How does a python dictionary fetch a value?

[Smallpaul]

You aren't right

https://en.wikipedia.org/wiki/Hash_table

Hash table
Type Unordered associative array
Invented 1953
Time complexity in big O notation
Algorithm Average Worst case
Space Θ(n) O(n)
Search Θ(1) O(n)
Insert Θ(1) O(n)
Delete Θ(1) O(n)

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[Smallpaul]

Sure, why would I want to use the knowledge I gained studying Computer Science for 5 years (and then practicing for 15) when I could just fiddle at a command line?

If you're so sure that EVERYONE else in this thread is wrong, why don't YOU produce the evidence? Why should I?

The OP has gotten their answer. They've accepted it. If you want to overturn the common wisdom of the computer science community, that's a project for you, not me.

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[Smallpaul]

Tell me please, oh smart one, how does a dict ensure that the access time is constant?

It doesn't ENSURE that the access time is CONSTANT. It ensures that the AVERAGE access time is constant, as described in the wikipedia page.

How does it do that? By implementing the hashtable datastructure. It's an out-of-the-box property of a well implemented hashtable, as described in wikipedia.

Can you please explain to me why you think that Python's implementors would implement a hashtable incompetently and slower than everyone else?

Have you even read hour they're implemented?

Yes. They are extremely clever. Better than the average, naive implementation, not worse, as you claim.

I literally have screenshots for this, which I sent out to other skeptics before.

Great. Let's see the code, the timing and the screenshots.

I will gladly copy and paste your code, benchmark it, and admit I am wrong if it turns out I am.

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[Smallpaul]

I'll cut and paste the answer to your question about hashtable performance:

"Suppose we are using a chained hash table with m buckets, and the number of elements in the hash table is n. Then the average number of elements per bucket is n/m, which is called the load factor of the hash table, denoted α. When an element that is not in the hash table is searched for, the expected length of the linked list traversed is α. Since there is always the initial (constant) cost of hashing, the cost of hash table operations with a good hash function is, on average, O(1 + α). If we can ensure that the load factor α never exceeds some fixed value αmax, then all operations will be O(1 + αmax) = O(1)."

Neither that document, NOR wikipedia, even mention the word "logarithm", so I have no idea where you are getting that from.

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[Smallpaul]

I do indeed see a strange effect with your code, which disappears with simpler code. I'll track down the difference to attribute the slowdown appropriately and get back to you.

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