Question

我有一个pandas数据框df，每行包含start_date（也是索引）和duration（以天为单位）订阅。

import pandas as pd    
df = pd.DataFrame({'start_date':['2018-01-01','2018-01-05']})
df['start_date'] = df['start_date'].astype('datetime64[ns]')
df['duration'] = pd.to_timedelta([10,8], unit='D')
df['end_date'] = df['start_date'] + df['duration']

我想绘制一段时间内的订阅者数量。

我的想法是创建另一个数据框subscribers：

active_subscribers = pd.DataFrame({
    'Date': pd.date_range(start=df.index.min(),end=df['end_date'].max()),
    'Number': 0,
})
active_subscribers.set_index('Date', inplace=True)

Date涵盖至少一个订户处于活动状态的整个时间段。然后我在考虑为每个订阅创建日期范围，并将其添加到Number列，如下所示：

for index, row in df.iterrows():
    for this_date in pd.date_range(start=index, end=row['end_date']):
        active_subscribers[this_date]['Number'] += 1

但这会返回以下错误：

KeyError: Timestamp('2018-01-01 00:00:00', freq='D')

我希望得到的是Number列，如下所示：

Date         Number
2018-01-01     1
2018-01-02     1
2018-01-03     1
2018-01-04     1
2018-01-05     2
2018-01-06     2
2018-01-07     2
2018-01-08     2
2018-01-09     2
2018-01-10     2
2018-01-11     1
2018-01-12     1
2018-01-13     1

列Number包含当天活跃订阅者的数量。

如果您有任何建议，请告诉我

Answer 1

您可以将列表理解与一起用于新DataFrame，然后通过itertuples和groupby获取新列：

df = pd.DataFrame(index=pd.to_datetime(['2018-01-01','2018-01-05']))
df['duration'] = pd.to_timedelta([10,8], unit='D')
df['end_date'] = df.index + df['duration']
print (df)
           duration   end_date
2018-01-01  10 days 2018-01-11
2018-01-05   8 days 2018-01-13

df = df.rename_axis('start_date').reset_index()
com = [pd.Series(r.Index,pd.date_range(r.start_date, r.end_date)) for r in df.itertuples()]
df1 = pd.concat(com).reset_index()
df1.columns=['Date','Number']
df1 = df1.groupby('Date')['Number'].size().reset_index()
print (df1)
         Date  Number
0  2018-01-01       1
1  2018-01-02       1
2  2018-01-03       1
3  2018-01-04       1
4  2018-01-05       2
5  2018-01-06       2
6  2018-01-07       2
7  2018-01-08       2
8  2018-01-09       2
9  2018-01-10       2
10 2018-01-11       2
11 2018-01-12       1
12 2018-01-13       1

iterrows解决方案更快：

In [288]: %timeit (iterrows_sol(df))
10 loops, best of 3: 51.1 ms per loop

In [289]: %timeit (itertupl_sol(df))
100 loops, best of 3: 10.2 ms per loop

样品：

df = pd.DataFrame(index=pd.to_datetime(['2018-01-01','2018-01-05'] * 10))
df['duration'] = pd.to_timedelta([10,8,2,3,7,2,1,9,1,20,7,18,9,0,3,20,10,8,3,15] , unit='D')
df['end_date'] = df.index + df['duration']
print (df)
           duration   end_date
2018-01-01  10 days 2018-01-11
2018-01-05   8 days 2018-01-13
2018-01-01   2 days 2018-01-03
2018-01-05   3 days 2018-01-08
2018-01-01   7 days 2018-01-08
2018-01-05   2 days 2018-01-07
2018-01-01   1 days 2018-01-02
2018-01-05   9 days 2018-01-14
2018-01-01   1 days 2018-01-02
2018-01-05  20 days 2018-01-25
2018-01-01   7 days 2018-01-08
2018-01-05  18 days 2018-01-23
2018-01-01   9 days 2018-01-10
2018-01-05   0 days 2018-01-05
2018-01-01   3 days 2018-01-04
2018-01-05  20 days 2018-01-25
2018-01-01  10 days 2018-01-11
2018-01-05   8 days 2018-01-13
2018-01-01   3 days 2018-01-04
2018-01-05  15 days 2018-01-20

功能：

def iterrows_sol(df):
    active_subscribers = pd.DataFrame({
    'Date': pd.date_range(start=df.index.min(), end=df['end_date'].max()),
    'Number': 0,})

    active_subscribers.set_index('Date', inplace=True)

    for index, row in df.iterrows():
        for this_date in pd.date_range(start=index, end=row['end_date']):
            active_subscribers.loc[this_date, 'Number'] += 1
    return active_subscribers

def itertupl_sol(df):
    df = df.rename_axis('start_date').reset_index()
    com = [pd.Series(r.Index,pd.date_range(r.start_date,r.end_date)) for r in df.itertuples()]
    df1 = pd.concat(com).reset_index()
    df1.columns=['Date','Number']
    df1 = df1.groupby('Date')['Number'].size().reset_index()
    return (df1)

python pandas从订阅开始日期和持续时间获取活动订阅者数

1 个答案: