First time using DataScript

[Alan Thompson]

Hi - I was answering a question on StackOverflow, and after solving it using functions from clojure.core, I thought it was the  prefect candidate for a little DataScript.  Basically the user wants to do a "natural join" on column :obs/A, then print out pairs of :obs/value from type :x and type :y.  The DataScript version removes a lot of tedious, manual indexing, filtering, unification, etc.

(ns clj.core

  (:require [tupelo.core :as t] 

            [datascript.core :as d]

            [clojure.set :as set] ))

(t/refer-tupelo)

(def data

  [ {:type :x :local/id 1,   :obs/A "11",    :obs/value 2.0,    :obs/color "yellow"}

    {:type :x :local/id 2,   :obs/A "12",    :obs/value 4.0,    :obs/color "blue"}

    {:type :x :local/id 3,   :obs/A "13",    :obs/value 3.0,    :obs/color "green"}

    {:type :x :local/id 3,   :obs/A "15",    :obs/value 7.0,    :obs/color "red"} 

    {:type :y :local/id 2,   :obs/A "11",    :obs/value 7.0,    :obs/shape "square"}

    {:type :y :local/id 2,   :obs/A "13",    :obs/value 4.0,    :obs/shape "circle"}

    {:type :y :local/id 6,   :obs/A "15",    :obs/value 3.0,    :obs/shape "triangle"} ] )

(newline) (println "data") (pretty data)

(def conn (d/create-conn {}))

(d/transact! conn data)

(def labelled-result

  (d/q '[:find ?a ?value1 ?value2

             :where 

               [?ex :type :x] [?ex :obs/A ?a] [?ex :obs/value ?value1]

               [?ey :type :y] [?ey :obs/A ?a] [?ey :obs/value ?value2]

            ] @conn ))

(newline) (println "labelled-result") (pretty labelled-result)

(defn -main [& args] )

​With the result:

​

data

[{:type :x,

  :local/id 1,

  :obs/A "11",

  :obs/value 2.0,

  :obs/color "yellow"}

 {:type :x,

  :local/id 2,

  :obs/A "12",

  :obs/value 4.0,

  :obs/color "blue"}

 {:type :x,

  :local/id 3,

  :obs/A "13",

  :obs/value 3.0,

  :obs/color "green"}

 {:type :x, :local/id 3, :obs/A "15", :obs/value 7.0, :obs/color "red"}

 {:type :y,

  :local/id 2,

  :obs/A "11",

  :obs/value 7.0,

  :obs/shape "square"}

 {:type :y,

  :local/id 2,

  :obs/A "13",

  :obs/value 4.0,

  :obs/shape "circle"}

 {:type :y,

  :local/id 6,

  :obs/A "15",

  :obs/value 3.0,

  :obs/shape "triangle"}]

labelled-result

#{["13" 3.0 4.0] ["11" 2.0 7.0] ["15" 7.0 3.0]}

Cool stuff.

Alan​

[Nikita Prokopov]

Alan, 👍