fix: normalize frequency strings so '1day' and 'day' are equivalent

qlib/utils/resam.py

@@ -9,6 +9,26 @@
 from ..config import C
 
 
+def normalize_freq(freq: str) -> str:
+    """Normalize a frequency string to its canonical form.
+
+    This ensures that equivalent frequency representations like
+    "1day" and "day", or "1min" and "min", are mapped to the
+    same canonical string.
+
+    Parameters
+    ----------
+    freq : str
+        Raw frequency string, e.g. "1day", "day", "5min", "1min", "min"
+
+    Returns
+    -------
+    str
+        Canonical frequency string, e.g. "day", "5min", "min"
+    """
+    return str(Freq(freq))
+
+
 def resam_calendar(
     calendar_raw: np.ndarray, freq_raw: Union[str, Freq], freq_sam: Union[str, Freq], region: str = None
 ) -> np.ndarray:
@@ -79,6 +99,7 @@ def get_higher_eq_freq_feature(instruments, fields, start_time=None, end_time=No
 
     from ..data.data import D  # pylint: disable=C0415
 
+    freq = normalize_freq(freq)
     try:
         _result = D.features(instruments, fields, start_time, end_time, freq=freq, disk_cache=disk_cache)
         _freq = freq

tests/test_freq_normalization.py

@@ -0,0 +1,55 @@
+"""Test for Issue #1925: Freq normalization — '1day' vs 'day' equivalence."""
+import pytest
+from qlib.utils.resam import normalize_freq
+from qlib.utils.time import Freq
+
+
+class TestFreqNormalization:
+    """Test that equivalent frequency strings normalize to the same canonical form."""
+
+    def test_day_equivalents(self):
+        assert normalize_freq("day") == normalize_freq("1day")
+        assert normalize_freq("day") == normalize_freq("1d")
+        assert normalize_freq("day") == normalize_freq("d")
+
+    def test_min_equivalents(self):
+        assert normalize_freq("min") == normalize_freq("1min")
+        assert normalize_freq("min") == normalize_freq("minute")
+        assert normalize_freq("min") == normalize_freq("1minute")
+
+    def test_multi_count_preserved(self):
+        assert normalize_freq("5min") == normalize_freq("5min")
+        assert normalize_freq("5min") == normalize_freq("5minute")
+        assert normalize_freq("30min") == "30min"
+
+    def test_week_equivalents(self):
+        assert normalize_freq("week") == normalize_freq("1week")
+        assert normalize_freq("week") == normalize_freq("1w")
+        assert normalize_freq("week") == normalize_freq("w")
+
+    def test_month_equivalents(self):
+        assert normalize_freq("month") == normalize_freq("1month")
+        assert normalize_freq("month") == normalize_freq("1mon")
+        assert normalize_freq("month") == normalize_freq("mon")
+
+    def test_normalize_idempotent(self):
+        """Normalizing an already-normalized string should return the same result."""
+        for freq in ["day", "min", "5min", "week", "month", "30min"]:
+            assert normalize_freq(freq) == normalize_freq(normalize_freq(freq))
+
+    def test_freq_object_equality(self):
+        """Freq objects from equivalent strings should be equal."""
+        assert Freq("1day") == Freq("day")
+        assert Freq("1min") == Freq("min")
+        assert Freq("1d") == Freq("day")
+        assert Freq("5min") == Freq("5minute")
+
+    def test_canonical_strings(self):
+        """Canonical output should use short forms."""
+        assert normalize_freq("1day") == "day"
+        assert normalize_freq("1min") == "1min"
+        assert normalize_freq("5minute") == "5min"
+
+
+if __name__ == "__main__":
+    pytest.main([__file__, "-v"])