code: def arraydifference(X,Y):
      
      if len(Y) > 0:
          Z = isin(X,Y)
          return X[np.invert(Z)]
      else:
          return X
docs: Elements of a numpy array that do not appear in another.
  
      Fast routine for determining which elements in numpy array `X`
      do not appear in numpy array `Y`.
  
      **Parameters**
  
              **X** :  numpy array
  
                      Numpy array to comapare to numpy array `Y`.
                      Return subset of `X` corresponding to elements not in `Y`.
  
              **Y** :  numpy array
  
                      Numpy array to which numpy array `X` is compared.
                      Return subset of `X` corresponding to elements not in `Y`.
  
      **Returns**
  
              **Z** :  numpy array
  
                      Subset of `X` corresponding to elements not in `Y`.
  
      **See Also:**
  
              :func:`tabular.fast.recarraydifference`, :func:`tabular.fast.isin`