def export(datastore_key, calc_id=-1, exports='csv', export_dir='.'):
    """
    Export an output from the datastore.
    """    
    dstore = util.read(calc_id)
    parent_id = dstore['oqparam'].hazard_calculation_id
    if parent_id:
        dstore.parent = util.read(parent_id)
    dstore.export_dir = export_dir
    with performance.Monitor('export', measuremem=True) as mon:
        for fmt in exports.split(','):
            fnames = export_((datastore_key, fmt), dstore)
            nbytes = sum(os.path.getsize(f) for f in fnames)
            print('Exported %s in %s' % (general.humansize(nbytes), fnames))
    if mon.duration > 1:
        print(mon)
    dstore.close()
Export an output from the datastore.