yatsm.cache module

Functions related to writing to and retrieving from cache files

yatsm.cache.get_line_cache_name(dataset_config, n_images, row, nbands)

Returns cache filename for specified config and line number

Parameters:

• dataset_config – configuration information about the dataset
• n_images – number of images in dataset
• row – line of the dataset for output
• nbands – number of bands in dataset

Returns:

filename of cache file

Return type:

str

yatsm.cache.get_line_cache_pattern(row, nbands, regex=False)

Returns a pattern for a cache file from a certain row

This function is useful for finding all cache files from a line, ignoring the number of images in the file.

Parameters:

• row – line of the dataset for output
• nbands – number of bands in dataset
• regex – return a regular expression instead of glob style (default: False)

Returns:

filename pattern for cache files from line row

Return type:

str

yatsm.cache.read_cache_file(cache_filename, image_IDs=None)

Returns image data from a cache file

If image_IDs is not None this function will try to ensure data from cache file come from the list of image IDs provided. If cache file does not contain a list of image IDs, it will skip the check and return cache data.

Parameters:

• cache_filename – cache filename
• image_IDs – list of image IDs corresponding to data in cache file. If not specified, function will not check for correspondence (default: None)

Returns:

Return Y as np.ndarray if possible and if the

cache file passes the consistency check specified by image_IDs, else None

Return type:

np.ndarray, or None

yatsm.cache.test_cache(dataset_config)

Test cache directory for ability to read from or write to

Parameters:dataset_config – dictionary of dataset configuration options Returns:

tuple of bools describing ability to read from and write to

cache directory

Return type:tuple

yatsm.cache.update_cache_file(images, image_IDs, old_cache_filename, new_cache_filename, line, reader)

Modify an existing cache file to contain data within images

This should be useful for updating a set of cache files to reflect modifications to the timeseries dataset without completely reading the data into another cache file.

For example, the cache file could be updated to reflect the deletion of a misregistered or cloudy image. Another common example would be for updating cache files to include newly acquired observations.

Note that this updater will not handle updating cache files to include new bands.

Parameters:

• images – list of new image filenames
• image_IDs – list of new image identifying strings
• old_cache_filename – filename of cache file to update
• new_cache_filename – filename of new cache file which includes modified data
• line – the line of data to be updated
• reader – GDAL or BIP image reader function from yatsm.io.stack_line_readers

Raises:

ValueError – Raise error if old cache file does not record image_IDs

yatsm.cache.write_cache_file(cache_filename, Y, image_IDs)

Writes data to a cache file using np.savez_compressed

Parameters:

• cache_filename – cache filename
• Y – data to write to cache file
• image_IDs – list of image IDs corresponding to data in cache file. If not specified, function will not check for correspondence