotting backend accessor that routes kind='spectrum', 'chromatogram', 'mobilogram', 'peakmap' to the appropriate concrete plot class constructor"
• [readme] pyOpenMS-Viz provides a simple interface for extending the plotting capabilities of Pandas DataFrames for creating static or interactive visualizations of mass spectrometry data.: "provides a simple interface for extending the plotting capabilities of Pandas DataFrames for creating static or interactive visualizations of mass spectrometry data"
• [readme] Flexible plotting API that interfaces directly with Pandas DataFrames; Support for multiple plotting backends: matplotlib (static), bokeh and plotly (interactive): "Flexible plotting API that interfaces directly with Pandas DataFrames; Support for multiple plotting backends: matplotlib (static), bokeh and plotly (interactive)"
• [readme] Consistent API across different plotting backends for easy switching between static and interactive plots: "Consistent API across different plotting backends for easy switching between static and interactive plots"
• [other] Plot directly from a pandas dataframe object: "Plot directly from a pandas dataframe object"