TGraph *myGraph = new TGraph(nPoints, xValues, yValues); int numPoints = myGraph->GetN();
TCanvas *myCanvas = new TCanvas("myCanvas", "My Graph", 800, 600); TGraph *myGraph = new TGraph("myData.txt"); int numPoints = myGraph->GetN(); myCanvas->cd(); myGraph->Draw("ALP");In this example, a TCanvas object is created to display the graph. A TGraph object is then created from a data file, and the number of points in the graph are retrieved using the GetN() function. Finally, the graph is drawn on the canvas using the Draw() function, with options specified as "ALP". Overall, the TGraph GetN() function is a useful tool for working with TGraph objects in the ROOT Data Analysis Framework. It allows for easy retrieval of the number of points in a graph, which can be useful for a variety of data analysis and visualization tasks.