CODEWITHSUNDEEP
clojure
Jack Evans
Jack Evans

Reputation: 1717

Clojure order hash map by value using key name as tiebreaker

I'd like to be able to sort a hash-map by the value of it's keys, using the key name itself in the event of a tie

I have an an ordering function taken from the Clojure wiki https://clojuredocs.org/clojure.core/sorted-map-by#example-542692d5c026201cdc327094

(defn order-map [target]
  (into (sorted-map-by (fn [key1 key2]
                         (compare [(target key2) key2]
                                  [(target key1) key1]))) target))

Currently I'm able to do 

(-> "notarealroom" frequencies order-map)

which outputs

{\o 3, \r 2, \a 2, \t 1, \n 1, \m 1, \l 1, \e 1}

but I'd like to be able to sort those keys with the same value, e.g. \r and \a alphabetically to give something like the following...

{\o 3, \a 2, \r 2, \e 1, \l 1, \m 1, \n 1, \t 1}

I'm unsure how to modify the compare function to deal with this tie-break scenario

Upvotes: 0

Views: 406

Answers (1)

OlegTheCat
OlegTheCat

Reputation: 4513

You were almost there. The following should do the right thing:

(defn order-map [target]
  (into (sorted-map-by (fn [key1 key2]
                         (compare [(target key2) key1]
                                  [(target key1) key2]))) target))

Upvotes: 2

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