enh: support passing a single file to concatenated_hdf5_data

CHANGELOG

@@ -1,3 +1,5 @@
+0.25.4
+ - enh: support passing a single file to `concatenated_hdf5_data`
 0.25.3
  - enh: request single threaded operations when going into mp.Process (#17)
  - enh: new module `dcnum.single_thread_osenv`

src/dcnum/read/hdf5_data.py

@@ -593,8 +593,11 @@ def concatenated_hdf5_data(paths: List[pathlib.Path],
         raise ValueError(
             f"Invalid type for `path_out`: {type(path_out)} ({path_out}")
 
-    if len(paths) <= 1:
-        raise ValueError("Please specify at least two files in `paths`!")
+    if len(paths) == 0:
+        raise ValueError("Please specify at least one file in `paths`!")
+    elif len(paths) == 1:
+        warnings.warn("Only one file passed to `concatenated_hdf5_data`; this "
+                      "is equivalent to using `HDF5Data`, but slower.")
 
     frames = []
 

tests/test_read_concat_hdf5.py

@@ -89,9 +89,15 @@ def test_concat_invalid_input_path():
 
 
 def test_concat_invalid_input_path_number():
+    with pytest.raises(ValueError, match="Please specify at least one"):
+        read.concatenated_hdf5_data([])
+
+
+def test_concat_invalid_input_path_number_warn():
     path = retrieve_data("fmt-hdf5_cytoshot_full-features_2023.zip")
-    with pytest.raises(ValueError, match="Please specify at least two"):
-        read.concatenated_hdf5_data([path])
+    with pytest.warns(UserWarning, match="is equivalent to using"):
+        hd = read.concatenated_hdf5_data([path])
+        assert len(hd) == 40
 
 
 def test_concat_specify_input_feature_number():