code: def filter_bigrams_by_pmis(
      word_freq_df, threshold_coef=DEFAULT_PMI_THRESHOLD_COEFFICIENT
  ):
      # type: (pd.DataFrame, int) -> pd.DataFrame
      if len(word_freq_df.index) == 0:
          return word_freq_df
      low_pmi_bigrams = get_low_pmi_bigrams(
          threshold_coef, word_freq_df
      )
      return word_freq_df.drop(low_pmi_bigrams.index)
  
file_path: scattertext/scattertext/TermDocMatrixFilter.py
imports: from collections import Counter
  import numpy
  from scattertext.Common import DEFAULT_PMI_THRESHOLD_COEFFICIENT
label_desc: Use image node_id 1 for calling a global function with example usage: filter_bigrams_by_pmis(word_freq_df, threshold_coef) and returns: word_freq_df, word_freq_df