txt=str('size="0.2 0.2 0.1"');
new_val="1 1 1"
replacement='size="'+str(new_val)+'"';
file = open("/home/dylan/Téléchargements/box_small_incline.urdf",'r').read();
str = file.replace(txt,replacement);
f = open("/home/dylan/nouveau_fichier.urdf","w+")
f.write(str)
f.close()