library: Add imagery Python library module to grass.script

python/grass/script/Makefile

@@ -5,7 +5,7 @@ include $(MODULE_TOPDIR)/include/Make/Python.make
 
 DSTDIR = $(ETC)/python/grass/script
 
-MODULES = core db raster raster3d vector array setup task utils
+MODULES = core db imagery raster raster3d vector array setup task utils
 
 PYFILES := $(patsubst %,$(DSTDIR)/%.py,$(MODULES) __init__)
 PYCFILES := $(patsubst %,$(DSTDIR)/%.pyc,$(MODULES) __init__)

python/grass/script/imagery.py

@@ -0,0 +1,150 @@
+"""
+Imagery related functions to be used in Python scripts.
+
+Usage:
+
+::
+
+    import grass.script as gs
+
+    gs.imagery.group_to_dict(imagery_group)
+    ...
+
+(C) 2024 by Stefan Blumentrath and the GRASS Development Team
+This program is free software under the GNU General Public
+License (>=v2). Read the file COPYING that comes with GRASS
+for details.
+
+.. sectionauthor:: Stefan Blumentrath
+"""
+
+from .core import read_command, warning, fatal
+from .raster import raster_info
+
+
+def group_to_dict(
+    imagery_group_name,
+    subgroup=None,
+    dict_keys="semantic_labels",
+    dict_values="map_names",
+    fill_semantic_label=True,
+    env=None,
+):
+    """Create a dictionary to represent an imagery group with metadata.
+
+    Depending on the dict_keys option, the returned dictionary uses either
+    the names of the raster maps ("map_names"), their row indices in the group
+    ("indices") or their associated semantic_labels ("semantic_labels") as keys.
+    The default is to use semantic_labels. Note that map metadata
+    of the maps in the group have to be read to get the semantic label,
+    in addition to the group file. The same metadata is read when the
+    "metadata" is requested as dict_values. Other supported dict_values
+    are "map_names" (default), "semantic_labels", or "indices".
+
+    The function can also operate on the level of subgroups. In case a
+    non-existing (or empty sub-group) is requested a warning is printed
+    and an empty dictionary is returned (following the behavior of i.group).
+
+    Example::
+
+    >>> run_command("g.copy", raster="lsat7_2000_10,lsat7_2000_10")
+    >>> run_command("r.support", raster="lsat7_2000_10", semantic_label="L8_1")
+    >>> run_command("g.copy", raster="lsat7_2000_20,lsat7_2000_20")
+    >>> run_command("r.support", raster="lsat7_2000_20", semantic_label="L8_2")
+    >>> run_command("g.copy", raster="lsat7_2000_30,lsat7_2000_30")
+    >>> run_command("r.support", raster="lsat7_2000_30", semantic_label="L8_3")
+    >>> run_command("i.group", group="L8_group",
+    >>>             input="lsat7_2000_10,lsat7_2000_20,lsat7_2000_30")
+    >>> group_to_dict("L8_group")  # doctest: +ELLIPSIS
+    {"L8_1": "lsat7_2000_10", ... "L8_3": "lsat7_2000_30"}
+    >>> run_command("g.remove", flags="f", type="group", name="L8_group")
+    >>> run_command("g.remove", flags="f", type="raster",
+    >>>             name="lsat7_2000_10,lsat7_2000_20,lsat7_2000_30")
+
+    :param str imagery_group_name: Name of the imagery group to process (or None)
+    :param str subgroup: Name of the imagery sub-group to process (or None)
+    :param str dict_keys: What to use as key for dictionary. It can be either
+                         "semantic_labels" (default), "map_names" or "indices"
