Add shortcut to merge parameter into base setup (#2540)

docs/en_US/autotune_ref.md

@@ -78,3 +78,9 @@
 ..  autoclass:: nni.bohb_advisor.bohb_advisor.BOHB
     :members:
 ```
+
+## Utilities
+
+```eval_rst
+..  autofunction:: nni.utils.merge_parameter
+```

examples/trials/mnist-pytorch/mnist.py

@@ -13,6 +13,7 @@ import torch
 import torch.nn as nn
 import torch.nn.functional as F
 import torch.optim as optim
+from nni.utils import merge_parameter
 from torchvision import datasets, transforms
 
 logger = logging.getLogger('mnist_AutoML')
@@ -157,8 +158,7 @@ if __name__ == '__main__':
         # get parameters form tuner
         tuner_params = nni.get_next_parameter()
         logger.debug(tuner_params)
-        params = vars(get_params())
-        params.update(tuner_params)
+        params = vars(merge_parameter(get_params(), tuner_params))
         print(params)
         main(params)
     except Exception as exception:

src/sdk/pynni/nni/utils.py

@@ -216,3 +216,43 @@ def json2parameter(x, is_rand, random_state, oldy=None, Rand=False, name=NodeTyp
     else:
         y = copy.deepcopy(x)
     return y
+
+
+def merge_parameter(base_params, override_params):
+    """
+    Update the parameters in ``base_params`` with ``override_params``.
+    Can be useful to override parsed command line arguments.
+
+    Parameters
+    ----------
+    base_params : namespace or dict
+        Base parameters. A key-value mapping.
+    override_params : dict or None
+        Parameters to override. Usually the parameters got from ``get_next_parameters()``.
+        When it is none, nothing will happen.
+
+    Returns
+    -------
+    namespace or dict
+        The updated ``base_params``. Note that ``base_params`` will be updated inplace. The return value is
+        only for convenience.
+    """
+    if override_params is None:
+        return base_params
+    is_dict = isinstance(base_params, dict)
+    for k, v in override_params.items():
+        if is_dict:
+            if k not in base_params:
+                raise ValueError('Key \'%s\' not found in base parameters.' % k)
+            if type(base_params[k]) != type(v) and base_params[k] is not None:
+                raise TypeError('Expected \'%s\' in override parameters to have type \'%s\', but found \'%s\'.' %
+                                (k, type(base_params[k]), type(v)))
+            base_params[k] = v
+        else:
+            if not hasattr(base_params, k):
+                raise ValueError('Key \'%s\' not found in base parameters.' % k)
+            if type(getattr(base_params, k)) != type(v) and getattr(base_params, k) is not None:
+                raise TypeError('Expected \'%s\' in override parameters to have type \'%s\', but found \'%s\'.' %
+                                (k, type(getattr(base_params, k)), type(v)))
+            setattr(base_params, k, v)
+    return base_params