def get_min_max_values(data, col1, col2):
	"""
    extracts min and max value of two columns

    :param data: ptcf data frame
	:param col1: column 1
	:param col1: column 2
    :return: dict of min and max values of two columns
    """ 
	
	return {
		'ds1_min' : data[col1].min(),
		'ds1_max' : data[col1].max(),
		'ds2_min' : data[col2].min(),
		'ds2_max' : data[col2].max()
	}