Clojurians Log v2

I'm hoping to find a cljs equivalent of Underscore's "indexBy" http://underscorejs.org/#indexBy . Would anyone be able to point me in the right direction?

group-by

?

given a list of json objects, if I group by a key (say: id), the value will be a list correct?

group-by returns a map.

and the values are lists, correct.

technically a vector.

ideally I would have (group-by :id items) => {:1 {:title "title here" :description "description here"} :2 {:title "another title" ....}

Maybe something like this then?

(into {} (map (juxt :age identity) [{:name "moe" :age 40} {:name "larry" :age 50} {:name "curly" :age 60}]))

juxt is a too clever way of saying "make me a vector of results of applying those functions to something"

that works perfectly! I'll have to look into juxt now

juxt ftw

thanks @jaen @jstew

(that is in this case it is equivalent to (fn [map] [(:age map) (identity map)]))

(map (juxt inc dec) [1 2 3]) ;; ([2 0] [3 1] [4 2])

That's clever. I need to use juxt more often.

source: https://github.com/clojure/clojure/blob/clojure-1.7.0/src/clj/clojure/core.clj#L2445

That said, depending on how you use it later, you could just use group-by and just destructure on that, for example:

(for [[id [val & _]] (group-by :age [{:name "moe" :age 40} {:name "larry" :age 50} {:name "curly" :age 60}])]
      (println "id=" id "; val=" val))

So you won't have to write your own function then

looks like clojuredocs beat us to it http://clojuredocs.org/clojure.core/juxt#example-542692cfc026201cdc326e12

I noticed that but it's slightly different than the data structure that underscore returns

Swear I didn't see that before ; d

{:key {:map "map"}} vs {:key [{:map1 "map1"}]}

Does it? The first is indexBy, the second is groupBy.

Yep, you're right jaen. There is a groupBy that returns the same thing.