\n
True<\/p>\n<\/div>\n
OrderedDict Syntax in Python<\/h3>\n
To define an OrderedDict in Python, we import it from the module \u2018collections\u2019. Let us see this Python ordereddict example.<\/p>\n
>>> from collections import OrderedDict<\/pre>\nThen, we call this factory function and assign it to a variable in Python.<\/p>\n
>>> d=OrderedDict()<\/pre>\nWe now add some key-value pairs to it.<\/p>\n
>>> d['a']=1\r\n>>> d['e']=5\r\n>>> d['d']=4\r\n>>> d['b']=2\r\n>>> d['c']=3<\/pre>\nNow, if we access \u2018d\u2019, we see that it preserved the order in which we defined the key-value pairs.<\/p>\n
>>> d<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘a’, 1), (‘e’, 5), (‘d’, 4), (‘b’, 2), (‘c’, 3)])<\/p>\n<\/div>\n
Comparing to a Regular Dictionary<\/h3>\n
Let\u2019s try this with a regular dictionary. If we declared this as a regular dictionary, it would produce the pairs according to how the keys are stored in a hash table.<\/p>\n
This depends on a random value to reduce collisions.<\/p>\n
1. Equality<\/h4>\n
To a regular dictionary, the order does not matter. Let u take another Python ordereddict example.<\/p>\n
>>> {'a': 1, 'e': 5, 'd': 4, 'b': 2, 'c': 3}=={'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5}<\/pre>\nOutput<\/strong><\/p>\n\n
True<\/p>\n<\/div>\n
To Python, these two are equal. Let\u2019s create another OrderedDict, and check if it is the same as the OrderedDict \u2018d\u2019 we defined above.<\/p>\n
>>> e=OrderedDict()\r\n>>> e['a']=1\r\n>>> e['b']=2\r\n>>> e['c']=3\r\n>>> e['d']=4\r\n>>> e['e']=5\r\n>>> e<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘a’, 1), (‘b’, 2), (‘c’, 3), (‘d’, 4), (‘e’, 5)])<\/p>\n<\/div>\n
Now, let\u2019s check if they\u2019re equal.<\/p>\n
>>> d==e<\/pre>\nOutput<\/strong><\/p>\n\n
False<\/p>\n<\/div>\n
As you can see, they\u2019re not.<\/p>\n
How to Reorder Python OrderedDict?<\/h3>\n
To reorder a key-value pair to the front or the end of an OrderedDict in Python, we have the move_to_end() method. Look, this is \u2018d\u2019:<\/p>\n
>>> d<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘a’, 1), (‘e’, 5), (‘d’, 4), (‘b’, 2), (‘c’, 3)])<\/p>\n<\/div>\n
Now, let\u2019s move (\u2018e\u2019,5) to the end.<\/p>\n
>>> d.move_to_end('e')\r\n>>> d<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘a’, 1), (‘d’, 4), (‘b’, 2), (‘c’, 3), (‘e’, 5)])<\/p>\n<\/div>\n
This method takes a key as an argument. But it may also take another argument- \u2018last\u2019. This may take one of two values: True or False.<\/p>\n
When true, the item is moved to the end. And when false, it is moved to the front.<\/p>\n
>>> d.move_to_end('a',last=True)\r\n>>> d<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘d’, 4), (‘b’, 2), (‘c’, 3), (‘e’, 5), (‘a’, 1)])<\/p>\n<\/div>\n
Here, we moved (\u2018a\u2019,1) to the end. Now, let\u2019s move it back to the front.<\/p>\n
>>> d.move_to_end('a',last=False)\r\n>>> d<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘a’, 1), (‘d’, 4), (‘b’, 2), (‘c’, 3), (‘e’, 5)])<\/p>\n<\/div>\n
Now, to sort this, we do the following:<\/p>\n
>>> d.move_to_end('b')\r\n>>> d<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘a’, 1), (‘d’, 4), (‘c’, 3), (‘e’, 5), (‘b’, 2)])<\/p>\n<\/div>\n
>>> d.move_to_end('c')\r\n>>> d<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘a’, 1), (‘d’, 4), (‘e’, 5), (‘b’, 2), (‘c’, 3)])<\/p>\n<\/div>\n
>>> d.move_to_end('d')\r\n>>> d<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘a’, 1), (‘e’, 5), (‘b’, 2), (‘c’, 3), (‘d’, 4)])<\/p>\n<\/div>\n
>>> d.move_to_end('e')\r\n>>> d<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘a’, 1), (‘b’, 2), (‘c’, 3), (‘d’, 4), (‘e’, 5)])<\/p>\n<\/div>\n
Assigning a Key Again in Python OrderedDict<\/h3>\n
