Source code for opendrift.readers


Readers are responsible for providing Opendrift with data about the
`enviornment` of the drifting particles or elements.

All readers descend from :class:`.basereader.BaseReader`. A reader generally also descends from one of the few general classes of readers. When writing a new reader consider which one fits your input data best:

    * :class:`.basereader.continuous.ContinuousReader`
    * :class:`.basereader.structured.StructuredReader`
    * :class:`.basereader.unstructured.UnstructuredReader`

The `ContinuousReader` is suited for data that can be defined at any point within the domain, or if the reader does its own interpolation internally. E.g. a :class:`synthetic eddy <.reader_ArtificialOceanEddy.Reader>`, or a :class:`constant <.reader_constant.Reader>`. The `StructuredReader` aids in interpolation when creating a reader of data on a :class:`regular grid <.reader_netCDF_CF_generic.Reader>`, while the `UnstructuredReader` provides the basics for :class:`irregularily gridded data <.reader_netCDF_CF_unstructured.Reader>` (e.g. finite volume models).

.. seealso::

    See the reader-types or reader-implementations for more details.

    See :class:`.basereader.BaseReader` for how readers work internally.

import importlib
import logging; logger = logging.getLogger(__name__)
import glob
import json
import opendrift

[docs]def reader_from_url(url, timeout=10): '''Make readers from URLs or paths to datasets''' if isinstance(url, list): return [reader_from_url(u) for u in url] try: # Initialise reader from JSON string j = json.loads(url) try: reader_module = importlib.import_module( 'opendrift.readers.' + j['reader']) reader = getattr(reader_module, 'Reader') del j['reader'] reader = reader(**j) return reader except Exception as e: logger.warning('Creating reader from JSON failed:') logger.warning(e) except: pass if len(glob.glob(url)) == 0: # Check if this is a URL, and not giving timeout import requests try: resp = requests.get(url, timeout=timeout) except requests.exceptions.MissingSchema:'Neither a file or a URL: ' + url) return None except:'Connection error for ' + url) return None reader_modules = ['reader_netCDF_CF_generic', 'reader_ROMS_native', 'reader_grib'] for rm in reader_modules: reader_module = importlib.import_module('opendrift.readers.' + rm) try: r = reader_module.Reader(url) return r except Exception as e: print('Could not open %s with %s' % (url, rm)) return None # No readers worked