I have installed devtools.
But the problem is with package ggiraphExtra.
I installed it. But when i ticked it in package there was this message :
Erreur : package or namespace load failed for ‘ggiraphExtra’ in dyn.load(file, DLLpath = DLLpath, ...):
impossible de charger l'objet partagé '/Library/Frameworks/R.framework/Versions/3.6/Resources/library/systemfonts/libs/systemfonts.so':
dlopen(/Library/Frameworks/R.framework/Versions/3.6/Resources/library/systemfonts/libs/systemfonts.so, 6): Library not loaded: /opt/X11/lib/libfreetype.6.dylib
Referenced from: /Library/Frameworks/R.framework/Versions/3.6/Resources/library/systemfonts/libs/systemfonts.so
Reason: image not found