def extract_action_list_from_path(path_list):
    """
    Converts a block idx path to action list.

    Args
        path_list:  <list>  list of block idx from source block to dest block.

    Returns
        action_list: <list> list of string discrete action commands (e.g. ['movesouth 1', 'movewest 1', ...]
    """
    action_trans = {-21: 'movenorth 1', 21: 'movesouth 1', -1: 'movewest 1', 1: 'moveeast 1'}
    alist = []
    for i in range(len(path_list) - 1):
        curr_block, next_block = path_list[i:(i + 2)]
        alist.append(action_trans[next_block - curr_block])

    return alist