How to get ID of an element inputting its coordinates?

I have been looking for a not too greedy solution to this problem and i could not find any.

I have an array giving for a given element(using ID) its coordinates:

(ID X Y Z)
(12 1 2 3)
(7  2 4 5)
(4  4 9 7)

How, please, could i do this since i am computing this operation on thousands points and repetitively?

Thank you and have a nice weekend.

Arthur

[Walter Roberson]

Will all the coordinates involved be integral? Will there always be an exact match, or will it be necessary to find the closest match?