How to convert sky map projections?

The following code illustrates how to convert a map in HealPix projection into a map in cartesian projection. Map conversion is performed using the += operator that adds the bilinearly interpolated intensity values from one map to another. The example code applies to any kind of map projections.

C++

GSkyMap healpix("healpix.fits");
GSkyMap map("CAR","GAL",0.0,0.0,0.5,0.5,100,100);
map += healpix;
map.save("carmap.fits");

Python

healpix = gammalib.GSkyMap('healpix.fits')
map = gammalib.GSkyMap('CAR','GAL',0.0,0.0,0.5,0.5,100,100)
map += healpix
map.save('carmap.fits')