[hist] Use WW comparison when TH1::Chi2Test is invoked with TProfiles.

The test can only work if the uncertainties are taken into account
correctly, so the Chi2Test function was overridden for all TProfile
classes.
Furthermore, the function will check if the profiles have the correct
error option set.

See also the discussion in:
https://root-forum.cern.ch/t/chi2test-using-tprofile/64156/

Author: hageboeck

hist/hist/inc/TProfile.h

@@ -89,7 +89,8 @@ class TProfile : public TH1D {
    Bool_t   Add(const TH1 *h1, const TH1 *h2, Double_t c1=1, Double_t c2=1) override; // *MENU*
    static  void     Approximate(Bool_t approx=kTRUE);
    Int_t    BufferEmpty(Int_t action=0) override;
-           void     BuildOptions(Double_t ymin, Double_t ymax, Option_t *option);
+   void     BuildOptions(Double_t ymin, Double_t ymax, Option_t *option);
+   Double_t Chi2Test(const TH1* h2, Option_t *option = "WW", Double_t *res = nullptr) const override;
    void     Copy(TObject &hnew) const override;
    Bool_t   Divide(TF1 *h1, Double_t c1=1) override;
    Bool_t   Divide(const TH1 *h1) override;

hist/hist/inc/TProfile2D.h

@@ -95,6 +95,7 @@ class TProfile2D : public TH2D {
    static  void      Approximate(Bool_t approx=kTRUE);
    void              BuildOptions(Double_t zmin, Double_t zmax, Option_t *option);
    Int_t     BufferEmpty(Int_t action=0) override;
+   Double_t  Chi2Test(const TH1* h2, Option_t *option = "WW", Double_t *res = nullptr) const override;
    void      Copy(TObject &hnew) const override;
    Bool_t    Divide(TF1 *h1, Double_t c1=1) override;
    Bool_t    Divide(const TH1 *h1) override;

hist/hist/inc/TProfile3D.h

@@ -100,6 +100,7 @@ class TProfile3D : public TH3D {
    static  void      Approximate(Bool_t approx=kTRUE);
    void              BuildOptions(Double_t tmin, Double_t tmax, Option_t *option);
    Int_t     BufferEmpty(Int_t action=0) override;
+   Double_t  Chi2Test(const TH1* h2, Option_t *option = "WW", Double_t *res = nullptr) const override;
    void      Copy(TObject &hnew) const override;
    Bool_t    Divide(TF1 *h1, Double_t c1=1) override;
    Bool_t    Divide(const TH1 *h1) override;

hist/hist/src/TProfile.cxx

@@ -416,6 +416,25 @@ Int_t TProfile::BufferFill(Double_t x, Double_t y, Double_t w)
    return -2;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+/// Run a Chi2Test between two TProfiles.
+/// This calls TH1::Chi2Test() with the option "WW".
+
+Double_t TProfile::Chi2Test(const TH1 *h2, Option_t *option, Double_t *res) const
+{
+   TString opt = option;
+   opt.ToUpper();
+   opt += "WW";
+   opt.ReplaceAll("UU", "");
+   opt.ReplaceAll("UW", "");
+
+   if (auto other = dynamic_cast<const TProfile *>(h2);
+       fErrorMode != kERRORMEAN || (other && other->fErrorMode != kERRORMEAN))
+      Warning("TProfile::Chi2Test", "Chi2 tests only make sense if the error on the mean is used.");
+
+   return TH1::Chi2Test(h2, opt, res);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 /// Copy a Profile histogram to a new profile histogram.
 

hist/hist/src/TProfile2D.cxx

@@ -379,6 +379,25 @@ Int_t TProfile2D::BufferFill(Double_t x, Double_t y, Double_t z, Double_t w)
    return -2;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+/// Run a Chi2Test between two TProfile2D.
+/// This calls TH1::Chi2Test() with the option "WW".
+
+Double_t TProfile2D::Chi2Test(const TH1 *h2, Option_t *option, Double_t *res) const
+{
+   TString opt = option;
+   opt.ToUpper();
+   opt += "WW";
+   opt.ReplaceAll("UU", "WW");
+   opt.ReplaceAll("UW", "WW");
+
+   if (auto other = dynamic_cast<const TProfile2D *>(h2);
+       fErrorMode != kERRORMEAN || (other && other->fErrorMode != kERRORMEAN))
+      Warning("TProfile3D::Chi2Test", "Chi2 tests only make sense if the error on the mean is used.");
+
+   return TH1::Chi2Test(h2, opt, res);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 /// Copy a Profile2D histogram to a new profile2D histogram.
 

hist/hist/src/TProfile3D.cxx

@@ -343,6 +343,25 @@ Int_t TProfile3D::BufferFill(Double_t x, Double_t y, Double_t z, Double_t t, Dou
    return -2;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+/// Run a Chi2Test between two TProfile3D.
+/// This calls TH1::Chi2Test() with the option "WW".
+
+Double_t TProfile3D::Chi2Test(const TH1 *h2, Option_t *option, Double_t *res) const
+{
+   TString opt = option;
+   opt.ToUpper();
+   opt += "WW";
+   opt.ReplaceAll("UU", "WW");
+   opt.ReplaceAll("UW", "WW");
+
+   if (auto other = dynamic_cast<const TProfile3D *>(h2);
+       fErrorMode != kERRORMEAN || (other && other->fErrorMode != kERRORMEAN))
+      Warning("TProfile3D::Chi2Test", "Chi2 tests only make sense if the error on the mean is used.");
+
+   return TH1::Chi2Test(h2, opt, res);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 /// Copy a Profile3D histogram to a new profile2D histogram.