docstr: Method to initialize the model. Create and read a similarity matrix
docstr_tok: ["Method","to","initialize","the","model",".","Create","and","read","a","similarity","matrix"]
code: def init_model(self):
      """
      Method to initialize the model. Create and read a similarity matrix
  
      """
      if self.similarity_file is not None:
          similarity = ReadFile(
              self.similarity_file,
              sep=self.similarity_sep,
              as_binary=False,
          ).read_metadata_or_similarity()
  
          self.si_matrix = np.zeros((len(self.items), len(self.items)))
  
          # Fill similarity matrix
          for i in similarity["col_1"]:
              for i_j in similarity["dict"][i]:
                  self.si_matrix[
                      self.item_to_item_id[i],
                      self.item_to_item_id[int(i_j)],
                  ] = similarity["dict"][i][i_j]
  
          # Remove NaNs
          self.si_matrix[np.isnan(self.si_matrix)] = 0.0
  
      else:
          raise ValueError(
              "This algorithm needs a similarity matrix file!"
          )
  
file_path: CaseRecommender/caserec/recommenders/item_recommendation/content_based.py
imports: import numpy
  from caserec.recommenders.item_recommendation.base_item_recommendation import BaseItemRecommendation
  from caserec.utils.process_data import ReadFile
  from caserec.utils.extra_functions import timed
label_desc: Use image node_id 2 for calling the ContentBased obj's underlying member method code with example usage: obj.init_model() without return types