code: def _get_corpus_characteristic_scores(self, json_df):
      bg_terms = (
          self.term_doc_matrix.get_scaled_f_scores_vs_background()
      )
      bg_terms = bg_terms["Scaled f-score"]
      bg_terms.name = "bg"
      bg_terms = bg_terms.reset_index()
      bg_terms.columns = [
          "term" if x in ["index", "word"] else x
          for x in bg_terms.columns
      ]
      json_df = pd.merge(json_df, bg_terms, on="term", how="left")
      return json_df.loc[:, "bg"].fillna(0)
  
imports: import logging
  import sys
  import numpy
  import pandas
  from scipy.stats import rankdata
  from scattertext.PValGetter import get_p_vals
  from scattertext.Scalers import percentile_min, percentile_alphabetical
  from scattertext.ScatterChartData import ScatterChartData
  from scattertext.TermDocMatrixFilter import filter_bigrams_by_pmis, filter_out_unigrams_that_only_occur_in_one_bigram
  from scattertext.termscoring import ScaledFScore
  from scattertext.termscoring.RankDifference import RankDifference
  from scattertext.termscoring.CornerScore import CornerScore
label_desc: Use image node_id 13 for calling the ScatterChart obj's underlying member method code with example usage: obj._get_corpus_characteristic_scores(json_df) and returns: json_df