Summaries

Intro

Summaries is a clojure/clojurescript library without external dependencies for enriching a nested data structure with data derived from the existing data in the structure.

Usage

To use Summaries in an existing project, you can add this to your dependencies in your project.clj:

Build status

An example

You have data about a classical orchestra. There are musicians with wood, brass and strings instruments. The following represents the data in a clojure map.

(def orchestra
  {:conductor "Leonard B."
   :musician
   [{:name "Morten K."
     :experience-level 7
     :instrument-class 'brass
     :instrument-type 'trumpet
     :venues ["hollywood bowl"
              "royal arena"]}
    {:name "Anders T."
     :experience-level 8
     :instrument-class 'brass
     :instrument-type 'french-horn
     :venues ["sydney opera house"
              "royal arena"]}
    {:name "Melanie C."
     :experience-level 4
     :instrument-class 'wood
     :instrument-type 'oboe
     :venues ["recife"]}
    {:name "Trine T."
     :experience-level 2
     :instrument-class 'wood
     :instrument-type 'clarinet
     :venues []}
    {:name "Kurt H."
     :experience-level 5
     :instrument-class 'strings
     :instrument-type 'violin
     :venues ["bourla"]}
    {:name "Mikkel G."
     :experience-level 9
     :instrument-class 'strings
     :instrument-type 'cello
     :venues ["aarhus musikhus"]}]})

You would now like to enrich this data with some fields. You need the average experience level for musicians using wood instruments, the set of venues that musicians have played at, and per musician the amount of venues he or she has played. The following data structures describe tasks that summaries can execute.

(def avg-experience-wood
  {:operation 'avg
   :input-path [:musician* ['= :instrument-class 'wood] :experience-level]
   :insert-path [:summaries :avg-experience-wood]})

(def amount-venues-per-musician
  {:operation 'count
   :start-path [:musician*]
   :input-path [:venues*]
   :insert-path [:amount-venues]})

(def unique-venues-across-musicians
  {:operation 'unique
   :input-path [:musician* :venues*]
   :insert-path [:summaries :venues]})

You can now reduce to the desired result, using the apply-summary function.

(reduce (fn [acc task]
          (apply-summary task acc))
        orchestra
        [avg-experience-wood
         amount-venues-per-musician
         unique-venues-across-musicians])

;==>
{:conductor "Leonard B.",
 :musician
 [{:name "Morten K.",
   :experience-level 7,
   :instrument-class brass,
   :instrument-type trumpet,
   :venues ["hollywood bowl" "royal arena"],
   :amount-venues 2}
  {:name "Anders T.",
   :experience-level 8,
   :instrument-class brass,
   :instrument-type french-horn,
   :venues ["sydney opera house" "royal arena"],
   :amount-venues 2}
  {:name "Melanie C.",
   :experience-level 4,
   :instrument-class wood,
   :instrument-type oboe,
   :venues ["recife"],
   :amount-venues 1}
  {:name "Trine T.",
   :experience-level 2,
   :instrument-class wood,
   :instrument-type clarinet,
   :venues [],
   :amount-venues 0}
  {:name "Kurt H.",
   :experience-level 5,
   :instrument-class strings,
   :instrument-type violin,
   :venues ["bourla"],
   :amount-venues 1}
  {:name "Mikkel G.",
   :experience-level 9,
   :instrument-class strings,
   :instrument-type cello,
   :venues ["aarhus musikhus"],
   :amount-venues 1}],
 :summaries
 {:avg-experience-wood 3.0,
  :venues
  ["recife"
   "sydney opera house"
   "royal arena"
   "hollywood bowl"
   "aarhus musikhus"
   "bourla"]}}

Notice how the start-path enables summaries to inject data several places in the original data structure in one go.

Running tests in Clojurescript

clj -C:test -A:cljs-test

Acknowledgements

The code as provided was produced by

• Kurt Heyrman
• Mikkel Gravgaard
• Bastian Buhrkall

Copyright UFST (see LICENSE).