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OGC Coverages: add CoverageScaling class
This is a helper class for implementing coverage scaling operations. Not yet fully implemented and not yet in use.
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| import unittest | ||
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| import pyproj | ||
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| import xcube.core.new | ||
| from xcube.server.api import ApiError | ||
| from xcube.webapi.ows.coverages.request import CoveragesRequest | ||
| from xcube.webapi.ows.coverages.scaling import CoverageScaling | ||
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| class ScalingTest(unittest.TestCase): | ||
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| def setUp(self): | ||
| self.epsg4326 = pyproj.CRS('EPSG:4326') | ||
| self.ds = xcube.core.new.new_cube() | ||
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| def test_default_scaling(self): | ||
| scaling = CoverageScaling(CoveragesRequest({}), self.epsg4326, self.ds) | ||
| self.assertEqual((1, 1), scaling.scale) | ||
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| def test_no_data(self): | ||
| with self.assertRaises(ApiError.NotFound): | ||
| CoverageScaling( | ||
| CoveragesRequest({}), self.epsg4326, | ||
| self.ds.isel(lat=slice(0, 0)) | ||
| ) | ||
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| def test_crs_fallbacks(self): | ||
| # TODO: implement me | ||
| pass | ||
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| def test_scale_factor(self): | ||
| scaling = CoverageScaling( | ||
| CoveragesRequest({'scale-factor': ['2']}), | ||
| self.epsg4326, | ||
| self.ds | ||
| ) | ||
| self.assertEqual((2, 2), scaling.scale) | ||
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| def test_scale_axes(self): | ||
| scaling = CoverageScaling( | ||
| CoveragesRequest({'scale-axes': ['Lat(3),Lon(1.2)']}), | ||
| self.epsg4326, | ||
| self.ds | ||
| ) | ||
| self.assertEqual((1.2, 3), scaling.scale) | ||
| self.assertEqual((300, 60), scaling.size) | ||
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| def test_scale_size(self): | ||
| scaling = CoverageScaling( | ||
| CoveragesRequest({'scale-size': ['Lat(90),Lon(240)']}), | ||
| self.epsg4326, | ||
| self.ds | ||
| ) | ||
| self.assertEqual((240, 90), scaling.size) | ||
| self.assertEqual((1.5, 2), scaling.scale) |
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| # The MIT License (MIT) | ||
| # Copyright (c) 2023 by the xcube team and contributors | ||
| # | ||
| # Permission is hereby granted, free of charge, to any person obtaining a | ||
| # copy of this software and associated documentation files (the "Software"), | ||
| # to deal in the Software without restriction, including without limitation | ||
| # the rights to use, copy, modify, merge, publish, distribute, sublicense, | ||
| # and/or sell copies of the Software, and to permit persons to whom the | ||
| # Software is furnished to do so, subject to the following conditions: | ||
| # | ||
| # The above copyright notice and this permission notice shall be included in | ||
| # all copies or substantial portions of the Software. | ||
| # | ||
| # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | ||
| # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | ||
| # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | ||
| # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | ||
| # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | ||
| # FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER | ||
| # DEALINGS IN THE SOFTWARE. | ||
| from typing import Optional | ||
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| import pyproj | ||
| import xarray as xr | ||
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| from xcube.server.api import ApiError | ||
| from xcube.webapi.ows.coverages.controllers import get_h_dim, get_v_dim | ||
| from xcube.webapi.ows.coverages.request import CoveragesRequest | ||
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| class CoverageScaling: | ||
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| _scale: Optional[tuple[float, float]] = None | ||
| _final_size: Optional[tuple[int, int]] = None | ||
| _initial_size: tuple[int, int] | ||
| _crs: pyproj.CRS | ||
| _x_name: str | ||
| _y_name: str | ||
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| def __init__(self, request: CoveragesRequest, crs: pyproj.CRS, | ||
| ds: xr.Dataset): | ||
| h_dim = get_h_dim(ds) | ||
| v_dim = get_v_dim(ds) | ||
| for d in h_dim, v_dim: | ||
| size = ds.dims[d] | ||
| if size == 0: | ||
| # Requirement 8C currently specifies a 204 rather than 404 here, | ||
| # but spec will soon be updated to allow 404 as an alternative. | ||
| # (J. Jacovella-St-Louis, pers. comm., 2023-11-27). | ||
| raise ApiError.NotFound( | ||
| f'Requested coverage contains no data: {d} has zero size.' | ||
| ) | ||
| self._initial_size = ds.dims[h_dim], ds.dims[v_dim] | ||
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| self._crs = crs | ||
| self._y_name = self.get_axis_from_crs( | ||
| {'lat', 'latitude', 'geodetic latitude', 'n', 'north', 'y'} | ||
| ) | ||
| self._x_name = self.get_axis_from_crs( | ||
| {'longitude', 'geodetic longitude', 'lon', 'e', 'east', 'x'} | ||
| ) | ||
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| # The standard doesn't define behaviour when multiple scale | ||
| # parameters are given. We choose to handle one and ignore the | ||
| # others in such cases. | ||
| if request.scale_factor is not None: | ||
| self._scale = request.scale_factor, request.scale_factor | ||
| elif request.scale_axes is not None: | ||
| self._scale = self._get_xy_values(request.scale_axes) | ||
| elif request.scale_size is not None: | ||
| # The standard allows floats for "scale-size" but mandates: | ||
| # "The returned coverage SHALL contain exactly the specified number | ||
| # of sample values". We can't return a fractional number of sample | ||
| # values, so truncate to int here. | ||
| x, y = self._get_xy_values(request.scale_size) | ||
| self._final_size = int(x), int(y) | ||
| else: | ||
| # The standard doesn't mandate this as a default; in future, we | ||
| # might choose to downscale automatically if a large coverage | ||
| # is requested without an explicit scaling parameter. | ||
| self._scale = (1, 1) | ||
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| @property | ||
| def scale(self) -> tuple[float, float]: | ||
| if self._scale is not None: | ||
| return self._scale | ||
| else: | ||
| x_initial, y_initial = self._initial_size | ||
| x_final, y_final = self._final_size | ||
| return x_initial / x_final, y_initial / y_final | ||
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| @property | ||
| def size(self) -> tuple[float, float]: | ||
| if self._final_size is not None: | ||
| return self._final_size | ||
| else: | ||
| x_initial, y_initial = self._initial_size | ||
| x_scale, y_scale = self._scale | ||
| return x_initial / x_scale, y_initial / y_scale | ||
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| def _get_xy_values( | ||
| self, axis_to_value: dict[str, float] | ||
| ) -> tuple[float, float]: | ||
| x, y = None, None | ||
| for axis in axis_to_value: | ||
| if axis.lower()[:3] in ['x', 'e', 'eas', 'lon', self._x_name]: | ||
| x = axis_to_value[axis] | ||
| if axis.lower()[:3] in ['y', 'n', 'nor', 'lat', self._y_name]: | ||
| y = axis_to_value[axis] | ||
| return x, y | ||
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| def get_axis_from_crs(self, valid_identifiers: set[str]): | ||
| for axis in self._crs.axis_info: | ||
| if not hasattr(axis, 'abbrev'): | ||
| continue | ||
| identifiers = set(map( | ||
| lambda attr: getattr(axis, attr, '').lower(), | ||
| ['name', 'abbrev'] | ||
| )) | ||
| if identifiers & valid_identifiers: | ||
| return axis.abbrev | ||
| return None | ||