Add BoundarySides class

pyresample/boundary/__init__.py

@@ -17,6 +17,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 """The Boundary classes."""
 
+from pyresample.boundary.boundary_sides import BoundarySides  # noqa
 from pyresample.boundary.legacy_boundary import (  # noqa
     AreaBoundary,
     AreaDefBoundary,

pyresample/boundary/boundary_sides.py

@@ -0,0 +1,86 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+#
+# Copyright (c) 2014-2023 Pyresample developers
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""Define the BoundarySides class."""
+
+import logging
+
+import numpy as np
+
+logger = logging.getLogger(__name__)
+
+
+class BoundarySides:
+    """A class to represent the sides of an area boundary.
+
+    The sides are stored as a tuple of 4 numpy arrays, each representing the
+    coordinate (geographic or projected) of the vertices of the boundary side.
+    The sides must be stored in the order (top, right, left, bottom),
+    which refers to the side position with respect to the coordinate array.
+    The first row of the coordinate array correspond to the top side, the last row to the bottom side,
+    the first column to the left side and the last column to the right side.
+    Please note that the last vertex of each side must be equal to the first vertex of the next side.
+    """
+    __slots__ = ['_sides']
+
+    def __init__(self, sides: tuple[ArrayLike, ArrayLike, ArrayLike, ArrayLike]):
+        """Initialize the BoundarySides object."""
+        if len(sides) != 4 or not all(isinstance(side, np.ndarray) and side.ndim == 1 for side in sides):
+            raise ValueError("Sides must be a list of four numpy arrays.")
+
+        if not all(np.array_equal(sides[i][-1], sides[(i + 1) % 4][0]) for i in range(4)):
+            raise ValueError("The last element of each side must be equal to the first element of the next side.")
+
+        self._sides = tuple(sides)  # Store as a tuple
+
+    @property
+    def top(self):
+        """Return the vertices of the top side."""
+        return self._sides[0]
+
+    @property
+    def right(self):
+        """Return the vertices of the right side."""
+        return self._sides[1]
+
+    @property
+    def bottom(self):
+        """Return the vertices of the bottom side."""
+        return self._sides[2]
+
+    @property
+    def left(self):
+        """Return the vertices of the left side."""
+        return self._sides[3]
+
+    @property
+    def vertices(self):
+        """Return the vertices of the concatenated sides.
+
+        Note that the last element of each side is discarded to avoid duplicates.
+        """
+        return np.concatenate([side[:-1] for side in self._sides])
+
+    def __iter__(self):
+        """Return an iterator over the sides."""
+        return iter(self._sides)
+
+    def __getitem__(self, index):
+        """Return the side at the given index."""
+        if not isinstance(index, int) or not 0 <= index < 4:
+            raise IndexError("Index must be an integer from 0 to 3.")
+        return self._sides[index]

pyresample/test/test_boundary/test_boundary_sides.py

@@ -0,0 +1,107 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# pyresample, Resampling of remote sensing image data in python
+#
+# Copyright (C) 2010-2022 Pyresample developers
+#
+# This program is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation, either version 3 of the License, or (at your option) any
+# later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""Test the BoundarySides objects."""
+
+import numpy as np
+import pytest
+
+from pyresample.boundary import BoundarySides
+
+
+class TestBoundarySides:
+    """Test suite for the BoundarySides class with 1D numpy arrays for sides."""
+
+    def test_initialization_valid_input(self):
+        """Test initialization with valid 1D numpy array inputs."""
+        sides = [np.array([1, 2, 3]),  # top
+                 np.array([3, 4, 5]),  # right
+                 np.array([5, 6, 7]),  # bottom
+                 np.array([7, 8, 1])]  # left
+        boundary = BoundarySides(sides)
+        assert all(np.array_equal(boundary[i], sides[i]) for i in range(4))
+
+    def test_initialization_invalid_input(self):
+        """Test initialization with invalid inputs, such as wrong number of sides or non-1D arrays."""
+        with pytest.raises(ValueError):
+            BoundarySides([np.array([1, 2]),  # Invalid number of sides
+                           np.array([2, 3])])
+
+        with pytest.raises(ValueError):
+            BoundarySides([np.array([1, 2]),  # Non-1D arrays
+                           np.array([[2, 3], [4, 5]]),
+                           np.array([5, 6]),
+                           np.array([6, 7])])
+
+        with pytest.raises(ValueError):
+            BoundarySides([np.array([1, 2]),  # Invalid side connection
+                           np.array([3, 4]),
+                           np.array([4, 6]),
+                           np.array([6, 1])])
+
+    def test_property_accessors(self):
+        """Test property accessors with 1D numpy arrays."""
+        sides = [np.array([1, 2, 3]),  # top
+                 np.array([3, 4, 5]),  # right
+                 np.array([5, 6, 7]),  # bottom
+                 np.array([7, 8, 1])]  # left
+        boundary = BoundarySides(sides)
+        assert np.array_equal(boundary.top, sides[0])
+        assert np.array_equal(boundary.right, sides[1])
+        assert np.array_equal(boundary.bottom, sides[2])
+        assert np.array_equal(boundary.left, sides[3])
+
+    def test_vertices_property(self):
+        """Test the vertices property with concatenated 1D numpy arrays."""
+        sides = [np.array([1, 2, 3]),  # top
+                 np.array([3, 4, 5]),  # right
+                 np.array([5, 6, 7]),  # bottom
+                 np.array([7, 8, 1])]  # left
+        boundary = BoundarySides(sides)
+        expected_vertices = np.array([1, 2, 3, 4, 5, 6, 7, 8])
+        assert np.array_equal(boundary.vertices, expected_vertices)
+
+    def test_iteration(self):
+        """Test iteration over the 1D numpy array sides."""
+        sides = [np.array([1, 2, 3]),  # top
+                 np.array([3, 4, 5]),  # right
+                 np.array([5, 6, 7]),  # bottom
+                 np.array([7, 8, 1])]  # left
+        boundary = BoundarySides(sides)
+        for i, side in enumerate(boundary):
+            assert np.array_equal(side, sides[i])
+
+    def test_indexing_valid(self):
+        """Test valid indexing with 1D numpy arrays."""
+        sides = [np.array([1, 2, 3]),  # top
+                 np.array([3, 4, 5]),  # right
+                 np.array([5, 6, 7]),  # bottom
+                 np.array([7, 8, 1])]  # left
+        boundary = BoundarySides(sides)
+        for i in range(4):
+            assert np.array_equal(boundary[i], sides[i])
+
+    def test_indexing_invalid(self):
+        """Test indexing with invalid indices."""
+        sides = [np.array([1, 2, 3]),  # top
+                 np.array([3, 4, 5]),  # right
+                 np.array([5, 6, 7]),  # bottom
+                 np.array([7, 8, 1])]  # left
+        boundary = BoundarySides(sides)
+        with pytest.raises(IndexError):
+            boundary[4]  # Invalid index