pcxarray.cache module

pcxarray.cache.cache(func=None, *cache_args, **cache_kwargs)

Cache the output of a function to disk using joblib.Memory.

This decorator can be used in two ways: 1. As @cache to cache the output of a function with default settings. 2. As @cache(...options...) to pass arguments to joblib.Memory.cache, such as cache validation callbacks.

The cache is stored in a platform-appropriate directory and helps avoid repeated expensive operations like downloading data.

Parameters:

  • func (callable, optional) – The function to be cached. If not provided, the decorator returns a wrapper that accepts a function.

  • *cache_args – Additional positional arguments passed to joblib.Memory.cache.

  • **cache_kwargs – Additional keyword arguments passed to joblib.Memory.cache.

Returns:

A decorator or decorated function that caches the output to disk.

Return type:

function

Examples

Use with default settings:

@cache
def my_function(...):
    ...

Use with custom cache options:

@cache(cache_validation_callback=expires_after(minutes=15))
def my_function(...):
    ...
pcxarray.cache.get_cache_dir()

Get or create a cache directory for pcxarray.

The cache directory is platform-dependent and is created if it does not exist. On Unix-like systems, it defaults to ~/.cache/pcxarray or $XDG_CACHE_HOME/pcxarray. On Windows, it uses %LOCALAPPDATA%/pcxarray or the system temp directory as fallback. The cache directory is used by joblib.Memory to store persistent function call results, particularly for expensive operations like downloading Census shapefiles.

Returns:

Absolute path to the cache directory on disk.

Return type:

str