code: def _standardize(self, X):
      if self.means is None or self.stds is None:
          raise RuntimeError("Fit model first")
  
      return (X - self.means) / self.stds
  
file_path: hypertools/hypertools/_externals/ppca.py
imports: import os
  import numpy
  from scipy.linalg import orth
label_desc: Use image node_id 2 for calling the PPCA obj's underlying member method code with example usage: obj._standardize(X) and returns: unknown