import re
z=str(re.findall(r'drone-dji:FlightRollDegree=\D\+?\-?\d+\.\d+\D',xmp_str))
y=re.findall(r'[+?-?\d+.\d+]',z)
#or if you want to take number without any sighn
#y=re.findall(r'\d+\.\d+',z)
dron_roll=''.join(y)
dron_roll