Dependencies#

Types of dependencies#

There are three types of dependencies in sktime: * “core” dependencies * “soft” dependencies * “developer” dependencies

Note

A core dependency is required for sktime to install and run. They are automatically installed whenever sktime is installed. Example: pandas

Note

A soft dependency is a dependency that is only required to import certain modules, but not necessary to use most functionality. A soft dependency is not installed automatically when the package is installed. Instead, users need to install it manually if they want to use a module that requires a soft dependency. Example: pmdarima

Note

A developer dependency is required for sktime developers, but not for typical users of sktime. Example: pytest

We try to keep the number of core dependencies to a minimum and rely on other packages as soft dependencies when feasible.

Adding a soft dependency#

Soft dependencies in sktime should usually be restricted to estimators.

When adding a new soft dependency or changing the version of an existing one, the following files need to be updated:

  • pyproject.toml, adding the dependency or version bounds in the all_extras dependency set. Following the PEP 621 convention, all dependencies including build time dependencies and optional dependencies are specified in this file.

  • check_soft_dependencies.py, the dependency needs to be added together with the module that depends on it. We use continuous integration tests to check if all soft dependencies are properly isolated to specific modules.

Informative warnings or error messages for missing soft dependencies should be raised, in a situation where a user would need them. This is handled through our _check_soft_dependencies utility here.

There are specific conventions to add such warnings in estimators, as below. To add an estimator with a soft dependency, ensure the following:

  • imports of the soft dependency only happen inside the estimator, e.g., in _fit or __init__ methods of the estimator.

  • Errors and warnings, with informative instructions on how to install the soft dependency, are raised through _check_soft_dependencies here. In the python module containing the estimator, the function should be called twice: at the top of the module, with severity="warning". This will warn the user whenever they import the file and the soft dependency is not installed; and, at the beginning of __init__, with severity="error". This will raise an exception whenever the user attempts to instantiate the estimator, and the soft dependency is not installed.

  • ensure the module containing the estimator is registered here. This allows continuous integration tests to check if all soft dependencies are properly isolated to specific modules.

Adding a core or developer dependency#

Core or developer dependencies can be added only by core developers after discussion in the core developer meeting.

When adding a new core dependency or changing the version of an existing one, the following files need to be updated:

  • pyproject.toml, adding the dependency or version bounds in the dependencies dependency set.

When adding a new developer dependency or changing the version of an existing one, the following files need to be updated:

  • pyproject.toml, adding the dependency or version bounds in the dev dependency set.