Re: Red black trees and other data structures (Simon Strobl)

[Jose Santos]

In order to use the red-black trees module in Yap you must do:

:- use_module(library(rbtrees)).

(have a look at .pl files in directory /library from the Yap installation for all the possible libraries)
The manual should be updated to mention that the library must be loaded with this command (for all the other libraries the filename is available)

Kind regards,

Jose

 

Hello,

I want to use one of Yap's data structures to store large amounts of data
(such as frequency lists for strings).

I have two questions concerning this:

(1) How can I use red-black trees? The manual says a lot of things about
them, e.g. that a new red-black tree can be created with rb_new(T), but it
doesn't say which module to load.

I tried:

use_module(library(rb)).
use_module(library(redblack)).
use_module(library(redblacktrees)).

and many other names, but none of them worked.

(2) My main concern is memory efficency, i.e. the less memory a solution
needs the better. Which data structure should I use?

Simon
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[Simon Strobl]

> In order to use the red-black trees module in Yap you must do:

> :- use_module(library(rbtrees)).

Thanks.

I would like to try to state my other question more clearly:

Suppose I have a lot (e.g. several hundreds of Gigabyte) of facts of this form:

frequency('Aachen', 1234).
frequency('Aalen', 2345).
frequency('Berlin', 121212).
frequency('Baden Baden', 1218).

I suppose that I could save memory, if I put the words that are at the first argument place above into a prefix tree. (Is this correct?). But I do not see how I could use Yap's tries in such a way that the second argument can also be stored and looked up using the trie. What I want is something like:

?- search_tree_lookup('Aachen', Frequency).
Frequency = 1234.
yes

What structure should search_tree_lookup/2 use? Can it be done with tries?

Simon