What are the hashable data types in Python?

Asked Dec 05 '19 at 15:27

Active Dec 05 '19 at 15:40

Viewed 48 times

In Python, dictionaries are good to store and retrieve data. So, recently I discovered something called Hashable data types and it can be used as dictionary key values.

Below there two code snippets and first one working but the second one is not working.

I would like know what are the Hashable Data Types in Python? and How Python handles hashing basically (not the hashing algorithm but the logic beneath it)?

Code 1:

testDict = {["someArg", 35]: "someValue"}
print(testDict[["someArg", 35]])

Output 1:

 File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'list'

Code 2:

testDict = {("someArg", 35): "someValue"}
print(testDict[("someArg", 35)])

Output 2:

"someValue"

What makes Python to act different to these two iterable data types? How can I understand if a data type is Hashable or not?

I'm using Python 3.7.0.

Thanks!

edited Dec 05 '19 at 15:40

asked Dec 05 '19 at 15:27

furkanayd

1

related: https://stackoverflow.com/questions/3460650/asking-is-hashable-about-a-python-value – EdChum Dec 05 '19 at 15:29
1

Does this answer your question? [What does "hashable" mean in Python?](https://stackoverflow.com/questions/14535730/what-does-hashable-mean-in-python) – Dec 05 '19 at 15:30
you mean *hashable* types, not hash**t**able – juanpa.arrivillaga Dec 05 '19 at 15:37
@juanpa.arrivillaga Thanks. It's autocorrection. – furkanayd Dec 05 '19 at 15:41
1

I hate it when autocorrection changes a word without warning you and giving you the choice. – Mark Ransom Dec 05 '19 at 16:29

What are the hashable data types in Python?

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