create map when you have a vector of keys and values

Question

I'm sure this is easy but i suspect i'll have a lot of little questions on the road to idomatic clojure. Maybe I missed something but looking at the clojure map page, I didn't find a solution.

Given two vectors (one of keys other of values) how do you efficiently (key word!) create a map from key to value?

The keys and values are below:

(:year :month :day) (core/split "2013-02-18" #"-")

Answer 1

The natural solution is to use zipmap:

(zipmap [:year :month :day] (clojure.string/split "2013-02-18" #"-"))
;= {:day "18", :month "02", :year "2013"}

For a small map like this it is actually pretty efficient. For a larger map, you'd want zipmap to use transients, which it currently doesn't. There's a ticket for that in JIRA, with my patch attached: CLJ-1005.

Of course it's simple enough to include the transient-enabled zipmap in one's own codebase and use it in preference to the one in clojure.core. This is a pretty important thing to do if you're zipping up larger maps.

The code can be copied over from the patch or from the ClojureScript core library, which does use transients in its zipmap; here a link to the ClojureScript source as of release 1844 (this particular function can be used in Clojure with no changes).

Answer 2

What you are looking for is zipmap