如何解决这个图形尺寸错误的plot问题？

Question

当我在进行绘图测试时，每次绘制数据档案中的图形都会遇到相同的错误。我的一位同事在她的电脑上运行了相同的程序，而且运行正常，因此我不确定是否需要导入额外的库或进行更新。以下是导致错误的那行代码：

def sub_plot_weekday(df):

    fechas = []

    for i in range(len(df.index)):
        date = str(df.index[i])[0:7]
        if date not in fechas:
            fechas.append(date)
    #print(fechas)

    n_subplots = len(fechas)
    n_col = 2
    n_rows = math.ceil(n_subplots/n_col)

    fig = plt.figure(figsize = (20, 12))

    for d in range(len(fechas)):
        #Guardamos en una var el df filtrado x fecha
        filter_df = df[fechas[d]].copy()
        #Guardamos en una lista el nombre de cada día para cada "Fecha" y la ponemos en una columna
        #print(filter_df)
        dates = filter_df.index
        name_m = dates[0].strftime("%B")
        list_weekdays = [dates[i].date().strftime("%A") for i in range(len(dates))]
        filter_df['weekday'] = list_weekdays
        # Creamos un df agrupando por día de semana contando eventos
        grouped_by_weekday = pd.DataFrame(filter_df[['EVENT', 'weekday']][filter_df['EVENT'] != 0].groupby('weekday').count())

        days_index = grouped_by_weekday.index.tolist()
        days_values = grouped_by_weekday.EVENT.tolist()

        order_day, order_val = reorder_lists(days_index, days_values)
        #Añadimos subplot
        plt.subplot(n_rows, n_col, d+1)
        plt.title('Number of Operations per Weekday (' + name_m + ' ' +fechas[d][:4] + ')',fontsize= 17)
        plt.bar(order_day, order_val, color = 'purple') #(0.5,0.1,0.5,0.6)
        #plt.xticks(order_day, rotation=45)
        for i, val in enumerate(order_val):
            plt.text(i, val, int(val), horizontalalignment='center', verticalalignment='bottom', fontdict={'fontweight':500, 'size':12})
        plt.ylim(0,26)
        plt.xticks(order_day, rotation=0)
    fig.tight_layout(pad=2.0)
    plt.show()
sub_plot_weekday(dt1)

KeyError                                  Traceback (most recent call last)
File ~\AppData\Local\anaconda3\envs\myenv\lib\site-packages\pandas\core\indexes\base.py:3790, in Index.get_loc(self, key)
   3789 try:
-> 3790     return self._engine.get_loc(casted_key)
   3791 except KeyError as err:

File index.pyx:152, in pandas._libs.index.IndexEngine.get_loc()

File index.pyx:181, in pandas._libs.index.IndexEngine.get_loc()

File pandas\_libs\hashtable_class_helper.pxi:7080, in pandas._libs.hashtable.PyObjectHashTable.get_item()

File pandas\_libs\hashtable_class_helper.pxi:7088, in pandas._libs.hashtable.PyObjectHashTable.get_item()

KeyError: '2019-10'

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

KeyError                                  Traceback (most recent call last)
Cell In[11], line 1
----> 1 sub_plot_weekday(dt1)

Cell In[10], line 25, in sub_plot_weekday(df)
     21 #Recoremos cada "fecha" recogida
     23 for d in range(len(fechas)):
     24     #Guardamos en una var el df filtrado x fecha
---> 25     filter_df = df[fechas[d]].copy()
     26     #Guardamos en una lista el nombre de cada día para cada "Fecha" y la ponemos en una columna
     27     #print(filter_df)
     28     dates = filter_df.index

File ~\AppData\Local\anaconda3\envs\myenv\lib\site-packages\pandas\core\frame.py:3896, in DataFrame.__getitem__(self, key)
   3894 if self.columns.nlevels > 1:
   3895     return self._getitem_multilevel(key)
-> 3896 indexer = self.columns.get_loc(key)
   3897 if is_integer(indexer):
   3898     indexer = [indexer]

File ~\AppData\Local\anaconda3\envs\myenv\lib\site-packages\pandas\core\indexes\base.py:3797, in Index.get_loc(self, key)
   3792     if isinstance(casted_key, slice) or (
   3793         isinstance(casted_key, abc.Iterable)
   3794         and any(isinstance(x, slice) for x in casted_key)
   3795     ):
   3796         raise InvalidIndexError(key)
-> 3797     raise KeyError(key) from err
   3798 except TypeError:
   3799     # If we have a listlike key, _check_indexing_error will raise
   3800     #  InvalidIndexError. Otherwise we fall through and re-raise
   3801     #  the TypeError.
   3802     self._check_indexing_error(key)

KeyError: '2019-10'

Servy · Answer

错误 KeyError: '2019-10' 意味着在DataFrame的索引中找不到 '2019-10'。这个错误发生在代码行 filter_df = df[fechas[d]].copy() 处。在这里，您正试图根据 fechas 列表中存储的日期来过滤 DataFrame df。如果您的DataFrame索引是一个DateTimeIndex，并且您尝试用日期的字符串表示来访问它，请确保格式完全匹配。如果 '2019-10' 并不在索引中，这就会导致 KeyError 错误。

为了调试，建议打印出您的DataFrame的索引和 fechas 列表，以验证日期及其格式。确保 fechas 列表中的日期出现在DataFrame的索引中，并且格式一致。如果DataFrame的索引不是DateTimeIndex，考虑将其转换为DateTimeIndex以便于基于日期的过滤操作。

希望这对您有所帮助。
祝好。

Macarse · Answer

我认为你需要使用 .loc：

for d in range(len(fechas)):
    filter_df = df.loc[fechas[d]].copy()  # <- 在这里修改
    print(filter_df)

输出结果将会是：

            weekday
2019-10-15        1
2019-10-15        1
2019-10-16        2
2019-10-27        6

            weekday
2019-11-24        6
2019-11-26        1

在fechas中，我有这些日期：['2019-10', '2019-11', '2019-12', '2020-01', '2020-02']，而DataFrame的前五行索引是这样的：DatetimeIndex(['2019-10-15', '2019-10-15', '2019-10-15', '2019-10-15', '2019-10-15'], dtype='datetime64[ns]', name='datetime', freq=None)。

最小可复现示例（Minimal Working Example）:

fechas = ['2019-10', '2019-11']
dti = pd.DatetimeIndex(['2019-10-15', '2019-10-15', '2019-10-16',
                        '2019-11-24', '2019-11-26', '2019-10-27'])
df = pd.DataFrame({'weekday': dti.weekday}, index=dti)
print(df)

# 输出
            weekday
2019-10-15        1
2019-10-15        1
2019-10-16        2
2019-11-24        6
2019-11-26        1
2019-10-27        6