title: Understanding min_df and max_df in scikit CountVectorizer
body: <p>I have five text files that I input to a CountVectorizer. When specifying <code>min_df</code> and <code>max_df</code> to the CountVectorizer instance what does the min/max document frequency exactly mean? Is it the frequency of a word in its particular text file or is it the frequency of the word in the entire overall corpus (five text files)?</p>
  <p>What are the differences when <code>min_df</code> and <code>max_df</code> are provided as integers or as floats?</p>
  <p><a href="https://scikit-learn.org/stable/modules/generated/sklearn.feature_extraction.text.CountVectorizer.html#sklearn-feature-extraction-text-countvectorizer" rel="noreferrer">The documentation</a> doesn't seem to provide a thorough explanation nor does it supply an example to demonstrate the use of these two parameters. Could someone provide an explanation or example demonstrating <code>min_df</code> and <code>max_df</code>?</p>