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great_ai/utilities/unique.py

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+from typing import Any, Callable, Iterable, List, TypeVar
+
+T = TypeVar("T")
+
+
+def unique(values: Iterable[T], *, key: Callable[[T], Any] = lambda v: v) -> List[T]:
+    """Keep only the first occurrences while maintaining original order.
+
+    The equality check used for deduplication can be overridden using the `key` argument.
+
+    Examples:
+        >>> unique([1, 1, 5, 3, 3])
+        [1, 5, 3]
+        >>> unique([{'a': 1, 'b': 2}, {'a': 1, 'b': 3}], key=lambda v: v['a'])
+        [{'a': 1, 'b': 2}]
+        >>> unique([{'a': 1, 'b': 2}, {'a': 1, 'b': 3}], key=lambda v: v['b'])
+        [{'a': 1, 'b': 2}, {'a': 1, 'b': 3}]
+
+    Args:
+        values: An iterable containing your values
+        key: Override the identity function of the equality check.
+
+    Returns:
+        A deduplicated list.
+    """
+
+    key_values = {}
+    for v in values:
+        k = key(v)
+        if k not in key_values:
+            # dicts maintain insertion order: https://mail.python.org/pipermail/python-dev/2017-December/151283.html
+            key_values[k] = v
+
+    return list(key_values.values())