Coverage for python / lsst / images / _cell_grid.py: 44%
109 statements
« prev ^ index » next coverage.py v7.14.0, created at 2026-05-16 07:54 +0000
1# This file is part of lsst-images.
2#
3# Developed for the LSST Data Management System.
4# This product includes software developed by the LSST Project
5# (https://www.lsst.org).
6# See the COPYRIGHT file at the top-level directory of this distribution
7# for details of code ownership.
8#
9# Use of this source code is governed by a 3-clause BSD-style
10# license that can be found in the LICENSE file.
12from __future__ import annotations
14# This module is conceptually part of the 'cells' subpackage, but we don't
15# want the stuff in '_concrete_bounds' to depend on all of that. So the
16# basic CellGrid and CellGridBounds objects are defined here, used in both
17# places, and exported from 'cells'.
19__all__ = (
20 "CellGrid",
21 "CellGridBounds",
22 "CellIJ",
23 "PatchDefinition",
24)
26import dataclasses
27import math
28from collections.abc import Iterator
29from functools import cached_property
30from typing import TYPE_CHECKING, Any, overload
32import numpy as np
33import pydantic
35from ._geom import YX, Bounds, Box
37if TYPE_CHECKING:
38 try:
39 from lsst.cell_coadds import UniformGrid
40 from lsst.skymap import Index2D
41 except ImportError:
42 type UniformGrid = Any # type: ignore[no-redef]
43 type Index2D = Any # type: ignore[no-redef]
46@dataclasses.dataclass(frozen=True, order=True)
47class CellIJ:
48 """An index in a grid of cells.
50 Notes
51 -----
52 This is deliberately not a `tuple` or other `~collections.abc.Sequence` in
53 order to make it typing-incompatible with sequence-based pixel coordinate
54 pairs (e.g. `.YX`). This also allows it to have addition and subtraction
55 operators.
56 """
58 i: int
59 """The y / row object."""
61 j: int
62 """The x / column object."""
64 def __add__(self, other: CellIJ) -> CellIJ:
65 return CellIJ(i=self.i + other.i, j=self.j + other.j)
67 def __sub__(self, other: CellIJ) -> CellIJ:
68 return CellIJ(i=self.i - other.i, j=self.j - other.j)
70 @staticmethod
71 def from_legacy(legacy_index: Index2D) -> CellIJ:
72 """Convert from a legacy `lsst.skymap.Index2D` instance.
74 Notes
75 -----
76 `lsst.skymap.Index2D` is ordered ``(x, y)``, i.e. ``(j, i)``.
77 """
78 return CellIJ(i=legacy_index.y, j=legacy_index.x)
80 def to_legacy(self) -> Index2D:
81 """Convert to a legacy `lsst.skymap.Index2D` instance.
83 Notes
84 -----
85 `lsst.skymap.Index2D` is ordered ``(x, y)``, i.e. ``(j, i)``.
86 """
87 from lsst.skymap import Index2D
89 return Index2D(x=self.j, y=self.i)
92class CellGrid(pydantic.BaseModel, frozen=True):
93 """A grid of rectangular cells with no overlaps or space between cells.
95 Notes
96 -----
97 A cell grid usually corresponds to a full patch, but we do not explicitly
98 encode this in the type to permit full-tract grids, which would have to
99 drop the cells in patch overlap regions and re-label all cells.
101 Subsets of grids are usually represented via `CellGridBounds`.
102 """
104 bbox: Box = pydantic.Field(
105 description=(
106 "Bounding box of the grid of cells (snapped to cell boundaries. "
107 "The cell with index (i=0, j=0) always has a corner at ``(y=bbox.y.min, x=bbox.x.min)`` "
108 "but there is no expectation that ``(y=bbox.y.min, x=bbox.x.min)`` be ``(y=0, x=0)``."
109 )
110 )
111 cell_shape: YX[int] = pydantic.Field(description="Shape of each cell in pixels.")
113 @property
114 def grid_shape(self) -> CellIJ:
115 """The number of cells in each dimension (`CellIJ`)."""
116 return CellIJ(i=self.bbox.y.size // self.cell_shape.y, j=self.bbox.x.size // self.cell_shape.x)
118 def index_of(self, *, y: int, x: int) -> CellIJ:
119 """Return the 2-d index of the cell that contains the given pixel.
121 Parameters
122 ----------
123 y
124 Y cell index.
125 x
126 X cell index.
127 """
128 return CellIJ(
129 i=(y - self.bbox.y.start) // self.cell_shape.y,
130 j=(x - self.bbox.x.start) // self.cell_shape.x,
131 )
133 def bbox_of(self, cell: CellIJ) -> Box:
134 """Return the bounding box of the given cell."""
135 return Box.from_shape(
136 self.cell_shape,
137 start=YX(
138 y=cell.i * self.cell_shape.y + self.bbox.y.start,
139 x=cell.j * self.cell_shape.x + self.bbox.x.start,
140 ),
141 )
143 @staticmethod
144 def from_legacy(legacy: UniformGrid) -> CellGrid:
145 """Construct from a legacy grid object.
147 Parameters
148 ----------
149 legacy
150 Legacy grid to convert.
151 """
152 if legacy.padding:
153 raise ValueError("Only cell grids with no padding are supported.")
154 bbox = Box.from_legacy(legacy.bbox)
155 cell_shape = YX(y=legacy.cell_size.y, x=legacy.cell_size.x)
156 return CellGrid(bbox=bbox, cell_shape=cell_shape)
159class CellGridBounds(pydantic.BaseModel, frozen=True):
160 """A region of pixels defined by a set of cells within a grid.
162 Notes
163 -----
164 This data structure is optimized for the case where a continguous
165 rectangular region of the grid (the `bbox` attribute) is populated with
166 only a few exceptions (the `missing` set).
