sort a list of maps by value of a key in descending order in clojure

Question

I have a list of maps having directory sizes as strings. I want to sort it in descending order of size: the problem is that it contains units as welL ie GB or MB

The list looks something like this:

    ({:directory_path /user/dod/1, :directory_size 8.49 MB} {:directory_path /user/dod/22, :directory_size 1.66 GB} {:directory_path /user/dod/testorc, :directory_size 1.28 MB} )

hot to sort it such that it is in decreasing order of sizes?

Answer 1

You could do:

(defn str->float [s]
  (Float. s))

(defn filesize->num [fs]
  (let [[size unit] (clojure.string/split fs #" ")
        size (str->float size)]
    (condp = unit
          "MB" size
          "GB" (* size 1000))))

(def ->ds #(-> % :directory_size filesize->num))

(defn sort-data [data]
  (sort-by ->ds #(compare %2 %1) data))

(def data [{:directory_path "/user/dod/2", :directory_size "8.49 MB"}
           {:directory_path "/user/dod/22", :directory_size "1.66 GB"}
           {:directory_path "/user/dod/testorc", :directory_size "1.28 MB"}])

(sort-data data)