def METHOD_NAME(node):
    particleset = node.find("particleset[@name='ion0']")
    npos = int(particleset.attrib['size'])
    pos_node = particleset.find("attrib[@name='position']")
    pos_values = [float(a) for a in pos_node.text.split()]
    pos = np.array(pos_values).reshape( (npos, 3) )
    elements_node = particleset.find("attrib[@name='ionid']")
    elements = elements_node.text.split()
    return pos, elements