Flutter Dart - the argument type 'String' can't be assigned to the parameter type 'Map<String,dynamic>'

I need to pass 2 arguments in ChartSampleData() but I'm having trouble because it says that

List<ChartSampleData> _list = [];
_list.add(ChartSampleData.fromMap(
                '${formattedDate.toString()}', redeemedToday[index].total));

the argument type 'String' can't be assigned to the parameter type 'Map<String,dynamic>'

here's my class

i tried doing these,

Code:

class ChartSampleData {
  ChartSampleData(this.xValue, this.yValue);
  ChartSampleData.fromMap(
      Map<String, dynamic> dataMap0, Map<String, dynamic> dataMap1)
      : xValue = dataMap0['x'],
        yValue = dataMap1['y'];

  final dynamic xValue;
  final dynamic yValue;
}