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Python Introducing Dictionaries Introducing Dictionaries Recap of Introducing Dictionaries

Posted by Erik Embervine
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Erik Embervine
Python Development Techdegree Student 2,442 Points

dictionaries are ordered, or not ordered?

the first quiz question says dictionaries are not ordered. i understand dictionaries are not indexed by numbers, but that was a different quiz question. what does the first quiz question mean when it says dictionaries are not ordered?

2 Answers

Jeff Muday
MOD
Jeff Muday
Treehouse Moderator 28,720 Points
Jeff Muday
Jeff Muday
Treehouse Moderator 28,720 Points

You are indeed correct! Dictionaries are not ordered.

But, sometimes the implementation of Python you are working on will have sorting by key but it is not guaranteed to be such in all Python versions.

You can have an OrderedDicttype. (e.g. OrderedDict can be used if the code specification for your project requires "legacy" Python, that is, versions prior to 3.7.)

Read about it here:

RealPython "OrderedDict vs dict in Python: The Right Tool for the Job"

https://realpython.com/python-ordereddict

Ruby Wu
Ruby Wu
7,989 Points
Ruby Wu
Ruby Wu
7,989 Points

As of Python version 3.7, dictionaries are ordered. In Python 3.6 and earlier, dictionaries are unordered.

Jeff Muday
Jeff Muday
Treehouse Moderator 28,720 Points
Jeff Muday
Jeff Muday
Treehouse Moderator 28,720 Points

You make a good point!

You may be surprised to discover on your job, certain codebases/libraries will require legacy versions of Python. Believe it or not some companies are still using Python 2.7 because of library constraints.

It is still a best practice to use OrderedDict where the dictionaries are meant to be ordered. It is possible that this esoterica will pop up in coding interviews!

Good luck on your Python journey!