Effective Preprocessing and Normalization Techniques for COVID-19 Twitter Streams with POS Tagging via Lightweight Hidden Markov Model

Table 6

Preprocessing techniques and method used.

Preprocessing techniques	Methods deployed
Stop–word removal	Rainbow list
Stemming	Snowball stemmer
Emoticon	Regular expression
Tokenization	Unigram, bigram, and -gram
Weighting scheme	TF-IDF