Support calling numpy ufuncs assigned to top-level names in formulas (#…

…4759)

* Support alias-ed numpy ufunc in formulas

* Add meaningful comments to the changes

py/server/deephaven/table.py

@@ -387,7 +387,15 @@ def _encode_signature(fn: Callable) -> str:
 
     If a parameter or the return of the function is not annotated, the default 'O' - object type, will be used.
     """
-    sig = inspect.signature(fn)
+    try:
+        sig = inspect.signature(fn)
+    except:
+        # in case inspect.signature() fails, we'll just use the default 'O' - object type.
+        # numpy ufuncs actually have signature encoded in their 'types' attribute, we want to better support
+        # them in the future (https://github.com/deephaven/deephaven-core/issues/4762)
+        if type(fn) == np.ufunc:
+            return "O"*fn.nin + "->" + "O"
+        return "->O"
 
     np_type_codes = []
     for n, p in sig.parameters.items():
@@ -429,8 +437,8 @@ def _py_udf(fn: Callable):
     if hasattr(fn, "return_type"):
         return fn
     ret_dtype = _udf_return_dtype(fn)
-    return_array = False
 
+    return_array = False
     # If the function is a numba guvectorized function, examine the signature of the function to determine if it
     # returns an array.
     if isinstance(fn, numba.np.ufunc.gufunc.GUFunc):
@@ -439,12 +447,20 @@ def _py_udf(fn: Callable):
         if rtype:
             return_array = True
     else:
-        return_annotation = _parse_annotation(inspect.signature(fn).return_annotation)
-        component_type = _component_np_dtype_char(return_annotation)
-        if component_type:
-            ret_dtype = dtypes.from_np_dtype(np.dtype(component_type))
-            if ret_dtype in _BUILDABLE_ARRAY_DTYPE_MAP:
-                return_array = True
+        try:
+            return_annotation = _parse_annotation(inspect.signature(fn).return_annotation)
+        except ValueError:
+            # the function has no return annotation, and since we can't know what the exact type is, the return type
+            # defaults to the generic object type therefore it is not an array of a specific type,
+            # but see (https://github.com/deephaven/deephaven-core/issues/4762) for future imporvement to better support
+            # numpy ufuncs.
+            pass
+        else:
+            component_type = _component_np_dtype_char(return_annotation)
+            if component_type:
+                ret_dtype = dtypes.from_np_dtype(np.dtype(component_type))
+                if ret_dtype in _BUILDABLE_ARRAY_DTYPE_MAP:
+                    return_array = True
 
     @wraps(fn)
     def wrapper(*args, **kwargs):

py/server/tests/test_pyfunc_return_java_values.py

@@ -271,6 +271,27 @@ def f1(col) -> Optional[List[int]]:
         self.assertEqual(t.columns[0].data_type, dtypes.long_array)
         self.assertEqual(t.to_string().count("null"), 5)
 
+    def test_np_ufunc(self):
+        # no vectorization and no type inference
+        npsin = np.sin
+        t = empty_table(10).update(["X1 = npsin(i)"])
+        self.assertEqual(t.columns[0].data_type, dtypes.PyObject)
+        t2 = t.update("X2 = X1.getDoubleValue()")
+        self.assertEqual(t2.columns[1].data_type, dtypes.double)
+
+        import numba
+
+        # numba vectorize decorator doesn't support numpy ufunc
+        with self.assertRaises(TypeError):
+            nbsin = numba.vectorize([numba.float64(numba.float64)])(np.sin)
+
+        # this is the workaround that utilizes vectorization and type inference
+        @numba.vectorize([numba.float64(numba.float64)], nopython=True)
+        def nbsin(x):
+            return np.sin(x)
+        t3 = empty_table(10).update(["X3 = nbsin(i)"])
+        self.assertEqual(t3.columns[0].data_type, dtypes.double)
+
 
 if __name__ == '__main__':
     unittest.main()