Update index_data.py for datatype conversion and alignment (#1813)

* Update index_data.py for data convertion and alignment

* Update qlib/utils/index_data.py

* Update qlib/utils/index_data.py

* fix linting

---------

Co-authored-by: taozhiwang <taozhiwa@gmail.com>
Co-authored-by: you-n-g <you-n-g@users.noreply.github.com>

qlib/utils/index_data.py

@@ -108,6 +108,12 @@ def __init__(self, idx_list: Union[List, pd.Index, "Index", int]):
             self.index_map = self.idx_list = np.arange(idx_list)
             self._is_sorted = True
         else:
+            # Check if all elements in idx_list are of the same type
+            if not all(isinstance(x, type(idx_list[0])) for x in idx_list):
+                raise TypeError("All elements in idx_list must be of the same type")
+            # Check if all elements in idx_list are of the same datetime64 precision
+            if isinstance(idx_list[0], np.datetime64) and not all(x.dtype == idx_list[0].dtype for x in idx_list):
+                raise TypeError("All elements in idx_list must be of the same datetime64 precision")
             self.idx_list = np.array(idx_list)
             # NOTE: only the first appearance is indexed
             self.index_map = dict(zip(self.idx_list, range(len(self))))
@@ -131,7 +137,12 @@ def _convert_type(self, item):
         if self.idx_list.dtype.type is np.datetime64:
             if isinstance(item, pd.Timestamp):
                 # This happens often when creating index based on pandas.DatetimeIndex and query with pd.Timestamp
-                return item.to_numpy()
+                return item.to_numpy().astype(self.idx_list.dtype)
+            elif isinstance(item, np.datetime64):
+                # This happens often when creating index based on np.datetime64 and query with another precision
+                return item.astype(self.idx_list.dtype)
+            # NOTE: It is hard to consider every case at first.
+            # We just try to cover part of cases to make it more user-friendly
         return item
 
     def index(self, item) -> int:

tests/misc/test_index_data.py

@@ -94,6 +94,24 @@ def test_corner_cases(self):
         print(sd)
         self.assertTrue(sd.iloc[0] == 2)
 
+        # test different precisions of time data
+        timeindex = [
+            np.datetime64("2024-06-22T00:00:00.000000000"),
+            np.datetime64("2024-06-21T00:00:00.000000000"),
+            np.datetime64("2024-06-20T00:00:00.000000000"),
+        ]
+        sd = idd.SingleData([1, 2, 3], index=timeindex)
+        self.assertTrue(
+            sd.index.index(np.datetime64("2024-06-21T00:00:00.000000000"))
+            == sd.index.index(np.datetime64("2024-06-21T00:00:00"))
+        )
+        self.assertTrue(sd.index.index(pd.Timestamp("2024-06-21 00:00")) == 1)
+
+        # Bad case: the input is not aligned
+        timeindex[1] = (np.datetime64("2024-06-21T00:00:00.00"),)
+        with self.assertRaises(TypeError):
+            sd = idd.SingleData([1, 2, 3], index=timeindex)
+
     def test_ops(self):
         sd1 = idd.SingleData([1, 2, 3, 4], index=["foo", "bar", "f", "g"])
         sd2 = idd.SingleData([1, 2, 3, 4], index=["foo", "bar", "f", "g"])