-- geometry fundamentals

sandbox/src/main/scala/geometry/GeometryFundamentals.scala

@@ -0,0 +1,15 @@
+package geometry
+
+trait GeometryFundamentals {
+
+  def sq(x: Int): Int = x * x
+
+  def distance(d1: Int, d2: Int, d3: Int): Double = math.sqrt(sq(d1) + sq(d2) + sq(d3))
+
+  def isNat(x: Double): Option[Int] = Option(x.toInt).filter(_.toDouble == x)
+
+  def distanceIsNat(d1: Int, d2: Int, d3: Int): Option[Int] = isNat(distance(d1, d2, d3))
+
+}
+
+object GeometryFundamentals extends GeometryFundamentals

sandbox/src/main/scala/geometry/GeoPlayground.scala → sandbox/src/main/scala/geometry/GeometryPlayground.scala

@@ -4,9 +4,8 @@ import cats.implicits.catsSyntaxTuple3Semigroupal
 import common.Base
 import org.scalacheck.Gen
 
-class GeoPlayground extends Base {
+class GeometryPlayground extends Base with GeometryFundamentals {
 
-  /** int generator 0 to 10 */
   val intG: Gen[Int] = Gen.choose[Int](0, 9)
 
   case class Pt(x: Int, y: Int, z: Int)
@@ -17,17 +16,14 @@ class GeoPlayground extends Base {
   override implicit val generatorDrivenConfig: PropertyCheckConfiguration =
     PropertyCheckConfiguration(20)
 
-  def sq(x: Int): Int = x * x
-
   def distance(pt1: Pt, pt2: Pt): Double =
-    math.sqrt(sq(pt1.x - pt2.x) + sq(pt1.y - pt2.y) + sq(pt1.z - pt2.z))
+    distance(pt1.x - pt2.x, pt1.y - pt2.y, pt1.z - pt2.z)
 
   def next(pt: Pt, distance: Int): Option[Pt] = ???
 
   test("1") {
 
     forAll { (pt1: Pt, pt2: Pt) =>
-
       println(pt1 -> pt2 -> distance(pt1, pt2))
     }
 

sandbox/src/main/scala/geometry/NaturalDistances.scala

@@ -0,0 +1,33 @@
+package geometry
+
+import common.Base
+
+class NaturalDistances extends Base with GeometryFundamentals {
+
+  def range(min: Int, count: Int) = LazyList.from(min).take(count)
+
+  /** triplets with natural distances */
+  def genNatTriplets(min: Int = 0, count: Int = 100) = {
+    val r = range(min, count)
+    r.flatMap { d1 =>
+      r.flatMap { d2 =>
+        r.flatMap { d3 =>
+          distanceIsNat(d1, d2, d3)
+            .filter(_ < 30) // filter distance
+            .map(d => (d1, d2, d3) -> d)
+        }
+      }
+    }
+  }
+
+  test("triplets") {
+    genNatTriplets()
+      .foreach(x => println(x))
+  }
+
+  test("isNat") {
+    Seq(3.123, 3.987, 3.0)
+      .foreach(x => pprint.log(isNat(x)))
+  }
+
+}