Asymmetric Unit

def __init__(self, elements, positions, labels=None, **kwargs):
    """
    Create an asymmetric unit object from a list of Elements and 
    an array of fractional coordinates.


    Arguments:
        elements (List[Element]): N length list of elements associated with the sites
        positions (array_like): (N, 3) array of site positions in fractional coordinates
        labels (array_like, optional): labels (array_like): N length array of string labels for each site
        **kwargs: Additional properties (will populate the properties member)
            to store in this asymmetric unit

    """
    self.elements = elements
    self.atomic_numbers = np.asarray([x.atomic_number for x in elements])
    self.positions = np.asarray(positions)
    self.properties = {}
    self.properties.update(kwargs)
    if labels is None:
        self.labels = []
        label_index = defaultdict(int)
        for el in self.elements:
            label_index[el] += 1
            self.labels.append("{}{}".format(el, label_index[el]))
    else:
        self.labels = labels
    self.labels = np.array(self.labels)

@classmethod
def from_records(cls, records):
    """Initialize an AsymmetricUnit from a list of dictionary like objects

    Arguments:
        records (iterable): An iterable containing dict_like objects with `label`,
            `element`, `position` and optionally `occupation` stored.
    """
    labels = []
    elements = []
    positions = []
    occupation = []
    for r in records:
        labels.append(r["label"])
        elements.append(Element[r["element"]])
        positions.append(r["position"])
        occupation.append(r.get("occupation", 1.0))
    positions = np.asarray(positions)
    return AsymmetricUnit(elements, positions, labels=labels, occupation=occupation)