Quick and partial glance of the data matrix.

        Parameters
        ----------
        nitems : int
            Number of items to glance from the dataset.
            Default : 5

        Returns
        -------
        dict

def glance(self, nitems=5):
        """Quick and partial glance of the data matrix.

        Parameters
        ----------
        nitems : int
            Number of items to glance from the dataset.
            Default : 5

        Returns
        -------
        dict

        """
        nitems = max([1, min([nitems, self.num_samples - 1])])
        return self.__take(nitems, iter(self.__data.items()))