SciPy API#

Importing from SciPy#

In Python, the distinction between what is the public API of a library and what are private implementation details is not always clear. Unlike in other languages like Java, it is possible in Python to access “private” functions or objects. Occasionally this may be convenient, but be aware that if you do so your code may break without warning in future releases. Some widely understood rules for what is and isn’t public in Python are:

  • Methods / functions / classes and module attributes whose names begin with a leading underscore are private.

  • If a class name begins with a leading underscore, none of its members are public, whether or not they begin with a leading underscore.

  • If a module name in a package begins with a leading underscore none of its members are public, whether or not they begin with a leading underscore.

  • If a module or package defines __all__, that authoritatively defines the public interface.

  • If a module or package doesn’t define __all__, then all names that don’t start with a leading underscore are public.

Note

Reading the above guidelines one could draw the conclusion that every private module or object starts with an underscore. This is not the case; the presence of underscores do mark something as private, but the absence of underscores do not mark something as public.

In SciPy there are modules whose names don’t start with an underscore, but that should be considered private. To clarify which modules these are, we define below what the public API is for SciPy, and give some recommendations for how to import modules/functions/objects from SciPy.

Guidelines for importing functions from SciPy#

Everything in the namespaces of SciPy submodules is public. In general in Python, it is recommended to make use of namespaces. For example, the function curve_fit (defined in scipy/optimize/_minpack_py.py) should be imported like this:

import scipy
result = scipy.optimize.curve_fit(...)

Or alternatively one could use the submodule as a namespace like so:

from scipy import optimize
result = optimize.curve_fit(...)

Note

For scipy.io prefer the use of import scipy because io is also the name of a module in the Python stdlib.

In some cases, the public API is one level deeper. For example, the scipy.sparse.linalg module is public, and the functions it contains are not available in the scipy.sparse namespace. Sometimes it may result in more easily understandable code if functions are imported from one level deeper. For example, in the following it is immediately clear that lomax is a distribution if the second form is chosen:

# first form
from scipy import stats
stats.lomax(...)

# second form
from scipy.stats import distributions
distributions.lomax(...)

In that case, the second form can be chosen if it is documented in the next section that the submodule in question is public. Of course you can still use:

import scipy
scipy.stats.lomax(...)
# or
scipy.stats.distributions.lomax(...)

Note

SciPy is using a lazy loading mechanism which means that modules are only loaded in memory when you first try to access them.

API definition#

Every submodule listed below is public. That means that these submodules are unlikely to be renamed or changed in an incompatible way, and if that is necessary, a deprecation warning will be raised for one SciPy release before the change is made.

SciPy structure#

All SciPy modules should follow the following conventions. In the following, a SciPy module is defined as a Python package, say yyy, that is located in the scipy/ directory.

  • Ideally, each SciPy module should be as self-contained as possible. That is, it should have minimal dependencies on other packages or modules. Even dependencies on other SciPy modules should be kept to a minimum. A dependency on NumPy is of course assumed.

  • Directory yyy/ contains:

    • A file meson.build with build configuration for the submodule.

    • A directory tests/ that contains files test_<name>.py corresponding to modules yyy/<name>{.py,.so,/}.

  • Private modules should be prefixed with an underscore _, for instance yyy/_somemodule.py.

  • User-visible functions should have good documentation following the NumPy documentation style.

  • The __init__.py of the module should contain the main reference documentation in its docstring. This is connected to the Sphinx documentation under doc/ via Sphinx’s automodule directive.

    The reference documentation should first give a categorized list of the contents of the module using autosummary:: directives, and after that explain points essential for understanding the use of the module.

    Tutorial-style documentation with extensive examples should be separate and put under doc/source/tutorial/.

See the existing SciPy submodules for guidance.

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