4장
1 출처: https://scikit-learn.org/stable/tutorial/machine_learning_map/index.html
2 출처 및 참고 API Document: https://scikit-learn.org/stable/modules/generated/sklearn.feature_extraction.text.CountVectorizer.html#sklearn.feature_extraction.text.CountVectorizer.fit_transform()
3 https://ko.wikipedia.org