Viz.Heatmap

Renders a heatmap as an SVG data URI showing data density using kernel density estimation

Kernel Density Estimation (KDE)

KDE is a statistical method that estimates the probability density function of your data by placing a "kernel" (typically a normal distribution) at each data point. The heatmap visualizes data density across the range, creating smooth gradients that reveal patterns and concentrations in your dataset.

Key Parameters:

• Samples: Controls the resolution of the density calculation (higher = smoother, but slower performance)

• Bandwidth: Controls the smoothing level - smaller values create sharper peaks around data points, larger values create broader, smoother distributions

SyntaxExampleDefinition

DaxLib.SVG.Viz.Heatmap( axisRef, measureRef, color, width, height )

Parameter	Type	Required	Description
axisRef	ANYREF EXPR		Axis reference column
measureRef	NUMERIC EXPR		Measure expression
color	STRING		Optional color for high density areas. Defaults to Power BI theme color
width	INT64		Optional: SVG width. Defaults to 120
height	INT64		Optional: SVG height. Defaults to 48

STRING SVG Heatmap

DaxLib.SVG.Viz.Heatmap(
    Products[Product],  // axisRefColumn
    [Total Cost],       // measureRefExpr
    BLANK(),            // color (uses default theme)
    200,                // width
    60                  // height
)
// Returns an SVG data URI with an embedded heatmap
// Set as a measure with DataCategory = "ImageUrl"

function 'DaxLib.SVG.Viz.Heatmap' =
        (
            axisRef: ANYREF EXPR,
            measureRef: NUMERIC EXPR,
            color: STRING,
            width: INT64,
            height: INT64
        ) =>

            VAR _W = IF( ISBLANK( width ), 120, width )
            VAR _H = IF( ISBLANK( height ), 48, height )
            VAR _Color = IF( NOT ISBLANK( color ), color, DaxLib.SVG.Color.Theme( "Power BI", 1 ) )
            VAR _Marks =
                DaxLib.SVG.Compound.Heatmap(
                    0, 0, _W, _H, 0, 0,
                    axisRef, measureRef, 50, 1, _Color
                )

            RETURN
                IF( NOT ISBLANK( _Marks ), DaxLib.SVG.SVG( "100%", "100%", "0 0 " & _W & " " & _H, _Marks, BLANK() ) )