Pasha Murat wrote: > > Hi, > > if in the following macro (which has been stolen from the ROOT class manual) > I change gr->Draw("AP") into gr->Draw("A") or gr->Draw("P") nothing > happens on the screen except a segment is drawn on the right side of the canvas. > Is it a supposed behaviour? > -------------------------------------------------------------------------------- > { > gROOT->Reset(); > gStyle->SetFillColor(0); > graph = new TCanvas("graph","A Simple Graph with error bars",200,10,700,500); > > Int_t n = 10; > Float_t x[n] = {-0.22, 0.05, 0.25, 0.35, 0.5, 0.61,0.7,0.85,0.89,0.95}; > Float_t y[n] = {1,2.9,5.6,7.4,9,9.6,8.7,6.3,4.5,1}; > Float_t ex[n] = {.05,.1,.07,.07,.04,.05,.06,.07,.08,.05}; > Float_t ey[n] = {.8,.7,.6,.5,.4,.4,.5,.6,.7,.8}; > > gr = new TGraphErrors(n,x,y,ex,ey); > gr->SetTitle("TGraphErrors Example"); > gr->SetMarkerColor(1); > gr->SetMarkerStyle(20); > gr->Draw("AP"); > graph->Update(); > } > The option "A" in TGraph::Draw computes the graph range , clear the pad and draw the Axis. The statement gr->Draw("P") draws only the graph in the current pad. The reason why you see only part of the picture is that the default canvas range is [0,1] in x and y. You could have set the canvas/pad range, example: graph->Range(-0.3,-1,1.1,12); gr->Draw("P"); In this case you will see the complete graph without the axes. -------------------------------------------------------------------------------- > Another relevant question: > > I need to superimpose 2 sets of experimental points. To do this in PAW one > uses the following command sequence: > > > hplot/null ..... * define dimensions of the plot > > hplot/err .... * plot 1st set of points > > hplot/err .... * plot 2nd set of points > > What is the equivalent command sequence of ROOT commands? You can do for example: TH2F *frame = new TH2F("frame","title",2,xmin,xmax,2,ymin,ymax); frame->Draw(); gr1->Draw("lp"); gr2->Draw("lp"); > It would be very helpful to include an example of how to do this into ROOT > manual/tutorials - this is one of the very basic things people are doing. > I will add a new tutorial. Rene Brun
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