Polynomial regression: Difference between revisions
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(Scala contribution added.) |
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<pre>[1.0, 2.0, 3.0]</pre> |
<pre>[1.0, 2.0, 3.0]</pre> |
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=={{header|Scala}}== |
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{{Out}}See it yourself by running in your browser [https://scastie.scala-lang.org/NklZH2LlScCpfsN4NSfFvA Scastie (remote JVM)]. |
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{{libheader|Scala Math Polynomial}} |
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{{libheader|Scastie qualified}} |
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{{works with|Scala|2.13}} |
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<lang Scala>object PolynomialRegression extends App { |
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private def xy = Seq(1, 6, 17, 34, 57, 86, 121, 162, 209, 262, 321).zipWithIndex.map(_.swap) |
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private def polyRegression(xy: Seq[(Int, Int)]): Unit = { |
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val r = xy.indices |
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def average[U](ts: Iterable[U])(implicit num: Numeric[U]) = num.toDouble(ts.sum) / ts.size |
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def x3m: Double = average(r.map(a => a * a * a)) |
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def x4m: Double = average(r.map(a => a * a * a * a)) |
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def x2ym = xy.reduce((a, x) => (a._1 + x._1 * x._1 * x._2, 0))._1.toDouble / xy.size |
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def xym = xy.reduce((a, x) => (a._1 + x._1 * x._2, 0))._1.toDouble / xy.size |
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val x2m: Double = average(r.map(a => a * a)) |
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val (xm, ym) = (average(xy.map(_._1)), average(xy.map(_._2))) |
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val (sxx, sxy) = (x2m - xm * xm, xym - xm * ym) |
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val sxx2: Double = x3m - xm * x2m |
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val sx2x2: Double = x4m - x2m * x2m |
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val sx2y: Double = x2ym - x2m * ym |
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val c: Double = (sx2y * sxx - sxy * sxx2) / (sxx * sx2x2 - sxx2 * sxx2) |
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val b: Double = (sxy * sx2x2 - sx2y * sxx2) / (sxx * sx2x2 - sxx2 * sxx2) |
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val a: Double = ym - b * xm - c * x2m |
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def abc(xx: Int) = a + b * xx + c * xx * xx |
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println(s"y = $a + ${b}x + ${c}x^2") |
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println(" Input Approximation") |
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println(" x y y1") |
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xy.foreach {el => println(f"${el._1}%2d ${el._2}%3d ${abc(el._1)}%5.1f")} |
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} |
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polyRegression(xy) |
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}</lang> |
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=={{header|Sidef}}== |
=={{header|Sidef}}== |
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{{trans|Ruby}} |
{{trans|Ruby}} |
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say coeff</lang> |
say coeff</lang> |
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{{out}} |
{{out}} |
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<pre> |
<pre>[1, 2, 3]</pre> |
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[1, 2, 3] |
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</pre> |
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=={{header|Stata}}== |
=={{header|Stata}}== |