2D Histogram Contour in Julia

2D Histogram Contours or Density Contours

A 2D histogram contour plot, also known as a density contour plot, is a 2-dimensional generalization of a histogram which resembles a contour plot but is computed by grouping a set of points specified by their x and y coordinates into bins, and applying an aggregation function such as count or sum (if z is provided) to compute the value to be used to compute contours. This kind of visualization (and the related 2D histogram, or density heatmap) is often used to manage over-plotting, or situations where showing large data sets as scatter plots would result in points overlapping each other and hiding patterns.

2D Histograms with Graph Objects

Basic 2D Histogram Contour

using PlotlyJS, Distributions

x = rand(Uniform(-1,1), 500)
y = rand(Uniform(-1,1), 500)

plot(histogram2dcontour(x=x,y=y))

2D Histogram Contour Colorscale

using PlotlyJS, Distributions

x = rand(Uniform(-1,1), 500)
y = rand(Uniform(-1,1), 500)

plot(histogram2dcontour(x=x,y=y, colorscale="Blues"))

2D Histogram Contour Styled

using PlotlyJS, Distributions

x = rand(Uniform(-1,1), 500)
y = rand(Uniform(-1,1), 500)

plot(histogram2dcontour(
        x = x,
        y = y,
        colorscale = "Jet",
        contours = attr(
            showlabels = true,
            labelfont = attr(
                family = "Raleway",
                color = "white"
            )
        ),
        hoverlabel = attr(
            bgcolor = "white",
            bordercolor = "black",
            font = attr(
                family = "Raleway",
                color = "black"
            )
        )

))

2D Histogram Contour Subplot

using PlotlyJS

t = range(-1, stop=1.2, length=2000)
x = (t .^ 3) .+ (0.3 .* randn(2000))
y = (t .^ 6) .+ (0.3 .* randn(2000))

trace1 = histogram2dcontour(
        x = x,
        y = y,
        colorscale = "Blues",
        reversescale = true,
        xaxis = "x",
        yaxis = "y"
    )
trace2 = scatter(
        x = x,
        y = y,
        xaxis = "x",
        yaxis = "y",
        mode = "markers",
        marker = attr(
            color = "rgba(0,0,0,0.3)",
            size = 3
        )
    )
trace3 = histogram(
        y = y,
        xaxis = "x2",
        marker = attr(
            color = "rgba(0,0,0,1)"
        )
    )
trace4 = histogram(
        x = x,
        yaxis = "y2",
        marker = attr(
            color = "rgba(0,0,0,1)"
        )
    )

layout = Layout(
    autosize = false,
    xaxis = attr(
        zeroline = false,
        domain = [0,0.85],
        showgrid = false
    ),
    yaxis = attr(
        zeroline = false,
        domain = [0,0.85],
        showgrid = false
    ),
    xaxis2 = attr(
        zeroline = false,
        domain = [0.85,1],
        showgrid = false
    ),
    yaxis2 = attr(
        zeroline = false,
        domain = [0.85,1],
        showgrid = false
    ),
    height = 600,
    width = 600,
    bargap = 0,
    hovermode = "closest",
    showlegend = false
)

plot([trace1, trace2, trace3, trace4], layout)

Reference

See https://plotly.com/julia/reference/histogram2dcontour/ for more information and chart attribute options!