Question

I’ll start with my test using the speclj framework.

(it "turns the string into a hash-map"
  (should= {1 "1" 2 "2" 3 "3"}
    (format-string "1=1 2=2 3=3")))

Then my code:

(:use [clojure.string :only (split)])

(defn format-string [string]
  (split string #"\s+"))

Right now, the format-string function returns ["1=1" "2=2" "3=3"] and the test fails. As you can see in my test, I want it to return a hash-map with key-value pairs indicated by the = sign.

I’ve tried a few things and I’ve gotten close, but can’t quite understand how to make this transformation.

EDIT

Figured out one solution, although the keys are strings instead of integers.

My code:

(defn format-board [route]
  (let [[first second third] (split route #"\s+")]
    (merge 
      (apply hash-map (split-at-equals first))
      (apply hash-map (split-at-equals second))
      (apply hash-map (split-at-equals third))

This returns {"1" "1" "2" "2" "3" "3"}.

Answer 1

You have split at the spaces, but then you need to split again at the = delimiter. You can use regular expressions to do the parsing. Once you have your pairs you can assoc into a hash-map. Here I’ve used reduce to effect the transformation.

user=> (reduce #(assoc % (read-string (nth %2 1)) (nth %2 2)) {} 
   #_>   (re-seq #"([^=\s]+)=([^=\s]+)" "1=1 2=2 3=3") )
{3 "3", 2 "2", 1 "1"}

Note key order is not applicable to hash-maps

user=> (= {1 "1", 2 "2", 3 "3"} *1)
true