⚡️ Speed up function _check_core_dims by 13%

xarray/core/computation.py

@@ -423,14 +423,20 @@ def _check_core_dims(signature, variable_args, name):
         # Check whether all the dims are on the variable. Note that we need the
         # `hasattr` to check for a dims property, to protect against the case where
         # a numpy array is passed in.
-        if hasattr(variable_arg, "dims") and set(core_dims) - set(variable_arg.dims):
-            missing += [[i, variable_arg, core_dims]]
+        if hasattr(variable_arg, "dims"):
+            missing_dims = set(core_dims) - set(variable_arg.dims)
+            if missing_dims:
+                missing.append((i, variable_arg, core_dims, missing_dims))
     if missing:
-        message = ""
-        for i, variable_arg, core_dims in missing:
-            message += f"Missing core dims {set(core_dims) - set(variable_arg.dims)} from arg number {i + 1} on a variable named `{name}`:\n{variable_arg}\n\n"
-        message += "Either add the core dimension, or if passing a dataset alternatively pass `on_missing_core_dim` as `copy` or `drop`. "
-        return message
+        lines = []
+        for i, variable_arg, core_dims, missing_dims in missing:
+            lines.append(
+                f"Missing core dims {missing_dims} from arg number {i + 1} on a variable named `{name}`:\n{variable_arg}\n"
+            )
+        lines.append(
+            "Either add the core dimension, or if passing a dataset alternatively pass `on_missing_core_dim` as `copy` or `drop`. "
+        )
+        return "\n".join(lines)
     return True