def __init__(self, data=None, unit='au'):
if data is None:
self.data = None
else:
self.data = np.array(data)
self.unit = unit
self.mean, self.std, self.num = statistics(self.data)
def append(self, value):
'Add value to array and update statistics'
if self.data is None:
self.data = np.array([value])
else:
assert isinstance(self.data, np.ndarray)
self.data = np.append(self.data, value)
self.mean, self.std, self.num = statistics(self.data)
