Changing radius and color in scatter plot flutter

Question

I have this basic scatter plot and I am trying to modify some of the dots radiuses and color.
I use the charts_flutter package, and according to their docs\examples there should be a colorFn and a radiusPxFn attributes to the charts.Series object.

This is the relevant code I have written so far:

class VennDiagramWidget extends StatefulWidget {
  @override
  _VennState createState() => _VennState();
}

class _VennState extends State<VennDiagramWidget> {
  List<charts.Series<VennCircle, int>> circlesList;

  static List<charts.Series<VennCircle, int>> _createRandomCircles() {
    final circles = [
      VennCircle(1, 5, 0.8, 'Venn1'),
      VennCircle(2, 10, 0.5, 'Venn2'),
      VennCircle(3, 20, 1, 'Venn3'),
    ];

    return [
      new charts.Series(
          id: 'Circles',
          data: circles,
          domainFn: (VennCircle venn, _) => venn.circleSize,
          measureFn: (VennCircle venn, _) => venn.opacity),
          colorFn:
    ];
  }

  scatterPlot() {
    return charts.ScatterPlotChart(
      circlesList,
      animate: true,
    );
  }

When I type colorFn inside charts.Series I get an error of undefined name (same goes for radiusPxFn)

Is there another way to modify the size and color attributes? Am I doing something wrong here?

Answer 1

It seems that colorFn is placed outside Series constructor. It should be:

return [
  new charts.Series(
      id: 'Circles',
      data: circles,
      domainFn: (VennCircle venn, _) => venn.circleSize,
      measureFn: (VennCircle venn, _) => venn.opacity,
      colorFn: (VennCircle venn, _) => charts.ColorUtil.fromDartColor(Colors.green),
      radiusPxFn: (VennCircle venn, _) => venn.circleSize
  )
];