| Re: Avoiding multiple or complex WHEREs? [message #75220] |
Mon, 21 February 2011 13:55  |
cgguido
Messages: 195
Registered: August 2005
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Senior Member |
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On Feb 21, 3:46 pm, Paulo Penteado <pp.pente...@gmail.com> wrote:
> On Feb 21, 6:34 pm, Gianguido Cianci <gianguido.cia...@gmail.com>
> wrote:
>
>> Ah! I think I just discovered a use for !NULL, it would fit NaN better
>> here!
>
> !null is an undefined variable. It cannot be an element of an array of
> floats or doubles. It can be come where a variable can be, such as a
> list or map element, or a pointer target.
Yeah :-/ I guess I am trying to build something like a HASH with two
keys for each value... but I could be going about this completely
backwards!
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| Re: Avoiding multiple or complex WHEREs? [message #75308 is a reply to message #75220] |
Tue, 22 February 2011 08:29  |
penteado
Messages: 866
Registered: February 2018
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Senior Member
Administrator |
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On Feb 21, 6:55 pm, Gianguido Cianci <gianguido.cia...@gmail.com>
wrote:
> Yeah :-/ I guess I am trying to build something like a HASH with two
> keys for each value... but I could be going about this completely
> backwards!
It depends on how you are going to use it, but this problems suggests
to me making a class that overloaded the brackets, to search for what
you want, and return !null if not found. Internally it could use
hashes, lists or arrays (of values or pointer arrays). The better
choice depends on things like the number of points and whether they
form a grid in ID, whether Ts are integers (I am guessing that
particle IDs are). That way it would be usable doing things like
p_cool=p[[1,3,4],23:100]
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