pandas reindex method='pad' 在 MultiIndex 中无法正常工作

Question

我想重新索引两列（字符串和 datetime64）的 Multiindex。但是，方法板没有按我的预期工作。

我的代码如下：

df = pd.read_csv('./Artikelstatus.csv',
                 sep=';',
                 parse_dates=['VON_DTM'],
                 infer_datetime_format=True,
                 usecols=['Artikel','ATTRIBUT','VON_DTM'],
                 dtype={'Artikel': 'str', 'ATTRIBUT': 'str'})

df["normalized_date"] = df["VON_DTM"].dt.floor("D")

min_dat = min(df['normalized_date'])
max_dat = np.datetime64(datetime.now().date())

articles = df['Artikel'].unique()
dates = np.arange(min_dat, max_dat, step=np.timedelta64(1,'D'))
df = df.set_index(['Artikel','VON_DTM']).groupby(['Artikel','normalized_date']).first()
index = pd.MultiIndex.from_product([articles, dates],names=['Artikel', 'normalized_date'])


df.info()
print(df.query('Artikel == "00017"'))
df = df.reindex(index, method='pad')
df.info()
print(df.query('Artikel == "00017" & normalized_date >= "2018-10-01" & normalized_date <= "2018-11-25"'))

输出如下所示

<class 'pandas.core.frame.DataFrame'>
MultiIndex: 13265 entries, (00017, 2018-10-01 00:00:00) to (25003, 2018-11-22 00:00:00)
Data columns (total 1 columns):
ATTRIBUT    13265 non-null object
dtypes: object(1)
memory usage: 170.5+ KB
                        ATTRIBUT
Artikel normalized_date         
00017   2018-10-01             0
        2018-11-21             3
<class 'pandas.core.frame.DataFrame'>
MultiIndex: 834065 entries, (00017, 2018-10-01 00:00:00) to (25003, 2020-03-18 00:00:00)
Data columns (total 1 columns):
ATTRIBUT    833877 non-null object
dtypes: object(1)
memory usage: 9.6+ MB
                        ATTRIBUT
Artikel normalized_date         
00017   2018-10-01             3
        2018-10-02             3
...
        2018-11-01             3
        2018-11-02           NaN
        2018-11-03           NaN
        2018-11-04           NaN
        2018-11-05           NaN
        2018-11-06             0
        2018-11-07             3
        2018-11-08             3
...
        2018-11-25             3

我希望 ATTRIBUT 的值从 0 开始，并在日期 2018-11-21 更改为 3。我错过了什么吗？

Answer 1

看来我找到了替换的解决方案

df = df.reindex(index, method='pad')

与

df = df.reindex(index)
df["ATTRIBUT"] = df["ATTRIBUT"].unstack(0).fillna(method = 'pad').unstack()

现在它正在按预期工作。