Utilities for working with the local dataset cache.


cached_path(url_or_filename:Union[str, pathlib.Path], cache_dir:str=None) -> str

Given something that might be a URL (or might be a local path), determine which. If it's a URL, download the file and cache it, and return the path to the cached file. If it's already a local path, make sure the file exists and then return the path.


filename_to_url(filename:str, cache_dir:str=None) -> Tuple[str, str]

Return the url and etag (which may be None) stored for filename. Raise FileNotFoundError if filename or its stored metadata do not exist.


get_from_cache(url:str, cache_dir:str=None) -> str

Given a URL, look for the corresponding dataset in the local cache. If it's not there, download it. Then return the path to the cached file.


    url_or_filename: Optional[str, pathlib.Path],
) -> bool

Given something that might be a URL (or might be a local path), determine check if it's url or an existing file path.


read_set_from_file(filename:str) -> Set[str]

Extract a de-duped collection (set) of text from a file. Expected file format is one item per line.


s3_etag(url:str) -> Union[str, NoneType]

Check ETag on S3 object.


s3_get(url:str, temp_file:IO) -> None

Pull a file directly from S3.



Wrapper function for s3 requests in order to create more helpful error messages.


session_with_backoff() -> requests.sessions.Session

We ran into an issue where http requests to s3 were timing out, possibly because we were making too many requests too quickly. This helper function returns a requests session that has retry-with-backoff built in. see


split_s3_path(url:str) -> Tuple[str, str]

Split a full s3 path into the bucket name and path.


url_to_filename(url:str, etag:str=None) -> str

Convert url into a hashed filename in a repeatable way. If etag is specified, append its hash to the url's, delimited by a period.