new file: scratch/make_pretty.C make pretty plots for the thesis

scratch/make_pretty.C

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+// =============================================================================
+// make_pretty.C
+//
+// Feed it a ROOT file and a histogram name, get a publication-quality PNG.
+//
+// Usage:
+//   root -l -b -q 'make_pretty.C("myfile.root", "histName")'
+//   root -l -b -q 'make_pretty.C("myfile.root", "histName", "x label", "y label")'
+//
+// Supports TH1F, TH1D, TH2F, TH2D — type is detected automatically.
+// Output PNG is written to the same directory as the input file.
+// =============================================================================
+
+#include "TFile.h"
+#include "TH1.h"
+#include "TH2.h"
+#include "TCanvas.h"
+#include "TStyle.h"
+#include "TGaxis.h"
+#include "TLatex.h"
+#include "TSystem.h"
+#include "TROOT.h"
+
+#include <iostream>
+#include <string>
+
+// ---------------------------------------------------------------------------
+// Style — called once before anything is drawn
+// ---------------------------------------------------------------------------
+void SetStyle() {
+    gROOT->SetStyle("Plain");
+    gStyle->SetOptStat(0);
+    gStyle->SetOptTitle(0);
+
+    gStyle->SetTextFont(42);
+    gStyle->SetLabelFont(42, "xyz");
+    gStyle->SetTitleFont(42, "xyz");
+
+    gStyle->SetLabelSize(0.045, "xyz");
+    gStyle->SetTitleSize(0.050, "xyz");
+    gStyle->SetTitleOffset(1.15, "x");
+    gStyle->SetTitleOffset(1.20, "y");
+
+    gStyle->SetTickLength(0.025, "xy");
+    gStyle->SetNdivisions(510, "xy");
+    TGaxis::SetMaxDigits(4);
+
+    gStyle->SetCanvasColor(0);
+    gStyle->SetPadColor(0);
+    gStyle->SetFrameLineWidth(2);
+    gStyle->SetHistLineWidth(2);
+
+    gStyle->SetPadLeftMargin(0.14);
+    gStyle->SetPadRightMargin(0.04);
+    gStyle->SetPadBottomMargin(0.13);
+    gStyle->SetPadTopMargin(0.06);
+    gStyle->SetPadTickX(1);
+    gStyle->SetPadTickY(1);
+
+    // kBird: perceptually uniform, grayscale-safe, colorblind-friendly
+    gStyle->SetPalette(kBird);
+    gStyle->SetNumberContours(255);
+}
+
+// ---------------------------------------------------------------------------
+// make_pretty()
+// ---------------------------------------------------------------------------
+void make_pretty(const char* rootFile,
+                 const char* histName,
+                 const char* xlabel = "",
+                 const char* ylabel = "") {
+
+    SetStyle();
+
+    // --- Open file ----------------------------------------------------------
+    TFile* f = TFile::Open(rootFile, "READ");
+    if (!f || f->IsZombie()) {
+        std::cerr << "ERROR: Cannot open " << rootFile << "\n";
+        return;
+    }
+
+    TObject* obj = f->Get(histName);
+    if (!obj) {
+        std::cerr << "ERROR: '" << histName << "' not found in " << rootFile << "\n";
+        f->Close();
+        return;
+    }
+
+    // --- Clone and detach BEFORE closing the file ---------------------------
+    // ROOT ties every histogram to the TDirectory of the file it came from.
+    // When f->Close() is called, ROOT deletes all objects in that directory —
+    // including the clone — unless SetDirectory(0) is called first to detach
+    // it. Drawing a deleted object causes the segfault you are seeing.
+    TObject* clone = obj->Clone(Form("%s_clone", histName));
+    if (!clone) {
+        std::cerr << "ERROR: Clone failed for '" << histName << "'\n";
+        f->Close();
+        return;
+    }
+    if (clone->InheritsFrom(TH1::Class()))
+        ((TH1*)clone)->SetDirectory(0);   // detach — survives file close
+    f->Close();
+
+    // --- Detect dimension ---------------------------------------------------
+    bool is2D = clone->InheritsFrom(TH2::Class());
+
+    // --- Canvas: 2100 px wide = 7 in at 300 DPI -----------------------------
+    int canvasW = 2100;
+    int canvasH = is2D ? 1800 : 1575;   // square-ish for 2D, 4:3 for 1D
+
+    TCanvas c("c", "", 0, 0, canvasW, canvasH);
+    c.cd();
+
+    // Widen right margin for the colz palette bar
+    if (is2D) gPad->SetRightMargin(0.13);
+
+    // --- Draw ---------------------------------------------------------------
+    if (is2D) {
+        TH2* h = (TH2*)clone;
+        h->SetStats(0);
+        h->GetXaxis()->SetTitle("");
+        h->GetYaxis()->SetTitle("");
+        h->Draw("colz");
+    } else {
+        TH1* h = (TH1*)clone;
+        h->SetStats(0);
+        h->SetLineColor(kBlue+1);
+        h->SetFillColorAlpha(kBlue+1, 0.25);
+        h->SetFillStyle(1001);
+        h->GetXaxis()->SetTitle("");
+        h->GetYaxis()->SetTitle("");
+        h->Draw("hist");
+    }
+
+    // --- Axis labels via TLatex (full typographic control) ------------------
+    TLatex tex;
+    tex.SetNDC();
+    tex.SetTextFont(42);
+    tex.SetTextSize(0.050);
+
+    // X: y=0.06 sits just below the tick numbers inside the bottom margin (0.13).
+    // Y: x=0.08 sits just left of the tick numbers inside the left margin (0.14).
+    // Increase either value to push the label further from the axis.
+    if (strlen(xlabel) > 0)
+        tex.DrawLatex(0.46, 0.05, xlabel);
+
+    if (strlen(ylabel) > 0) {
+        tex.SetTextAngle(90);
+        tex.DrawLatex(0.08, 0.40, ylabel);
+        tex.SetTextAngle(0);
+    }
+
+    // --- Save ---------------------------------------------------------------
+    // Build output path: same directory as input file, named after the histogram
+    std::string inPath(rootFile);
+    std::string dir = inPath.substr(0, inPath.find_last_of("/\\"));
+    if (dir == inPath) dir = ".";   // no directory component — use cwd
+
+    std::string outPath = dir + "/" + std::string(histName) + ".png";
+    // Replace any "/" inside histName (e.g. "folder/hist") with "_"
+    for (char& ch : outPath)
+        if (ch == '/') ch = '_';
+
+    c.Modified();
+    c.Update();
+    c.SaveAs(outPath.c_str());
+
+    std::cout << "Saved: " << outPath << "\n";
+}