Python: What's a correct and good way to implement hash()?

Posted by random-name on Stack Overflow See other posts from Stack Overflow or by random-name
Published on 2010-05-25T22:56:46Z Indexed on 2010/05/25 23:01 UTC
Read the original article Hit count: 141

Filed under:

python

|

hashtable

|

hashcode

|

dict

What's a correct and good way to implement hash()?

I am talking about the function that returns a hashcode that is then used to insert objects into hashtables aka dictionaries.

As hash() returns an integer and is used for "binning" objects into hashtables I assume that the values of the returned integer should be uniformly distributed for common data (to minimize collisions). What's a good practice to get such values? Are collisions a problem? In my case I have a small class which acts as a container class holding some ints, some floats and a string.

© Stack Overflow or respective owner

Related posts about python

unmet dependencies in Ubuntu 12.04

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I tried today to install a dvb-card on my Ubuntu 12.04 (Linux blauhai-linux 3.2.0-25-generic #40-Ubuntu SMP Wed May 23 20:30:51 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux ). The installation failed with an error. After that, i tried to install python (it was already installed but i got this error): linux:~$… >>> More
How can I get sikuli-ide to work?

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I installed sikuli-ide with sudo apt-get install sikuli-ide Everything was fine until I tried to start it from the terminal. I typed sikuli-ide But the only response I got was [info] locale: en_US The application was not started, furthermore there is no desktop file and sikuli-ide does not… >>> More
Getting PATH right for python after MacPorts install

as seen on Super User - Search for 'Super User'
I can't import some python libraries (PIL, psycopg2) that I just installed with MacPorts. I looked through these forums, and tried to adjust my PATH variable in $HOME/.bash_profile in order to fix this but it did not work. I added the location of PIL and psycopg2 to PATH. I know that Terminal is… >>> More
call python with system() in R to run a python script emulating the python console

as seen on Stack Overflow - Search for 'Stack Overflow'
I want to pass a chunk of Python code to Python in R with something like system('python ...'), and I'm wondering if there is an easy way to emulate the python console in this case. For example, suppose the code is "print 'hello world'", how can I get the output like this in R? >>> print… >>> More
Python - Calling a non python program from python?

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I am currently struggling to call a non python program from a python script. I have a ~1000 files that when passed through this C++ program will generate ~1000 outputs. Each output file must have a distinct name. The command I wish to run is of the form: program_name -input -output -o1 -o2… >>> More

Related posts about hashtable

Copy hashtable to another hashtable using c++

as seen on Stack Overflow - Search for 'Stack Overflow'
I am starting with c++ and need to know, what should be the approach to copy one hashtable to another hashtable in C++? We can easily do this in java using: HashMap copyOfOriginal=new HashMap(original); But what about C++? How should I go about it? UPDATE Well, I am doing it at a very basic level… >>> More
Search Complexity of a Hashtable within a Hashtable?

as seen on Stack Overflow - Search for 'Stack Overflow'
Say we have a hashtable of size m, and at each bucket we store a hashtable of size p. What would the worst case/average case search complexity be? I am inclined to say that since computing a hash function is still atomic, the only worst case scenario is if the value is at the end of the linked list… >>> More
How to fix the size of the Hashtable and find the whether it has fix size or not?

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi All, I am trying to fix the size of the Hashtable with following code. Hashtable hashtable = new Hashtable(2); //Add elements in the Hashtable hashtable.Add("A", "Vijendra"); hashtable.Add("B", "Singh"); hashtable.Add("C", "Shakya"); hashtable.Add("D"… >>> More
Hi, I have a C hashing routine which is behaving strangely?

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, In this hashing routine: 1.) I am able to add strings. 2.) I am able to view my added strings. 3.) When i try to add a duplicate string, it throws me an error saying already present. 4.) But, when i try to delete the same string which is already present in hash table, then the lookup_routine… >>> More
Hashtable comparator problem

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi guys i've never written a comparator b4 and im having a real problem. I've created a hashtable. Hashtable <String, Objects> ht; Could someone show how you'd write a comparator for a Hashtable? the examples i've seen overide equals and everything but i simply dont have a clue. The code… >>> More