// Open a FITS file whose primary array represents
// a spectrum (flux vs wavelength)
void FITS_tutorial4()
{
printf("\n\n--------------------------------\n");
printf("WELCOME TO FITS tutorial #4 !!!!\n");
printf("--------------------------------\n");
printf("We're gonna open a FITS file that contains the\n");
printf("primary HDU and a little data table.\n");
printf("The data table is extension #1 and it has 2 rows.\n");
printf("We want to read only the rows that have the column\n");
printf("named DATAMAX greater than 2e-15 (there's only 1\n");
printf("matching row)\n");
printf("Data copyright: NASA\n\n");
if (!gROOT->IsBatch()) {
//printf("Press ENTER to start..."); getchar();
}
TString dir = gSystem->DirName(gInterpreter->GetCurrentMacroName());
//Open the table extension number 1)
TFITSHDU *hdu = new TFITSHDU(dir+"/sample2.fits[1][DATAMAX > 2e-15]");
if (hdu == 0) {
printf("ERROR: could not access the HDU\n"); return;
}
//printf("Press ENTER to see information about the table's columns..."); getchar();
hdu->Print("T");
printf("\n\n........................................\n");
printf("Press ENTER to see full table contents (maybe you should resize\n");
//printf("this window as large as possible before)..."); getchar();
hdu->Print("T+");
printf("\n\n........................................\n");
//printf("Press ENTER to get only the DATAMAX value of the matched row..."); getchar();
TVectorD *v = hdu->GetTabRealVectorColumn("DATAMAX");
printf("%lg\n", (*v)[0]);
printf("Does the matched row have DATAMAX > 2e-15? :-)\n");
//Clean up
delete v;
delete hdu;
}
// Open a FITS file whose primary array represents
// a spectrum (flux vs wavelength)
void FITS_tutorial2()
{
printf("\n\n--------------------------------\n");
printf("WELCOME TO FITS tutorial #2 !!!!\n");
printf("--------------------------------\n");
printf("We're gonna open a FITS file that contains the\n");
printf("primary HDU and a little data table.\n");
printf("The primary HDU is an array of 2 rows by 2040 columns, and\n");
printf("they represent a radiation spectrum. The first row contains\n");
printf("the flux data, whereas the second row the wavelengths.\n");
printf("Data copyright: NASA\n\n");
if (!gROOT->IsBatch()) {
//printf("Press ENTER to start..."); getchar();
}
TString dir = gSystem->DirName(__FILE__);
// Open primary HDU from file
TFITSHDU *hdu = new TFITSHDU(dir+"/sample2.fits");
if (hdu == 0) {
printf("ERROR: could not access the HDU\n"); return;
}
printf("File successfully open!\n");
// Dump the HDUs within the FITS file
// and also their metadata
//printf("Press ENTER to see summary of all data stored in the file:"); getchar();
hdu->Print("F+");
printf("....................................\n");
printf("We are going to generate a TGraph from vectors\n");
//printf("within the primary array. Press ENTER to continue.."); getchar();
TVectorD *Y = hdu->GetArrayRow(0);
TVectorD *X = hdu->GetArrayRow(1);
TGraph *gr = new TGraph(*X,*Y);
// Show the graphic
TCanvas *c = new TCanvas("c1", "FITS tutorial #2", 800, 800);
gr->Draw("BA");
// Clean up
delete X;
delete Y;
delete hdu;
}
// Open a FITS file and retrieve the first plane of the image array
// as a TASImage object
void FITS_tutorial1()
{
printf("\n\n--------------------------------\n");
printf("WELCOME TO FITS tutorial #1 !!!!\n");
printf("--------------------------------\n");
printf("We're gonna open a FITS file that contains only the\n");
printf("primary HDU, consisting on an image.\n");
printf("The object you will see is a snapshot of the NGC7662 nebula,\n");
printf("which was taken by the author on November 2009 in Barcelona (CATALONIA).\n\n");
if (!gROOT->IsBatch()) {
//printf("Press ENTER to start..."); getchar();
}
// Open primary HDU from file
TFITSHDU *hdu = new TFITSHDU("sample1.fits");
if (hdu == 0) {
printf("ERROR: could not access the HDU\n"); return;
}
printf("File successfully open!\n");
// Dump the HDUs within the FITS file
// and also their metadata
//printf("Press ENTER to see summary of all data stored in the file:"); getchar();
hdu->Print("F+");
printf("....................................\n");
// Here we get the exposure time.
//printf("Press ENTER to retrieve the exposure time from the HDU metadata..."); getchar();
printf("Exposure time = %s\n", hdu->GetKeywordValue("EXPTIME").Data());
// Read the primary array as a matrix,
// selecting only layer 0.
// This function may be useful to
// do image processing.
printf("....................................\n");
printf("We can read the image as a matrix of values.\n");
printf("This feature is useful to do image processing, e.g:\n");
printf("histogram equalization, custom filtering, ...\n");
//printf("Press ENTER to continue..."); getchar();
TMatrixD *mat = hdu->ReadAsMatrix(0);
mat->Print();
delete mat;
// Read the primary array as an image,
// selecting only layer 0.
printf("....................................\n");
printf("Now the primary array will be read both as an image and as a histogram,\n");
printf("and they will be shown in a canvas.\n");
//printf("Press ENTER to continue..."); getchar();
TASImage *im = hdu->ReadAsImage(0);
// Read the primary array as a histogram.
// Depending on array dimensions, returned
// histogram will be 1D, 2D or 3D
TH1 *hist = hdu->ReadAsHistogram();
TCanvas *c = new TCanvas("c1", "FITS tutorial #1", 800, 300);
c->Divide(2,1);
c->cd(1);
im->Draw();
c->cd(2);
hist->Draw("COL");
// Clean up
delete hdu;
}