Next: , Previous: Table Operations, Up: Relational Database


6.1.3 Database Interpolation

(require 'database-interpolate)

Indexed sequential access methods allow finding the keys (having associations) closest to a given value. This facilitates the interpolation of associations between those in the table.

— Function: interpolate-from-table table column

Table should be a relational table with one numeric primary key field which supports the isam-prev and isam-next operations. column should be a symbol or exact positive integer designating a numerically valued column of table.

interpolate-from-table calculates and returns a value proportionally intermediate between its values in the next and previous key records contained in table. For keys larger than all the stored keys the value associated with the largest stored key is used. For keys smaller than all the stored keys the value associated with the smallest stored key is used.