code: def extract(self):
          
          return np.vstack([self[r] for r in self.dtype.names]).T.squeeze()
docs: Creates a copy of this tabarray in the form of a numpy ndarray.
  
          Useful if you want to do math on array elements, e.g. if you have a 
          subset of the columns that are all numerical, you can construct a 
          numerical matrix and do matrix operations.