Let\u2019s define a new OrderedDict in Python for this example.<\/p>\n
>>> f=OrderedDict()\r\n>>> f['c']=3\r\n>>> f['e']=5\r\n>>> f['a']=1\r\n>>> f['b']=2\r\n>>> f['d']=4\r\n>>> f<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘c’, 3), (‘e’, 5), (‘a’, 1), (‘b’, 2), (‘d’, 4)])<\/p>\n<\/div>\n
Now, let\u2019s try changing the value of key \u2018e\u2019.<\/p>\n
>>> f['e']=7\r\n>>> f<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘c’, 3), (‘e’, 7), (‘a’, 1), (‘b’, 2), (‘d’, 4)])<\/p>\n<\/div>\n
Okay. Since the key \u2018e\u2019 already exists, the old order is preserved; it isn\u2019t ordered to the end.<\/p>\n
Deleting and Reinserting a Key<\/h3>\n
When we delete a key and then reinsert it, it is ordered to the end of the new order. Let\u2019s try deleting \u2018e\u2019.<\/p>\n
>>> f.pop('e')<\/pre>\nOutput<\/strong><\/p>\n\n
7<\/p>\n<\/div>\n
>>> f<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘c’, 3), (‘a’, 1), (‘b’, 2), (‘d’, 4)])<\/p>\n<\/div>\n
Now, let\u2019s insert it again.<\/p>\n
>>> f['e']=7\r\n>>> f<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘c’, 3), (‘a’, 1), (‘b’, 2), (‘d’, 4), (‘e’, 7)])<\/p>\n<\/div>\n
As you can see, it is at the back of the list now.<\/p>\n
Popitem() in Python<\/h3>\n
The popitem() method in Python may take 0 or 1 argument- \u2018last\u2019. When \u2018last\u2019 is true, LIFO is followed to delete; otherwise, FIFO is followed. When we don\u2019t pass an argument, the last is assumed to be true.<\/p>\n
Let\u2019s take a new Python OrderedDict for this.<\/p>\n
>>> g=OrderedDict()\r\n>>> g['d']=4\r\n>>> g['b']=2\r\n>>> g['a']=1\r\n>>> g['c']=3\r\n>>> g['e']=5\r\n>>> g<\/pre>\nOutput<\/strong><\/p>\n\n
OrderedDict([(‘d’, 4), (‘b’, 2), (‘a’, 1), (‘c’, 3), (‘e’, 5)])<\/p>\n<\/div>\n
Now, let\u2019s start popping.<\/p>\n
>>> g.popitem(last=False)<\/pre>\nOutput<\/strong><\/p>\n\n
(‘d’, 4)<\/p>\n<\/div>\n
>>> g.popitem()<\/pre>\nOutput<\/strong><\/p>\n\n
(‘e’, 5)<\/p>\n<\/div>\n
>>> g.popitem(last=True)<\/pre>\nOutput<\/strong><\/p>\n\n
(‘c’, 3)<\/p>\n<\/div>\n
So, this was all about Python OrderedDict Tutorial. Hope you like our explanation.<\/p>\n
Python Interview Questions on OrderedDict<\/h3>\n
1. What is an OrderedDict in Python?<\/p>\n
2. Why use Python OrderedDict?<\/p>\n
3. How is Ordereddict implemented in Python?<\/p>\n
4. How to update Ordereddict in Python?<\/p>\n
5. Give an example of Python OrderedDict.<\/p>\n
Conclusion<\/h3>\n
Hopefully, we\u2019ve covered every important detail about Python orderedDict in this article.<\/p>\n
We saw how to define them, Syntax, deleting and reinserting, assigning A key to Python ordereddict, and we saw methods move_to_end(), popitem(), and pop().<\/p>\n
OrderedDict kept insertion order before Python 3.7 made that standard, but still offers methods like move_to_end for cache work.<\/p>\n","protected":false},"excerpt":{"rendered":"
We\u2019ve been talking about classes from the Python collections module- Python namedtuple, and Python defaultdict. Today, we base our article on Python OrderedDict, another class in \u2018collections\u2019. Here we study what Python OrderedDict is...<\/p>\n","protected":false},"author":5,"featured_media":36240,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[46],"tags":[4401,7094,9330,9560,10748,10763,11532,14093,15871],"class_list":["post-7504","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-python","tag-examples-of-python-ordereddict","tag-introduction-to-python-ordereddict","tag-ordereddict-in-python","tag-popitem-method-in-python","tag-python-ordereddict-syntax","tag-python-popitem","tag-reordering-python-ordereddict","tag-syntax-of-python-ordereddict","tag-what-is-python-ordereddict"],"yoast_head":"\n
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