def create_session_string(prefix, fmat, orb, rootsift, ratio, session):
	"""Create an identifier string from the most common parameter options.

	Keyword arguments:
	prefix -- custom string appended at the beginning of the session string
	fmat -- bool indicating whether fundamental matrices or essential matrices are estimated
	orb -- bool indicating whether ORB features or SIFT features are used
	rootsift -- bool indicating whether RootSIFT normalization is used
	ratio -- threshold for Lowe's ratio filter
	session -- custom string appended at the end of the session string
	"""
	session_string = prefix + '_'
	if fmat:
		session_string += 'F_'
	else:
		session_string += 'E_'
	
	if orb:	session_string += 'orb_'
	if rootsift: session_string += 'rs_'
	session_string += 'r%.2f_' % ratio
	session_string += session

	return session_string