In [1]:

%useLatestDescriptors
%use lets-plot

@file:DependsOn("org.apache.commons:commons-math3:3.6.1")

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import org.apache.commons.math3.distribution.MultivariateNormalDistribution

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val cov0 : Array<DoubleArray> = arrayOf(doubleArrayOf(1.0, -.8),
                                        doubleArrayOf(-.8, 1.0))

val cov1 : Array<DoubleArray> = arrayOf(doubleArrayOf(1.0, .8),
                                        doubleArrayOf(.8, 1.0))

val cov2 : Array<DoubleArray> = arrayOf(doubleArrayOf(10.0, .1),
                                        doubleArrayOf(.1, .1))

In [4]:

val n = 400

val means0 : DoubleArray = doubleArrayOf(-2.0, 0.0)
val means1 : DoubleArray = doubleArrayOf(2.0, 0.0)
val means2 : DoubleArray = doubleArrayOf(0.0, 1.0)

val xy0 = MultivariateNormalDistribution(means0, cov0).sample(n)
val xy1 = MultivariateNormalDistribution(means1, cov1).sample(n)
val xy2 = MultivariateNormalDistribution(means2, cov2).sample(n)

In [5]:

val data = mapOf(
    "x" to (xy0.map { it[0] } + xy1.map { it[0] } + xy2.map { it[0] }).toList(),
    "y" to (xy0.map { it[1] } + xy1.map { it[1] } + xy2.map { it[1] }).toList()
)

In [6]:

val p = letsPlot(data) {x="x"; y="y"} + ggsize(600,300) +
        geomPoint(color="black", alpha=.1)
p

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In [7]:

// Basic density 
p + geomDensity2D(color="red")

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In [8]:

// Set contour color by level
//  - change defailt position and size of colorbar
p + geomDensity2D {color="..level.."} +
    scaleColorGradient(low="dark_green", high="yellow", guide=guideColorbar(barHeight=10, barWidth=300)) +
    theme().legendPositionBottom()

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Filling contours by level¶

In [9]:

val p1 = letsPlot(data) {x="x"; y="y"} + ggsize(600,300)

// Filled polygons are not always working well - note missing polygons in the middle. 
p1 + geomPolygon(stat=Stat.density2D()) {fill="..level.."} + coordFixed()

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In [10]:

// 'geomDensity2DFilled' is not dependent on poligons order and works a lot better
p1 + geomDensity2DFilled {fill="..level.."}

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geomBin2D is another way to plot density¶

In [11]:

p1 + geomBin2D()

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In [12]:

// Adjust the tile size - make them square and bigger.
// Show density instead of count.
p1 + geomBin2D(binWidth=1 to 1) {fill="..density.."}

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