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how to access a large datastructure efficiently?
From: |
Christian Wittern |
Subject: |
how to access a large datastructure efficiently? |
Date: |
Thu, 4 Mar 2010 01:50:24 +0000 (UTC) |
User-agent: |
Loom/3.14 (http://gmane.org/) |
Hi there,
Here is the problem I am trying to solve:
I have a large list of items which I want to access. The items are in
sequential order, but many are missing in between, like:
(1 8 17 23 25 34 45 47 50) [in reality, there is a value associated
with this, but I took it out for simplicity]
Now when I am trying to access with a key that is not in the list, I
want to have the one with the closest smaller key returned, so for 6
and 7 this would be 1, but for 8 and 9 this would be 8.
Since the list will have thousands of elements, I do not want to simply
loop through it but am looking for better ways to do this in Emacs lisp.
Any ideas how to achieve this?
Christian