168 Slicing a `CellGridBounds` with a `.Box` returns a new `CellGridBounds`
169 with just the cells that overlap that box. As always,
170 `CellGridBounds.bbox` will be snapped to the outer boundaries of those
171 cells, so it will contain (and not generally equal) the given box.
172 """
174 grid: CellGrid = pydantic.Field(description="Definition of the grid that defines the cells.")
175 bbox: Box = pydantic.Field(description="Pixel bounding box of the region (snapped to cell boundaries).")
176 missing: frozenset[CellIJ] = pydantic.Field(
177 default=frozenset(),
178 description=(
179 "Indices of cells that are missing, where (i=0, j=0) is the cell that starts at grid.bbox.start."
180 ),
181 )
183 @cached_property
184 def grid_start(self) -> CellIJ:
185 """The index of the first cell in this bounds' bounding box within
186 its grid.
187 """
188 return self.grid.index_of(y=self.bbox.y.start, x=self.bbox.x.start)
190 @cached_property
191 def grid_stop(self) -> CellIJ:
192 """One-past-the-last indices for the cells in these bounds, within
193 its grid.
194 """
195 return self.grid.index_of(y=self.bbox.y.stop, x=self.bbox.x.stop)
197 @overload
198 def contains(self, *, x: int, y: int) -> bool: ... 198 ↛ exitline 198 didn't return from function 'contains' because
200 @overload
201 def contains(self, *, x: np.ndarray, y: np.ndarray) -> np.ndarray: ... 201 ↛ exitline 201 didn't return from function 'contains' because
203 def contains(self, *, x: Any, y: Any) -> Any:
204 """Test whether these bounds contain one or more points.
206 Parameters
207 ----------
208 x
209 One or more integer X coordinates to test for containment.
210 If an array, an array of results will be returned.
211 y
212 One or more integer Y coordinates to test for containment.
213 If an array, an array of results will be returned.
215 Returns
216 -------
217 `bool` | `numpy.ndarray`
218 If ``x`` and ``y`` are both scalars, a single `bool` value. If
219 ``x`` and ``y`` are arrays, a boolean array with their broadcasted
220 shape.
221 """
222 result = self.bbox.contains(x=x, y=y)
223 if not self.missing:
224 return result
225 match result:
226 case False:
227 return False
228 case True:
229 return self.grid.index_of(x=x, y=y) not in self.missing
230 case np.ndarray():
231 for box in self.missing_boxes():
232 result = np.logical_and(result, np.logical_not(box.contains(x=x, y=y)))
233 return result
235 def intersection(self, other: Bounds) -> Bounds:
236 """Compute the intersection of this bounds object with another."""
237 from ._concrete_bounds import _intersect_cgb
239 return _intersect_cgb(self, other)
241 def contains_cell(self, index: CellIJ) -> bool:
242 """Test whether the given cell is in the bounds."""
243 return (
244 (index.i >= self.grid_start.i and index.i < self.grid_stop.i)
245 and (index.j >= self.grid_start.j and index.j < self.grid_stop.j)
246 and index not in self.missing
247 )
249 def missing_boxes(self) -> Iterator[Box]:
250 """Iterate over the bounding boxes of the missing cells."""
251 for index in sorted(self.missing):
252 yield self.grid.bbox_of(index)
254 def cell_indices(self) -> Iterator[CellIJ]:
255 """Iterate over the indices of the cells in these bounds."""
256 for i in range(self.grid_start.i, self.grid_stop.i):
257 for j in range(self.grid_start.j, self.grid_stop.j):
258 index = CellIJ(i=i, j=j)
259 if index not in self.missing:
260 yield index
262 def __getitem__(self, bbox: Box) -> CellGridBounds:
263 if not self.bbox.contains(bbox):
264 raise ValueError(
265 f"Original grid bounding box {self.bbox} does not contain the subset bounding box {bbox}."
266 )
267 c = self.grid.cell_shape
268 s = self.grid.bbox.start
269 i1 = (bbox.y.start - s.y) // c.y
270 j1 = (bbox.x.start - s.x) // c.x
271 i2 = math.ceil((bbox.y.stop - s.y) / c.y)
272 j2 = math.ceil((bbox.x.stop - s.x) / c.x)
273 subset_bbox = Box.factory[i1 * c.y + s.y : i2 * c.y + s.y, j1 * c.x + s.x : j2 * c.x + s.x]
274 grid_as_box = Box.factory[i1:i2, j1:j2]
275 subset_missing = {index for index in self.missing if grid_as_box.contains(y=index.i, x=index.j)}
276 return CellGridBounds(grid=self.grid, bbox=subset_bbox, missing=frozenset(subset_missing))
278 def serialize(self) -> CellGridBounds:
279 """Convert a bounds instance into a serializable object."""
280 return self
282 def deserialize(self) -> CellGridBounds:
283 """Deserialize a bounds object on the assumption it is a
284 `CellGridBounds`.
286 This method just returns the `CellGridBounds` itself, since that
287 already provides Pydantic serialization hooks. It exists for
288 compatibility with the `.Bounds` protocol.
289 """
290 return self
293class PatchDefinition(pydantic.BaseModel, frozen=True):
294 """Identifiers and geometry for a full patch."""
296 id: int = pydantic.Field(description="ID for the patch.")
297 index: YX[int] = pydantic.Field(description="2-d index of this patch within the tract.")
298 inner_bbox: Box = pydantic.Field(description="Inner bounding box of this patch.")
299 cells: CellGrid = pydantic.Field(description="Cell grid for the full patch.")
301 @property
302 def outer_bbox(self) -> Box:
303 """The outer bounding box of this patch (`.Box`)."""
304 return self.cells.bbox