def parse_site_distribution( site_distribution ):
    """
    Converts a site distribution using species labels into one using integer labels.

    Args:
        site_distribution (dict): e.g. `{ 'Mg': 1, 'Li': 3 }`

    Returns:
        numeric_site_distribution ( dict): e.g. `{ 1:1, 0:3 }`
        numeric_site_mapping (dict): e.g. `{ 0:'Mg', 1:'Li' }`
    """
    numeric_site_distribution = {}
    numeric_site_mapping = {}
    for i,k in enumerate( site_distribution.keys() ):
        numeric_site_distribution[i] = site_distribution[k]
        numeric_site_mapping[i] = k
    return numeric_site_distribution, numeric_site_mapping