Logo ROOT   6.21/01
Reference Guide
FITS_tutorial5.C
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1 /// \file
2 /// \ingroup tutorial_FITS
3 /// \notebook
4 ///
5 /// Open a FITS file whose primary array represents
6 /// a spectrum (flux vs wavelength)
7 ///
8 /// \macro_code
9 /// \macro_output
10 ///
11 /// \author Claudi Martinez
12 
13 using Upvd_t = std::unique_ptr<TVectorD>;
14 
15 void FITS_tutorial5()
16 {
17  // We open a FITS file that contains a table with 9 rows and 8 columns. Column 4 has name
18  // 'mag' and contains a vector of 6 numeric components. The values of vectors in rows 1 and 2 (column 4) are:
19  // Row1: (99.0, 24.768, 23.215, 21.68, 21.076, 20.857)
20  // Row2: (99.0, 21.689, 20.206, 18.86, 18.32 , 18.128 )
21  // WARNING: when coding, row and column indices start from 0
22 
23  TString dir = gROOT->GetTutorialDir();
24 
25  // Open the table
26  TFITSHDU hdu(dir + "/fitsio/sample4.fits[1]");
27 
28  // Read vectors at rows 1 and 2 (indices 0 and 1)
29  std::array<Upvd_t, 2> vs{Upvd_t(hdu.GetTabRealVectorCell(0, "mag")), Upvd_t(hdu.GetTabRealVectorCell(1, "mag"))};
30  for (auto &&v : vs) {
31  for(auto i : ROOT::TSeqI(v->GetNoElements())) {
32  if (i > 0)
33  printf(", ");
34  printf("%lg", (*v)[i]); // NOTE: the asterisk is for using the overloaded [] operator of the TVectorD object
35  }
36  printf(")\n");
37  }
38 
39  // We now dump all rows using the function GetTabRealVectorCells()
40  std::unique_ptr<TObjArray> vectorCollection(hdu.GetTabRealVectorCells("mag"));
41  for (auto vObj : *vectorCollection) {
42  auto &v = *static_cast<TVectorD*>(vObj);
43  for (auto i : ROOT::TSeqI(v.GetNoElements())) {
44  if (i > 0) printf(", ");
45  printf("%lg", (v[i]));
46  }
47  printf(")\n");
48  }
49 }
TVectorT.
Definition: TMatrixTBase.h:79
#define gROOT
Definition: TROOT.h:415
Basic string class.
Definition: TString.h:131
FITS file interface class.
Definition: TFITS.h:34
A pseudo container class which is a generator of indices.
Definition: TSeq.hxx:66