+    :param str dict_values: What to use as values for dictionary. It can be either
+                           "map_names" (default), "semanic_labels", "indices" or
+                           "metadata" (to return dictionaries with full map metadata)
+    :param bool fill_semantic_label: If maps in a group do not have a semantic
+                                     label, their index in the group is used
+                                     instead (default). Otherwise None / "none"
+                                     is used.
+    :param dict env: Environment to use when parsing the imagery group
+
+    :return: dictionary representing an imagery group with it's maps and their
+             semantic labels, row indices in the group, or metadata
+    :rtype: dict
+    """
+    group_dict = {}
+    maps_in_group = (
+        read_command(
+            "i.group",
+            group=imagery_group_name,
+            subgroup=subgroup,
+            flags="g",
+            quiet=True,
+            env=env,
+        )
+        .strip()
+        .split()
+    )
+
+    if dict_keys not in {"indices", "map_names", "semantic_labels"}:
+        raise ValueError(f"Invalid dictionary keys <{dict_keys}> requested")
+
+    if dict_values not in {"indices", "map_names", "semantic_labels", "metadata"}:
+        raise ValueError(f"Invalid dictionary values <{dict_values}> requested")
+
+    if subgroup and not maps_in_group:
+        warning(
+            _("Empty result returned for subgroup <{sg}> in group <{g}>").format(
+                sg=subgroup, g=imagery_group_name
+            )
+        )
+
+    for idx, raster_map in enumerate(maps_in_group):
+        raster_map_info = None
+        # Get raster metadata if needed
+        if (
+            dict_values in {"semantic_labels", "metadata"}
+            or dict_keys == "semantic_labels"
+        ):
+            raster_map_info = raster_info(raster_map, env=env)
+
+        # Get key for dictionary
+        if dict_keys == "indices":
+            key = str(idx + 1)
+        elif dict_keys == "map_names":
+            key = raster_map
+        elif dict_keys == "semantic_labels":
+            key = raster_map_info["semantic_label"]
+            if not key or key == '"none"':
+                if fill_semantic_label:
+                    key = str(idx + 1)
+                else:
+                    fatal(
+                        _(
+                            "Semantic label missing for raster map {m} in group <{g}>."
+                        ).format(m=raster_map, g=imagery_group_name)
+                    )
+
+        if dict_values == "indices":
+            val = str(idx + 1)
+        elif dict_values == "map_names":
+            val = raster_map
+        elif dict_values == "semantic_labels":
+            val = raster_map_info["semantic_label"]
+        elif dict_values == "metadata":
+            val = raster_map_info
+        if key in group_dict:
+            warning(
+                _(
+                    "Key {k} from raster map {m} already present in group dictionary."
+                    "Overwriting existing entry..."
+                ).format(k=key, r=raster_map)
+            )
+        group_dict[key] = val
+    return group_dict

