Implement broadcast arrays

CHANGES

@@ -4,6 +4,7 @@ Pint Changelog
 0.24 (unreleased)
 -----------------
 
+- Implement numpy broadcast_array (Related to issue #981)
 - NumPy 2.0 support
   (PR #1985, #1971)
 - Implement numpy roll (Related to issue #981)

pint/facets/numpy/numpy_func.py

@@ -741,6 +741,23 @@ def _prod(a, *args, **kwargs):
     implement_prod_func(name)
 
 
+@implements("broadcast_arrays", "function")
+def _broadcast_arrays(*args, **kwargs):
+    # Simply need to map input units to onto list of outputs
+    input_units = []
+    unitless_args = []
+    for x in args:
+        if hasattr(x, "units"):
+            input_units.append(x.units)
+            unitless_args.append(x.m)
+        else:
+            input_units.append(1)
+            unitless_args.append(x)
+
+    res = np.broadcast_arrays(*unitless_args, **kwargs)
+    return [out * unit for out, unit in zip(res, input_units)]
+
+
 # Handle mutliplicative functions separately to deal with non-multiplicative units
 def _base_unit_if_needed(a):
     if a._is_multiplicative:
@@ -798,7 +815,6 @@ def implementation(a, b, **kwargs):
 for func_str in ("cross", "dot"):
     implement_mul_func(func_str)
 
-
 # Implement simple matching-unit or stripped-unit functions based on signature
 
 
@@ -991,7 +1007,6 @@ def implementation(a, *args, **kwargs):
     "vstack",
     "dstack",
     "column_stack",
-    "broadcast_arrays",
 ):
     implement_func(
         "function", func_str, input_units="all_consistent", output_unit="match_input"

pint/testsuite/test_numpy.py

@@ -288,6 +288,11 @@ def test_broadcast_arrays(self):
         result = np.broadcast_arrays(x, y, subok=True)
         helpers.assert_quantity_equal(result, expected)
 
+        helpers.assert_quantity_equal(
+            np.broadcast_arrays(self.q[:, 1], np.array([1, 2])),
+            [np.array([[2, 4], [2, 4]]) * self.ureg.m, np.array([1, 2])],
+        )
+
     def test_roll(self):
         helpers.assert_quantity_equal(
             np.roll(self.q, 1), [[4, 1], [2, 3]] * self.ureg.m