Use the Remote Data Manager

Often, data prep or analysis functions require files to be downloaded from a remote server. The remote data manager handles the usage of remote data files including file verification using hashes. For example, say a function, test_function, requires the remote data file: predicted-sunspot-radio-flux.txt, which has the SHA256 hash “4c85b04a5528aa97eb84a087450eda0421c71833820576330bba148564089b11”. To ensure that this exact version of the file is downloaded when test_function is called, use the require decorator.

>>> from sunpy.data import manager

>>> @manager.require('test_file',
...                  ['http://data.sunpy.org/sample-data/predicted-sunspot-radio-flux.txt'],
...                  '4c85b04a5528aa97eb84a087450eda0421c71833820576330bba148564089b11')
... def test_function():
...     pass

The first time the function is called, the file will be downloaded and then cached such that subsequent function calls will not trigger a download.

>>> test_function()  # The file will be downloaded  
>>> test_function()  # No download  

To access the downloaded file inside the function, use the get() method,

>>> @manager.require('test_file',
...                  ['http://data.sunpy.org/sample-data/predicted-sunspot-radio-flux.txt'],
...                  '4c85b04a5528aa97eb84a087450eda0421c71833820576330bba148564089b11')
... def test_function():
...     return manager.get('test_file')

To call a function that uses the data manager, but skip the hash check, use the skip_hash_check context manager.

>>> with manager.skip_hash_check():
...     test_function()  
PosixPath('.../sunpy/data_manager/predicted-sunspot-radio-flux.txt')

To replace the required file with another version, use the override_file context manager.

>>> with manager.override_file('test_file', 'http://data.sunpy.org/sample-data/AIA20110319_105400_0171.fits'):
...     test_function()  
PosixPath('.../sunpy/data_manager/AIA20110319_105400_0171.fits')