... , (S et al., 2017), (Guo et al., 2019), (Dilawari and Khan, 2019), Unsupervised learning (Song et al., 2011), (Yousefi-azar and Hamey, 2017), (Tayal et al., 2016), (Alami et al., 2019), (Y. , , (Sun and Zhuge, 2018), (Zhou et al., 2016) Single document (Li et al., 2016), (Patel et al., 2019), (Sharifi et al., 2013), (Goyal et al., 2013), , (Cagliero et al., 2019) Multidocument (Malallah and Ali, 2017), (Patel et al., 2019), (Lee et al., 2013), (Padmapriya and Duraiswamy, 2014), (Fuad et al., 2019), (Khan et al., 2015a), (Khan et al., 2015b), (S et al., 2017), (Sanchez-gomez et al., 2018), , (Qiang et al., 2016), (Ansamma et al., 2017), (Widjanarko et al., 2018), (Azhari et al., 2018), (Sharifi et al., 2013), (Alzuhair and Al-dhelaan, 2019), (Liu et al., 2012), (Bian et al., 2013), (Yulianti et al., 2017), (Qiang et al., 2019), (Ketui et al., 2015), (Yan and Wan, 2015), (Baralis et al., 2015) Optimization (Song et al., 2011), (Abbasi-ghalehtaki et al., 2016), (Binwahlan et al., 2009a), (Khosravi et al., 2008), (Sanchez-gomez et al., 2018) Real-time (Maio et al., 2015), (Rodríguez-Vidal et al., 2019), (Chua and Asur, 2009), (Kacprzyk et al., 2008), (Kacprzyk et al., 2008), (Fu et al., 2015), (Chellal et al., 2016), Preprocessing is the initial process for preparing data. Unstructured data is changed to be structured data according to the needs for summation. ...