If you update the value of an existing key, then the order remains unchanged.Its a dictionary subclass specially designed to remember the order of items, which is defined by the insertion order of keys.
![]() Python Sort Dictionary Update The ValuePython developers were used to this fact, and they relied on lists or other sequences when they needed to keep their data in order. With time, developers found a need for a new type of dictionary, one that would keep its items ordered. Its main goal was to remember the order of items as defined by the order in which keys were inserted. That, in turn, allowed for a more straightforward implementation of specific algorithms that rely on this property. However, OrderedDict iterates over keys and values in the same order that the keys were inserted. If a new entry overwrites an existing entry, then the order of items is left unchanged. If an entry is deleted and reinserted, then it will be moved to the end of the dictionary. This new implementation represents a big win in terms of memory usage and iteration efficiency. Additionally, the new implementation provides a new and somewhat unexpected feature: dict objects now keep their items in the same order they were introduced. Initially, this feature was considered an implementation detail, and the documentation advised against relying on it. The primary goals of that design were compactness and faster iteration over the dense arrays of keys and values. The design can maintain order but that is not its specialty. The primary goal was to have efficient maintenance of order even for severe workloads such as that imposed by the lrucache which frequently alters order without touching the underlying dict. Intentionally, the OrderedDict has a design that prioritizes ordering capabilities at the expense of additional memory overhead and a constant factor worse insertion time. ![]() The OrderedDict needs to be good at those operations because that is what differentiates it from regular dicts. Source ). So, from that point on, developers could rely on dict when they needed a dictionary that keeps its items ordered. Python Sort Dictionary Code Needs OrYoure clearly communicating that your code needs or relies on the order of items in the underlying dictionary. Relying on regular dict objects to preserve the order of items will break your code in environments that run versions of Python older than 3.6. Nowadays, OrderedDict still offers interesting and valuable features that you might want to consider when selecting a tool for a given job. When you iterate over an OrderedDict object, items are traversed in the original order.
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