Editing Associative array (section)

==== Other trees ====
Associative arrays may also be stored in unbalanced [[binary search tree]]s or in data structures specialized to a particular type of keys such as [[radix tree]]s, [[trie]]s, [[Judy array]]s, or [[van Emde Boas tree]]s, though the relative performance of these implementations varies. For instance, Judy trees have been found to perform less efficiently than hash tables, while carefully selected hash tables generally perform more efficiently than adaptive radix trees, with potentially greater restrictions on the data types they can handle.<ref>{{Cite book|last1=Alvarez|first1=Victor|last2=Richter|first2=Stefan|last3=Chen|first3=Xiao|last4=Dittrich|first4=Jens|title=2015 IEEE 31st International Conference on Data Engineering |chapter=A comparison of adaptive radix trees and hash tables |date=April 2015|location=Seoul, South Korea|publisher=IEEE|pages=1227–1238|doi=10.1109/ICDE.2015.7113370|isbn=978-1-4799-7964-6|s2cid=17170456}}</ref> The advantages of these alternative structures come from their ability to handle additional associative array operations, such as finding the mapping whose key is the closest to a queried key when the query is absent in the set of mappings.