绘图时新数据框的Keyerror

Question

Keyerror：创建新数据帧然后尝试绘制新数据帧后出现 0。

最初，代码有助于绘制原始数据帧。删除了少量行（~5 行）并创建了一个新的数据框。新数据框显示没有问题，但是在尝试绘制新数据框时显示 Keyerror：0。我试图解决这个问题但没有成功。

以下是替换、删除缺失数据和创建新数据框的脚本。

df_pre_orderset2_t = df_pre_orderset2.replace(0, np.nan)
df_pre_orderset2_top = df_pre_orderset2_t.dropna()
pd.set_option('display.max_colwidth', None)

df_pre_orderset2_to_10 = df_pre_orderset2_top.head(10)
df_pre_orderset2_top10 = pd.DataFrame(df_pre_orderset2_to_10)
df_pre_orderset2_top10

配剧情脚本如下

plt.figure(figsize=(9,7))
ax = plt.gca()
x = df_pre_orderset2_top10['warning_status']
y = df_pre_orderset2_top10['count']
n = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j']
t = np.arange(10)

plt.title('Warning distribution versus order sets')
plt.ylabel('Warning count by order sets')
plt.xlabel('Warning alerts')
plt.scatter(x, y, c=t, s=100, alpha=1.0, marker='^')
plt.gcf().set_size_inches(13,8)

#scatter labels
for i, txt in enumerate(n):
   ax.annotate(txt, (x[i],y[i]))

plt.show()

此 returns 拟议情节的完整轮廓和关键错误：0，如下所示。

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
~/opt/anaconda3/lib/python3.8/site-packages/pandas/core/indexes/base.py in get_loc(self, key, method, tolerance)
   3079             try:
-> 3080                 return self._engine.get_loc(casted_key)
   3081             except KeyError as err:

pandas/_libs/index.pyx in pandas._libs.index.IndexEngine.get_loc()

pandas/_libs/index.pyx in pandas._libs.index.IndexEngine.get_loc()

pandas/_libs/hashtable_class_helper.pxi in pandas._libs.hashtable.Int64HashTable.get_item()

pandas/_libs/hashtable_class_helper.pxi in pandas._libs.hashtable.Int64HashTable.get_item()

KeyError: 0

The above exception was the direct cause of the following exception:

KeyError                                  Traceback (most recent call last)
<ipython-input-161-0cc4009cf4a7> in <module>
     16 #scatter labels
     17 for i, txt in enumerate(n):
---> 18     ax.annotate(txt, (x[i],y[i]))
     19 
     20 plt.show()

~/opt/anaconda3/lib/python3.8/site-packages/pandas/core/series.py in __getitem__(self, key)
    851 
    852         elif key_is_scalar:
--> 853             return self._get_value(key)
    854 
    855         if is_hashable(key):

~/opt/anaconda3/lib/python3.8/site-packages/pandas/core/series.py in _get_value(self, label, takeable)
    959 
    960         # Similar to Index.get_value, but we do not fall back to positional
--> 961         loc = self.index.get_loc(label)
    962         return self.index._get_values_for_loc(self, loc, label)
    963 

~/opt/anaconda3/lib/python3.8/site-packages/pandas/core/indexes/base.py in get_loc(self, key, method, tolerance)
   3080                 return self._engine.get_loc(casted_key)
   3081             except KeyError as err:
-> 3082                 raise KeyError(key) from err
   3083 
   3084         if tolerance is not None:

KeyError: 0

Answer 1

失败的行是 ax.annotate(txt, (x[i],y[i]))，并且在 i=0 时失败。 x 和 y 都是 Series 对象，它们是从 df_pre_orderset2_top10 中获取的列，所以我猜测当您从该数据框中删除行时，索引为 0 的行已被删除。您应该能够通过显示数据框来验证这一点。

如果是这种情况，您可以在提取 x 和 y 列之前 reset the index 到该数据框。设置 drop=True 以确保旧索引不会作为新列添加到数据框中。

df_pre_orderset2_top10.reset_index(drop=True, inplace=True)

这应该可以解决问题。

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