Python 字典 键值和字典值互换 key和value互换

'''
已有word_index，格式如下
{'word1': 1,
 'word2': 2,
 'word3': 3,
 ...
}
'''
# 快速互换
index_word_map = {v:k for k,v in word_index.items()}
'''
{1:'word1',
 2:'word2',
 3:'word3',
 ...
}
'''