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Download protocols

Download protocols#

Pooch supports the HTTP, FTP, and SFTP protocols by default. It also includes a custom protocol for Digital Object Identifiers (DOI) from providers like figshare and Zenodo (see below). It will automatically detect the correct protocol from the URL and use the appropriate download method.

Note

To download files over SFTP, paramiko needs to be installed.

For example, if our data were hosted on an FTP server, we could use the following setup:

POOCH = pooch.create(
    path=pooch.os_cache("plumbus"),
    # Use an FTP server instead of HTTP. The rest is all the same.
    base_url="ftp://garage-basement.org/{version}/",
    version=version,
    version_dev="main",
    registry={
        "c137.csv": "19uheidhlkjdwhoiwuhc0uhcwljchw9ochwochw89dcgw9dcgwc",
        "cronen.csv": "1upodh2ioduhw9celdjhlfvhksgdwikdgcowjhcwoduchowjg8w",
    },
)


def fetch_c137():
    """
    Load the C-137 sample data as a pandas.DataFrame (over FTP this time).
    """
    fname = POOCH.fetch("c137.csv")
    data = pandas.read_csv(fname)
    return data

You can even specify custom functions for the download or login credentials for authentication. See Downloaders: Customizing the download for more information.

Digital Object Identifiers (DOIs)#

Pooch can download files stored in data repositories from the DOI by formatting the URL as doi:{DOI}/{file name}. Notice that there are no // like in HTTP/FTP and you must specify a file name after the DOI (separated by a /).

See also

For a list of supported data repositories, see pooch.DOIDownloader.

For example, one of our test files ("tiny-data.txt") is stored in the figshare dataset doi:10.6084/m9.figshare.14763051.v1. We can could use pooch.retrieve to download it like so:

file_path = pooch.retrieve(
    url="doi:10.6084/m9.figshare.14763051.v1/tiny-data.txt",
    known_hash="md5:70e2afd3fd7e336ae478b1e740a5f08e",
)

We can also make a pooch.Pooch with a registry stored entirely on a figshare dataset:

POOCH = pooch.create(
    path=pooch.os_cache("plumbus"),
    # Use the figshare DOI
    base_url="doi:10.6084/m9.figshare.14763051.v1/",
    registry={
        "tiny-data.txt": "md5:70e2afd3fd7e336ae478b1e740a5f08e",
        "store.zip": "md5:7008231125631739b64720d1526619ae",
    },
)


def fetch_tiny_data():
    """
    Load the tiny data as a numpy array.
    """
    fname = POOCH.fetch("tiny-data.txt")
    data = numpy.loadtxt(fname)
    return data

Warning

A figshare DOI must point to a figshare dataset, not a figshare collection. Collection DOIs have a .c. in them, e.g. doi:10.6084/m9.figshare.c.4362224.v1. Attempting to download files from a figshare collection will raise an error. See issue #274 details.

Since this type of repositories store information about the files contained in them, we can avoid having to manually type the registry with the file names and their hashes. Instead, we can use the pooch.Pooch.load_registry_from_doi to automatically populate the registry:

POOCH = pooch.create(
    path=pooch.os_cache("plumbus"),
    # Use the figshare DOI
    base_url="doi:10.6084/m9.figshare.14763051.v1/",
    registry=None,
)

# Automatically populate the registry
POOCH.load_registry_from_doi()

# Fetch one of the files in the repository
fname = POOCH.fetch("tiny-data.txt")
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