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clojurehashmap

How to create this hashmap?

Basically what I'm trying to do is print a hashmap that contains keys that are characters in a string, and these keys have value 1. For example, string "aabbce" should give a dictionary {:a 1 :b 1 :c 1}. The following is my attempt but it just prints the empty hashmap

(defn isValid [s]
    (def dict {})

    (map (fn [x] ((assoc dict :x 1))) (seq s))

    (println dict)

)
Solution 
  • > (into {} (for [c "aabbce"] [(keyword (str c)) 1]))
{:a 1, :b 1, :c 1, :e 1}

    into {} ... sequence of pairs ... is often a convenient way to create hashmaps. For example 

    > (into {} [[:x 1] [:y "foo"]])
{:x 1, :y "foo"}

    and for [item collection] [(key-from item) (value-from item)] can be a nice way to iterate over a collection to create that list of key-value pairs.

    > (for [color ["red" "blue" "green"]] [(clojure.string/upper-case color) (count color)])
(["RED" 3] ["BLUE" 4] ["GREEN" 5])

    I find that putting those together is often the trick for when I want to create a hashmap:

    > (into {} (for [color ["red" "blue" "green"]] [(clojure.string/upper-case color) (count color)]))
{"RED" 3, "BLUE" 4, "GREEN" 5}