def load_to_array(self, keys):
        """
        This loads the data contained in the catalogue into a numpy array. The
        method works only for float data

        :param keys:
            A list of keys to be uploaded into the array
        :type list:
        """
        # Preallocate the numpy array
        data = np.empty((len(self.data[keys[0]]), len(keys)))
        for i in range(0, len(self.data[keys[0]])):
            for j, key in enumerate(keys):
                data[i, j] = self.data[key][i]
        return data
def load_to_array ( self , keys ) : data = np . empty ( ( len ( self . data [ keys [ 0 ] ] ) , len ( keys ) ) ) for i in range ( 0 , len ( self . data [ keys [ 0 ] ] ) ) : for j , key in enumerate ( keys ) : data [ i , j ] = self . data [ key ] [ i ] return data
This loads the data contained in the catalogue into a numpy array. The
        method works only for float data

        :param keys:
            A list of keys to be uploaded into the array
        :type list: