How to define a C++ map

Do you mean this:

/* Funtions declaration */


/*
TGraphErrors* fill_graph(Double_t* x, Double_t* y, Double_t* ex, Double_t* ey, int markerStyle, int markerColor, TMultiGraph* mg);
*/

//main
void test2()
{
	
	map<char, int> myMap = {{'A',2}, {'B', 3}};
	cout << myMap['A'] << endl;
	
	map<float, TVector<double>> data{{25.0, {14.0, 16.0, 18.0, 19.67, 21.33, 22.67}}};
	data[25.0];
	
	Double_t volts[] = {10, 20, 30, 40, 50, 60};

	TCanvas* c1 = new TCanvas("c1", "test", 640, 480);
	TGraph *graph1 = new TGraph(6, volts, data[25.0].data());
	graph1 -> Draw("ap");
}
In file included from input_line_8:1:
/mnt/d/Sync1/Desktop/test2.c:15:20: error: expected '>'
        map<float, TVector<double>> data{{25.0, {14.0, 16.0, 18.0, 19.67, 21.33, 22.67}}};
                          ^
/mnt/d/Sync1/Desktop/test2.c:16:2: error: use of undeclared identifier 'data'
        data[25.0];
        ^
/mnt/d/Sync1/Desktop/test2.c:21:40: error: use of undeclared identifier 'data'
        TGraph *graph1 = new TGraph(6, volts, data[25.0].data());
                                              ^

Not sure how to build a TVector