我有一个csv文件，列的值是重复的，并且有它们的数量。
现在我怎样画出这些值的线性图呢？
我试过了，但没用。

import matplotlib.pyplot as plt
import pandas as pd

data = {'location': ['Afghanistan'] * 5 + ['Africa'] * 4, 'new_cases': [3, 0, 0, 3, 6, 0, 1, 0, 0]}
newData = pd.DataFrame(data)

fig, ax = plt.subplots(figsize=(15,7))
byLoc = newData.groupby('location').count()['new_cases'].unstack().plot(ax=ax)

追溯

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
Cell In [141], line 2
      1 fig, ax = plt.subplots(figsize=(15,7))
----> 2 byLoc = newData.groupby('location').count()['new_cases'].unstack().plot(ax=ax)

File ~\anaconda3\envs\py11\Lib\site-packages\pandas\core\series.py:4455, in Series.unstack(self, level, fill_value)
   4412 """
   4413 Unstack, also known as pivot, Series with MultiIndex to produce DataFrame.
   4414 
   (...)
   4451 b    2    4
   4452 """
   4453 from pandas.core.reshape.reshape import unstack
-> 4455 return unstack(self, level, fill_value)

File ~\anaconda3\envs\py11\Lib\site-packages\pandas\core\reshape\reshape.py:483, in unstack(obj, level, fill_value)
    478         return obj.T.stack(dropna=False)
    479 elif not isinstance(obj.index, MultiIndex):
    480     # GH 36113
    481     # Give nicer error messages when unstack a Series whose
    482     # Index is not a MultiIndex.
--> 483     raise ValueError(
    484         f"index must be a MultiIndex to unstack, {type(obj.index)} was passed"
    485     )
    486 else:
    487     if is_1d_only_ea_dtype(obj.dtype):

ValueError: index must be a MultiIndex to unstack, <class 'pandas.core.indexes.base.Index'> was passed