python/grass/script/testsuite/test_imagery.py

@@ -0,0 +1,163 @@
+from grass.exceptions import CalledModuleError
+from grass.gunittest.case import TestCase
+from grass.gunittest.main import test
+
+import grass.script as gs
+
+
+class TestImageryGroupToDict(TestCase):
+    """Tests function `group_to_dict` that returns raster maps
+    from an imagery group and their metadata."""
+
+    @classmethod
+    def setUpClass(cls):
+        cls.bands = [1, 2, 3]
+        cls.raster_maps = [f"lsat7_2002_{band}0" for band in cls.bands]
+        cls.group = "L8_group"
+        cls.subgroup = "L8_group_subgroup"
+        # Create input maps with label and group
+        for band in cls.bands:
+            cls.runModule(
+                "g.copy", raster=[f"lsat7_2002_{band}0", f"lsat7_2002_{band}0"]
+            )
+            cls.runModule(
+                "r.support", map=f"lsat7_2002_{band}0", semantic_label=f"L8_{band}"
+            )
+        cls.runModule("i.group", group=cls.group, input=cls.raster_maps)
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.runModule("g.remove", type="raster", name=cls.raster_maps, flags="f")
+        cls.runModule("g.remove", type="group", name=cls.group, flags="f")
+
+    def test_basic_group_dict_defaults(self):
+        """Test with semantic labels as keys and map names as values (defaults)"""
+        ref_dict = {f"L8_{band}": f"lsat7_2002_{band}0" for band in self.bands}
+        group_info = gs.imagery.group_to_dict(self.group)
+        # Check that a dict is returned
+        self.assertIsInstance(group_info, dict)
+        self.assertListEqual(list(ref_dict.keys()), list(group_info.keys()))
+        self.assertListEqual(
+            list(ref_dict.values()), [val.split("@")[0] for val in group_info.values()]
+        )
+
+    def test_non_existing_group(self):
+        """Test that function fails if group does not exist"""
+        # Non existing group
+        self.assertRaises(
+            CalledModuleError, gs.imagery.group_to_dict, "non_existing_group"
+        )
+
+    def test_invalid_dict_key(self):
+        """Test that function fails if invalid keys are requested"""
+        self.assertRaises(
+            ValueError,
+            gs.imagery.group_to_dict,
+            self.group,
+            dict_keys="invalid_dict_key",
+        )
+
+    def test_invalid_dict_value(self):
+        """Test that function fails if invalid values are requested"""
+        self.assertRaises(
+            ValueError,
+            gs.imagery.group_to_dict,
+            self.group,
+            dict_values="invalid_dict_value",
+        )
+
+    def test_missing_subgroup(self):
+        """Test that empty dict is returned if subgroup does not exist"""
+        group_info = gs.imagery.group_to_dict(
+            self.group, subgroup="non_existing_subgroup"
+        )
+
+        # Check that an empty dict is returned
+        self.assertDictEqual(group_info, {})
+
+    def test_basic_group_map_keys(self):
+        """Test with map_names as keys and semantic_labels as values"""
+        ref_dict = {f"lsat7_2002_{band}0": f"L8_{band}" for band in self.bands}
+        group_info = gs.imagery.group_to_dict(
+            self.group, dict_keys="map_names", dict_values="semantic_labels"
+        )
+        # Check that a dict is returned
+        self.assertIsInstance(group_info, dict)
+        self.assertListEqual(
+            list(ref_dict.keys()), [key.split("@")[0] for key in group_info.keys()]
+        )
+        self.assertListEqual(list(ref_dict.values()), list(group_info.values()))
+
+    def test_basic_group_index_keys(self):
+        """Test with indices as keys and mapnames as values"""
+        ref_dict = {str(band): f"lsat7_2002_{band}0" for band in self.bands}
+        group_info = gs.imagery.group_to_dict(self.group, dict_keys="indices")
+        # Check that a dict is returned
+        self.assertIsInstance(group_info, dict)
+        self.assertListEqual(list(ref_dict.keys()), list(group_info.keys()))
+        self.assertListEqual(
+            list(ref_dict.values()),
+            [val.split("@")[0] for val in group_info.values()],
+        )
+
+    def test_full_info_group_label_keys(self):
+        """Test with semantic labels as keys and full map metadata as values"""
+        group_info = gs.imagery.group_to_dict(self.group, dict_values="metadata")
+        # Check that a dict is returned
+        self.assertIsInstance(group_info, dict)
+        self.assertListEqual(
+            [f"L8_{band}" for band in self.bands],
+            [key.split("@")[0] for key in group_info.keys()],
+        )
+        for band in self.bands:
+            # Take some metadata keys from raster_info
+            for metadata_key in [
+                "north",
+                "nsres",
+                "cols",
+                "datatype",
+                "map",
+                "date",
+                "semantic_label",
+                "comments",
+            ]:
+                self.assertIn(metadata_key, group_info[f"L8_{band}"])
+
+    def test_full_info_group_label_keys_subgroup(self):
+        """Test with map names as keys and full map metadata as values"""
+        metadata_keys = {
+            "north",
+            "nsres",
+            "cols",
+            "datatype",
+            "map",
+            "date",
+            "semantic_label",
+            "comments",
+        }
+        self.runModule(
+            "i.group", group=self.group, subgroup=self.subgroup, input=self.raster_maps
+        )
+        group_info = gs.imagery.group_to_dict(
+            self.group,
+            subgroup=self.subgroup,
+            dict_keys="map_names",
+            dict_values="metadata",
+        )
+        # Check that a dict is returned
+        self.assertIsInstance(group_info, dict)
+        self.assertListEqual(
+            [f"lsat7_2002_{band}0" for band in self.bands],
+            [key.split("@")[0] for key in group_info.keys()],
+        )
+        for key, val in group_info.items():
+            # Check keys
+            self.assertTrue(key.startswith("lsat7_2002_"))
+            # Check values
+            self.assertIsInstance(val, dict)
+            # Take some metadata keys from raster_info
+            self.assertTrue(metadata_keys.issubset(set(val.keys())))
+
+
+if __name__ == "__main__":
+    test()