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Simple Hashtable - Repackaged

version 1.1 (3.5 KB) by

Simple hashtable class repackaged in the new matlab class format.

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This is basically a repackage of the old "Simple Hashtable" by Matthew Krauski, in the new style of matlab classes. The only thing that has changed is that now the class is a handle, and I included some minor fixes to the original code. e.g. type checking that the keys inputed are really strings.

If you want to get a basic feeling of how to use the Hashtable class, look at the included file "hash_test.m" .

Notes:
a) As Ryan Rifkin noted, this isn't a Hashtable at all, this is a lookup table. But in order not to shadow simulink's builtin lookup table i left the class name as Hashtable.
b) I'll quote Ryan Rifkin again : "A good lookup table in Matlab is a very useful thing to have, but a hashtable implies some effort to provide O(1) access times --- this code simply does a string comparison on all the keys, and is therefore O(n). It's great for small tables, but it doesn't scale too well"
c) Some have noted that it is possible to use java's builtin "java.util.Hashtable" instead. But note that java's hastable does not allow you to use user made matlab classes as data. The advantage of this implementation is that it allows you to use classes as data, and that you can save and load it to disk without a problem.

Methods:
Clear - Clear hash table
Elements - Get all hash table elements
Get - Get data from the hash table
Hashtable - Constructor for Hashtable class
IsEmpty - Check to see if the hash is empty
IsKey - Check to see if the hash is currently using a key
Keys - Get all the keys currently being used in the hash
Put - Put data in the hash table
Remove - Remove element from the hash
Values - Get all data contained in the hash table

Comments and Ratings (1)

Cris Luengo

Cris Luengo (view profile)

The only advantage over a MATLAB standard `struct` is that your keys can have spaces and other non-alphanumeric characters in them. I'm not sure how valuable and important that is. Especially considering you give up the possibility to make it into an array. And I'm assuming the struct scales better with the number of keys.
But the code is well written. :)

Updates

1.1

Added a text description file to the package

MATLAB Release
MATLAB 7.8 (R2009a)
Acknowledgements

Inspired by: Simle Hashtable

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