code: def log_normalize(data):
      
      if sp.issparse(data):
          data = data.copy()
          data.data = np.log2(data.data + 1)
          return data
  
      return np.log2(data.astype(np.float64) + 1)
docs: Perform log transform log(x + 1).
      
      Parameters
      ----------
      data : array_like