Diving into Breeze

Let's get started. We will work in the Scala console, but a program similar to this example is available in BreezeDemo.scala in the examples corresponding to this chapter. Create a build.sbt file with the following lines:

scalaVersion := "2.11.7"

libraryDependencies ++= Seq(
  "org.scalanlp" %% "breeze" % "0.11.2",
  "org.scalanlp" %% "breeze-viz" % "0.11.2",
  "org.scalanlp" %% "breeze-natives" % "0.11.2"
)

Start an sbt console:

$ sbt console

scala> import breeze.linalg._
import breeze.linalg._

scala> import breeze.plot._
import breeze.plot._

scala> import breeze.numerics._
import breeze.numerics._

Let's start by plotting a sigmoid curve, . We will first generate the data using Breeze. Recall that the linspace method creates a vector of doubles, uniformly distributed between two values:

scala> val x = linspace(-4.0, 4.0, 200)
x: DenseVector[Double] = DenseVector(-4.0, -3.959798...

scala> val fx = sigmoid(x)
fx: DenseVector[Double] = DenseVector(0.0179862099620915...