Custom plot markers in DistributionChart

Question

I would like to use the ChartElementFunction option of DistributionChart to plot data with a custom style that includes custom plot markers, such as open circles. I am struggling with the scaling of the markers, though.

If I use Points as plot markers, everything is fine:

data = Table[RandomReal[i + {1, 3}, 10], {i, 5}];

cef1[{{xmin_, xmax_}, {ymin_,ymax_}}, data_, metadata_]:=
    {Black, PointSize[Large], Point[{RandomReal[{xmin, xmax}], #}]& /@ data};

DistributionChart[data, ChartElementFunction -> cef1]

If I use Circles, they are affected by the aspect ratio of the plot and shown as ellipses:

cef2[{{xmin_, xmax_}, {ymin_, ymax_}}, data_, metadata_] := 
    {Black, Circle[{RandomReal[{xmin, xmax}], #}, 0.05]& /@ data};

DistributionChart[data, ChartElementFunction -> cef2]

Is there a way to get the scaling right, for example make the markers behave like PlotMarkers in ListPlot?

Answer 1

Use Offset to set the radius in printer points:

cef2[{{xmin_, xmax_}, {ymin_, ymax_}}, data_, metadata_] := {Black, 
   Circle[{RandomReal[{xmin, xmax}], #}, Offset[3]] & /@ data};

DistributionChart[data, ChartElementFunction -> cef2]

You can make the radius an argument of the chart element function:

cef2b[radius_: 3][{{xmin_, xmax_}, {ymin_, ymax_}}, data_, metadata_] := {Black, 
   Circle[{RandomReal[{xmin, xmax}], #}, Offset[radius]] & /@ data};

DistributionChart[data, ChartElementFunction -> cef2b[]]

same picture

Alternatively, you can use Inset[Graphics[Circle[]],...] to make the glyph:

cef2c[size_: .025][{{xmin_, xmax_}, {ymin_, ymax_}}, data_, metadata_] := {Black, 
   Inset[Graphics @ Circle[], {RandomReal[{xmin, xmax}], #}, Automatic, 
       Scaled[size]] & /@ data};

DistributionChart[data, ChartElementFunction -> cef2c[.05], AspectRatio -> 1/2]

Use ChartElementFunction -> cef2c[.1] to get