Add map argument to audb.load_table()

audb/core/load.py

@@ -1635,6 +1635,7 @@ def load_table(
     table: str,
     *,
     version: str = None,
+    map: typing.Dict[str, typing.Union[str, typing.Sequence[str]]] = None,
     pickle_tables: bool = True,
     cache_root: str = None,
     num_workers: typing.Optional[int] = 1,
@@ -1654,6 +1655,15 @@ def load_table(
         name: name of database
         table: load table from database
         version: version of database
+        map: map scheme or scheme fields to column values.
+            For example if your table holds a column ``speaker`` with
+            speaker IDs, which is assigned to a scheme that contains a
+            dict mapping speaker IDs to age and gender entries,
+            ``map={'speaker': ['age', 'gender']}``
+            will replace the column with two new columns that map ID
+            values to age and gender, respectively.
+            To also keep the original column with speaker IDS, you can do
+            ``map={'speaker': ['speaker', 'age', 'gender']}``
         pickle_tables: if ``True``,
             tables are cached locally
             in their original format
@@ -1688,6 +1698,20 @@ def load_table(
         wav/03a01Nc.wav    neutral                1.00
         wav/03a01Wa.wav      anger                0.95
 
+        >>> df = load_table(
+        ...     "emodb",
+        ...     "files",
+        ...     version="1.4.1",
+        ...     map={"speaker": "age"},
+        ...     verbose=False,
+        ... )
+        >>> df[:3]
+                                         duration transcription  age
+        file
+        wav/03a01Fa.wav    0 days 00:00:01.898250           a01   31
+        wav/03a01Nc.wav    0 days 00:00:01.611250           a01   31
+        wav/03a01Wa.wav 0 days 00:00:01.877812500           a01   31
+
     """
     if version is None:
         version = latest_version(name)
@@ -1747,4 +1771,9 @@ def load_table(
                 )
             db[_table].load(table_file)
 
-    return db[table]._df
+    if map is None:
+        df = db[table]._df
+    else:
+        df = db[table].get(map=map)
+
+    return df

tests/test_load.py

@@ -1,6 +1,8 @@
 import os
+import random
 import shutil
 
+import numpy as np
 import pandas as pd
 import pytest
 
@@ -44,6 +46,8 @@ def dbs(tmpdir_factory, persistent_repository, storage_format):
         dictionary containing root folder for each version
 
     """
+    random.seed(1)
+
     # Collect single database paths
     # and return them in the end
     paths = {}
@@ -728,6 +732,74 @@ def test_load_table(version, table):
     assert files == expected_files
 
 
+@pytest.mark.parametrize(
+    "version, table, map, expected",
+    [
+        (
+            "1.0.0",
+            "files",
+            None,
+            pd.concat(
+                [
+                    pd.Series(
+                        index=audformat.filewise_index(
+                            [f"audio/00{n + 1}.wav" for n in range(5)]
+                        ),
+                        name="speaker",
+                        data=["adam", "adam", "eve", "eve", None],
+                        dtype=pd.CategoricalDtype(["adam", "eve"]),
+                    ),
+                    pd.Series(
+                        index=audformat.filewise_index(
+                            [f"audio/00{n + 1}.wav" for n in range(5)]
+                        ),
+                        name="misc",
+                        data=[0, 1, 1, 2, np.nan],
+                        dtype=pd.CategoricalDtype([0, 1, 2]),
+                    ),
+                ],
+                axis=1,
+            ),
+        ),
+        (
+            "1.0.0",
+            "files",
+            {"misc": "emotion"},
+            pd.concat(
+                [
+                    pd.Series(
+                        index=audformat.filewise_index(
+                            [f"audio/00{n + 1}.wav" for n in range(5)]
+                        ),
+                        name="speaker",
+                        data=["adam", "adam", "eve", "eve", None],
+                        dtype=pd.CategoricalDtype(["adam", "eve"]),
+                    ),
+                    pd.Series(
+                        index=audformat.filewise_index(
+                            [f"audio/00{n + 1}.wav" for n in range(5)]
+                        ),
+                        name="emotion",
+                        data=["positive", "positive", "positive", "negative", None],
+                        dtype=pd.CategoricalDtype(["positive", "neutral", "negative"]),
+                    ),
+                ],
+                axis=1,
+            ),
+        ),
+    ],
+)
+def test_load_table_map(version, table, map, expected):
+    df = audb.load_table(
+        DB_NAME,
+        table,
+        version=version,
+        map=map,
+        verbose=False,
+    )
+    pd.testing.assert_frame_equal(df, expected)
+
+
 @pytest.mark.parametrize(
     "version",
     [