TGaxis vanishes

ROOT
1

Hi ROOTers!

When drawing to a canvas i also Draw a TGaxis to the same Canvas and it vanishes somehow when Saving. I have provided some boiled down version of the programm:

import ROOT
import os
from array import array

def save(canvas,plotpath, filename,extensions = ["png", "pdf", "root"]): 
    if not os.path.exists(plotpath):
        os.makedirs(plotpath)
    for ext in extensions:
        savePath = os.path.join(plotpath,filename)
        canvas.Print("%s.%s"%(savePath,ext))

def drawObjs(canvas,objList,xMin = None,xMax = None,yMin = None,yMax = None,caption = "Spectrum", xAxis = "xAxisName", yAxis = "yAxisName",yAxis2 = None,frameBool = True,drawOptions = []):
    #yAxis2         Can be initialized like: yAxis2 = {"obj":obj,"title",title"yMin":yMin,"yMax":yMax}
    #drawOptions    Can be [[obj1,"P"],[obj3,""]]

    if frameBool:
        canvas.DrawFrame(xMin,yMin,xMax,yMax,"%s;%s;%s" % (caption,xAxis,yAxis))

    for obj,i in zip(objList,range(len(objList))):
        #Set Drawoption
        drawOption = "P"
        for drawObject,drawOptionTemp in drawOptions:
            if drawObject == obj:
                drawOption = drawOptionTemp
                break

        if not frameBool and obj == objList[0]:
            obj.Draw(drawOption)
        else:
            obj.Draw("SAME" + drawOption)

        #Second yAxis
        if not yAxis2 is None and (issubclass(obj.__class__,ROOT.TGraph) or issubclass(obj.__class__,ROOT.TF1) or issubclass(obj.__class__,ROOT.TH1)):
            if obj == yAxis2["obj"]:
                axis = ROOT.TGaxis( ROOT.gPad.GetUxmax(),
                                    ROOT.gPad.GetUymin(),
                                    ROOT.gPad.GetUxmax(),
                                    ROOT.gPad.GetUymax(),
                                    yAxis2["yMin"],
                                    yAxis2["yMax"],
                                    50510,"+L")
                axis.SetTitle(yAxis2["title"])
                axis.Draw("SAME")   #Doesnt matter if i say "same" here or not
    raw_input()
    return canvas

if __name__ == "__main__":
    xMin = -5
    xMax = 5
    hist = ROOT.TH1F("hist","hist",100,xMin,xMax)
    hist.SetMarkerStyle(2)
    gaus = ROOT.TF1("g","gaus",xMin,xMax)
    gaus.SetParameters(1,2,3)
    hist.FillRandom("g")
    canvas = ROOT.TCanvas("canvas","CAPTION",2048,1024)
    #canvas.Range(-10,-1,10,1)
    canvas = drawObjs(canvas,[gaus,hist],yAxis = "Gaus",yAxis2 = {"title":"Histo","obj":hist,"yMin":0.,"yMax":100},xMin = xMin,xMax = xMax,yMin = 0,yMax = 100)
    raw_input()
    save(canvas,"/user/tmp","Test")

Just before saving i have the canvas as wished but the right axis is gone when opening the pdf. I hope someone can solve this [-o<
Cheers,
Daniel

2

Daniel,

looks like reference counting kills it. The easiest is to add the axis as a data member to the canvas before returning, to give it the same life time as the canvas:[code]canvas._yaxis = axis[code]
HTH,
Wim

3

That helped. Thanks!!!