def arraydifference(X,Y):
if len(Y) > <NUM_LIT:0>:<EOL><INDENT>Z = isin(X,Y)<EOL>return X[np.invert(Z)]<EOL><DEDENT>else:<EOL><INDENT>return X<EOL><DEDENT>
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`