use description as band name (#802)

Author: vincentsarago

CHANGES.md

@@ -1,6 +1,57 @@
 
 # Unreleased
 
+# 8.0.0
+
+* use **description** as band name (instead of `b{ix}`) in `Reader`'s outputs **breaking change**
+
+```python
+# before
+with Reader("tests/fixtures/cog_tags.tif") as src:
+    info = src.info()
+    img = src.preview()
+    stats = src.statistics()
+
+    print(info.band_descriptions)
+    >> [('b1', 'Green')]
+
+    print(img.band_names)
+    >> ['b1']
+
+    print(list(stats))
+    >> ['b1']
+
+# now
+with Reader("tests/fixtures/cog_tags.tif") as src:
+    info = src.info()
+    img = src.preview()
+    stats = src.statistics()
+
+    print(info.band_descriptions)
+    >> [('b1', 'Green')]
+
+    print(img.band_names)
+    >> ['Green']
+
+    print(list(stats))
+    >> ['Green']
+
+    # Band without description
+    with Reader("tests/fixtures/cog.tif") as src:
+        info = src.info()
+        stats = src.statistics()
+        img = src.preview()
+
+    print(info.band_descriptions)
+    >> [('b1', '')]
+
+    print(list(stats))
+    >> ['b1']
+
+    print(list(stats))
+    >> ['b1']
+```
+
 * only cast data to `uint8` if colormap values are of type `uint8`
 * add `alpha_mask` attribute to `ImageData` class
 * allow partial alpha values from alpha band

rio_tiler/reader.py

@@ -314,7 +314,7 @@ def read(
             data,
             bounds=out_bounds,
             crs=dataset.crs,
-            band_names=[f"b{idx}" for idx in indexes],
+            band_names=[dataset.descriptions[ix - 1] or f"b{idx}" for idx in indexes],
             dataset_statistics=dataset_statistics,
             metadata=dataset.tags(),
         )

tests/test_io_rasterio.py

@@ -414,6 +414,13 @@ def test_statistics():
         assert stats["b1*2"]
         assert stats["b1"].min == stats["b1*2"].min / 2
 
+    with Reader(COG_TAGS) as src:
+        stats = src.statistics()
+        assert len(stats) == 1
+        assert isinstance(stats["Green"], BandStatistics)
+        assert stats["Green"].percentile_2
+        assert stats["Green"].percentile_98
+
 
 def test_Reader_Options():
     """Set options in reader."""
@@ -1010,10 +1017,10 @@ def test_metadata_img():
         img = src.preview()
         assert img.dataset_statistics
         assert img.metadata
-        assert img.band_names == ["b1"]
+        assert img.band_names == ["Green"]
 
         stats = src.statistics()
-        assert "b1" in stats
+        assert "Green" in stats
 
 
 def test_feature_statistics():