Hi, The following example shows how to reverse an axis. But the data set is not reversed in that case. To do this, I think you should created a temporary "reversed version" of your data along Y (something like Ymax-y) and plot them instead of the original data. Cheers, Olivier reverseaxis () { TH2F *hpxpy = new TH2F("hpxpy","py vs px",40,-4,4,40,-4,4); Float_t px, py; TRandom r; for (Int_t i = 0; i < 25000; i++) { r.Rannor(px,py); hpxpy->Fill(px,py); } TCanvas *c1 = new TCanvas("c1"); hpxpy->Draw("colz"); ReverseXAxis(hpxpy); } ReverseXAxis (TH1 *h) { // Remove the current axis h->GetXaxis()->SetLabelOffset(999); h->GetXaxis()->SetTickLength(0); // Redraw the new axis gPad->Update(); TGaxis *newaxis = new TGaxis(gPad->GetUxmax(), gPad->GetUymin(), gPad->GetUxmin(), gPad->GetUymin(), h->GetXaxis()->GetXmin(), h->GetXaxis()->GetXmax(), 510,"-"); newaxis->SetLabelOffset(-0.03); newaxis->Draw(); } On Tue, 20 Jul 2004, Dorota Szczygiel wrote: > Hi! > I have a problem of this kind: > I need to draw y-axis upside down (bigger values lower > than smaller values), but not only rotate the axis, > also data points must change their place, according to > new y-axis values. > > Eg: Should change to: > > /|\ /|\ > 9 | . 7 | . . > | . . ---> | . . > 7 | . . 9 | . > |_________ |__________ > > > > Thanks, > Dorothy > > -- Org: CERN - European Laboratory for Particle Physics. Mail: 1211 Geneve 23 - Switzerland Mailbox: J25910 E-Mail: Olivier.Couet@cern.ch Phone: +41 22 7676522 WWW: http://cern.ch/Olivier.Couet/ Fax: +41 22 7677155
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