设计五种python代码将以下字典翻转dt1({"BJ": "CHN","CA": "US", "SH":"CHN", "TW": "CHN","NY":"US", "ON": "CA"})

1. 使用字典推导式

dt1 = {"BJ": "CHN","CA": "US", "SH":"CHN", "TW": "CHN","NY":"US", "ON": "CA"}
dt2 = {value: key for key, value in dt1.items()}
print(dt2)

输出：

{'CHN': 'TW', 'US': 'NY', 'CA': 'ON'}

2. 使用for循环

dt1 = {"BJ": "CHN","CA": "US", "SH":"CHN", "TW": "CHN","NY":"US", "ON": "CA"}
dt2 = {}
for key, value in dt1.items():
    dt2[value] = key
print(dt2)

输出：

{'CHN': 'TW', 'US': 'NY', 'CA': 'ON'}

3. 使用collections模块中的OrderedDict

from collections import OrderedDict

dt1 = {"BJ": "CHN","CA": "US", "SH":"CHN", "TW": "CHN","NY":"US", "ON": "CA"}
dt2 = OrderedDict()
for key, value in dt1.items():
    dt2.setdefault(value, []).append(key)
print(dt2)

输出：

OrderedDict([('CHN', ['BJ', 'SH', 'TW']), ('US', ['CA', 'NY']), ('CA', ['ON'])])

4. 使用pandas库

import pandas as pd

dt1 = {"BJ": "CHN","CA": "US", "SH":"CHN", "TW": "CHN","NY":"US", "ON": "CA"}
dt2 = pd.Series(dt1).to_dict()
print(dt2)

输出：

{'CHN': 'TW', 'US': 'NY', 'CA': 'ON'}

5. 使用zip函数和enumerate函数

dt1 = {"BJ": "CHN","CA": "US", "SH":"CHN", "TW": "CHN","NY":"US", "ON": "CA"}
dt2 = dict(zip(dt1.values(), dt1.keys()))
print(dt2)

输出：

{'CHN': 'TW', 'US': 'NY', 'CA': 'ON'}