On Sep 8, 2006, at 10:23 AM, jbv wrote:
I created keys in an array in the following order : 1 4 5 11 52 500 555 "the keys of myArray" outputs this : 1 11 4 500 5 555 52 then I created the same keys but in reverse order : 555 500 52 11 5 4 1 and "the keys of myArray" outputs this : 1 11 4 5 500 52 555 if anyone sees any logic in the above, please let me know...
I think Richard described it. He seems to have some "inside" knowledge that a hash table is used. The above data is consistent with that.
In your example, it looks like 5 hash buckets are used: (1), (11), (4), (5, 500), and (52,555). Within each bucket, the order is based on history and is in reverse order of creation and thus the key- element pairs are probably stored in a linked list. It looks like the first character has a strong influence on the hash.
If this is really the case--who knows?--then we can guess how lookup works. Looking up "11" means going to the second nonempty bucket based on the hash. The list there has only one item. The key is confirmed and the item is returned. Looking up "500" involves going to the 4th nonempty bucket quickly based on the hash. Then each key in the list is checked. The first one ("5") fails, but the second one matches and the value is returned.
On creating the list of keys, rev might go through all the buckets and within each bucket go through all the pairs in the list. This is consistent with the above output.
Of course, this model could be wrong. If you are curious you might be able to run some experiments to see how that works. Maybe you can figure out the number of buckets. Maybe timing experiments can help.
But that should be for curiosity sake only. The order of "the keys" is not defined by Revolution and could change as the engine changes. This could be for subtle reasons; this might change because of a change in an underlying library.
If you are interested in order rather than random access, maybe you need to make a list of keys. If you need pairs, make a line list and each line can consist of two items.
By not giving your sort order or build order, the implementers are free to optimize how the array works.
Dar Scott _______________________________________________ use-revolution mailing list use-revolution@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-revolution
