In recent years, big data has rapidly developed into a hotspot that attracts great attention from academia, industry, and even governments around the world [1–3]. Nature and Science have
published special issues dedicated to discuss the opportunities and challenges brought by big data [4,5]. McKinsey, the well-known management and consulting firm, alleged that big data has penetrated into every area of today’s industry and business functions and has become an important factor in production [6].