Analysis Plugins

Since SCT v3.2.0, analysis implementations live in external Python packages and are discovered at runtime through the sct.analyses entry point namespace. Each analysis plugin is a standalone installable package that implements the sct.plugins.protocols.AnalysisPluginProtocol.

Analyses Plugins — Schematics of the quality analysis plugin architecture.

Protocol

The plugin class must satisfy AnalysisPluginProtocol which requires:

AnalysisPluginProtocol (simplified)

class AnalysisPluginProtocol(Protocol):
    version: str
    short_help: str

    @classmethod
    def get_cli(cls) -> Typer | Callable: ...
    @classmethod
    def get_handlers(cls) -> dict[str, AnalysisHandler]: ...

version — package version, typically imported from __init__.
short_help — one‑line description shown in the sct --help output.
get_cli() — returns a Typer command or callable (or None).
get_handlers() — returns a dictionary mapping analysis type names to AnalysisHandler instances.

Analysis Handler

Each handler bundles three concerns using the sct.core.base.AnalysisHandler dataclass:

Python

@dataclass
class AnalysisHandler:
    config: Any                                          # AnalysisConfigABC subclass
    cli: Typer | Callable | None                         # CLI command
    testing: AnalysisTestingHandler | None               # testing hooks
    cli_group_name: str | None = None                    # optional group name

A single plugin may expose more than one handler (e.g., radiometry exposes nesz, rain-forest, profiles and scalloping under a shared cli_group_name="radiometry").

Entry Point Registration

Plugins declare themselves in pyproject.toml under the sct.analyses namespace:

TOML

[project.entry-points."sct.analyses"]
<analysis_name> = "sct_<analysis_name>_analysis.interface:<AnalysisName>AnalysisPlugin"

Discovery and CLI Integration

SCT uses two mechanisms to load analysis plugins:

CLI lazy loading — at startup, importlib.metadata.entry_points() scans the sct.analyses namespace. Only the lightweight interface.py module is imported. The actual CLI command is loaded only when the user invokes the subcommand.
Analysis registry — when programmatic access is needed, stevedore loads all plugins and calls get_handlers() to populate the global ANALYSIS_REGISTRY via register_analysis().

Available Analysis Plugins

The following analysis plugins are installed along SCT when installing the software with the [recommended] extra:

Analysis	Package	CLI Command
Point Target	`sct-point-target-analysis`	`sct point_target`
Radiometry	`sct-radiometric-analysis`	`sct radiometry` (group)
Spectra	`sct-spectral-analysis`	`sct spectra`
Elevation Notch	`sct-notch-analysis`	`sct elevation_notch`
Interferometry	`sct-interferometric-analysis`	`sct interferometry`
Ambiguity Ratio	`sct-ambiguities-analysis`	`sct ambiguities`

Refer to the plugins documentation site for detailed documentation of each analysis plugin, including usage, configuration and API references.

Installation and Usage

To install the default set of analysis plugins using pip, refer to the installation guide.

To install a specific plugin for SCT using pip:

Installing a Plugin

pip install <sct_analysis_plugin_name>

Then the software can discover automatically all the installed plugins and perform analyses on products corresponding to the installed plugins.

Creating a New Analysis Plugin

For a step-by-step guide on developing and packaging a new analysis plugin, refer to the developer guide.