python - 如何延长 pandas 数据框中的日期

Question

我有以下数据框。如何将接下来的 n=6 个月添加到日期末尾并指定新值=0。我运行以下代码，但会出现错误。

from pandas import DataFrame
import numpy as np
from datetime import timedelta
import calendar


date=['2000-01-01','2000-02-01','2000-03-01','2000-04-01','2000-05-01','2000-06-01','2000-07-01' ]
value=[5,6,2,7,5,6,2]
df = pd.DataFrame(list(zip(date,value)),columns =['date','value'])

df['date'] = pd.to_datetime(df['date'], format='%Y-%m-%d')


n=6
end_point = len(df)
x =df.at[end_point - 1, 'date']
days_in_month=calendar.monthrange(x.year, x.month)[1]

for i in range(n):
    df.at[df.index[end_point + i], 'date'] = x + timedelta(days=days_in_month + days_in_month * i)
    df.at[df.index[end_point + i], 'value'] = 0

Answer 1

IIUC，您可以使用date_range :

dti = pd.date_range(df['date'].max() + pd.offsets.MonthBegin(1), periods=6, freq='MS')
out = pd.concat([df, pd.DataFrame({'date': dti, 'value': 0})], ignore_index=True)

输出:

>>> out
         date  value
0  2000-01-01      5
1  2000-02-01      6
2  2000-03-01      2
3  2000-04-01      7
4  2000-05-01      5
5  2000-06-01      6
6  2000-07-01      2
7  2000-08-01      0
8  2000-09-01      0
9  2000-10-01      0
10 2000-11-01      0
11 2000-12-01      0
12 2001-01-01      0