498 Add list to dict utility to parse variables (#904)

* [DLMED] add list_to_dict utility

* [MONAI] python code formatting

* [DLMED] update according to comments

* [MONAI] python code formatting

* [DLMED] add more tests

Co-authored-by: monai-bot <[email protected]>

Author: Nic-Ma

monai/utils/misc.py

@@ -12,6 +12,8 @@
 import collections.abc
 import itertools
 import random
+from ast import literal_eval
+from distutils.util import strtobool
 from typing import Any, Callable, Optional, Sequence, Tuple, Union
 
 import numpy as np
@@ -217,3 +219,37 @@ def set_determinism(
         torch.backends.cudnn.benchmark = False
     else:
         torch.backends.cudnn.deterministic = False
+
+
+def list_to_dict(items):
+    """
+    To convert a list of "key=value" pairs into a dictionary.
+    For examples: items: `["a=1", "b=2", "c=3"]`, return: {"a": "1", "b": "2", "c": "3"}.
+    If no "=" in the pair, use None as the value, for example: ["a"], return: {"a": None}.
+    Note that it will remove the blanks around keys and values.
+
+    """
+
+    def _parse_var(s):
+        items = s.split("=", maxsplit=1)
+        key = items[0].strip(" \n\r\t'")
+        value = None
+        if len(items) > 1:
+            value = items[1].strip(" \n\r\t'")
+        return key, value
+
+    d = dict()
+    if items:
+        for item in items:
+            key, value = _parse_var(item)
+
+            try:
+                if key in d:
+                    raise KeyError(f"encounter duplicated key {key}.")
+                d[key] = literal_eval(value)
+            except ValueError:
+                try:
+                    d[key] = bool(strtobool(str(value)))
+                except ValueError:
+                    d[key] = value
+    return d

tests/test_list_to_dict.py

@@ -0,0 +1,52 @@
+# Copyright 2020 MONAI Consortium
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#     http://www.apache.org/licenses/LICENSE-2.0
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+
+from parameterized import parameterized
+
+from monai.utils import list_to_dict
+
+TEST_CASE_1 = [
+    ["a=1", "b=2", "c=3", "d=4"],
+    {"a": 1, "b": 2, "c": 3, "d": 4},
+]
+
+TEST_CASE_2 = [
+    ["a=a", "b=b", "c=c", "d=d"],
+    {"a": "a", "b": "b", "c": "c", "d": "d"},
+]
+
+TEST_CASE_3 = [
+    ["a=0.1", "b=0.2", "c=0.3", "d=0.4"],
+    {"a": 0.1, "b": 0.2, "c": 0.3, "d": 0.4},
+]
+
+TEST_CASE_4 = [
+    ["a=True", "b=TRUE", "c=false", "d=FALSE"],
+    {"a": True, "b": True, "c": False, "d": False},
+]
+
+TEST_CASE_5 = [
+    ["a='1'", "b=2 ", " c = 3", "d='test'", "'e'=0", "f", "g=None"],
+    {"a": 1, "b": 2, "c": 3, "d": "test", "e": 0, "f": None, "g": None},
+]
+
+
+class TestListToDict(unittest.TestCase):
+    @parameterized.expand([TEST_CASE_1, TEST_CASE_2, TEST_CASE_3, TEST_CASE_4, TEST_CASE_5])
+    def test_value_shape(self, input, output):
+        result = list_to_dict(input)
+        self.assertDictEqual(result, output)
+
+
+if __name__ == "__main__":
+    unittest.main()