Question

我有一个熊猫数据框，需要过滤，就像特定月份的sql查询一样。每次运行代码时，无论本月的具体日期是什么，我都希望它从上个月获取数据。

我的SQL代码在这里，但我需要等效的熊猫。

WHERE DATEPART(m, logged) = DATEPART(m, DATEADD(m, -1, getdate()))

df = pd.DataFrame({'month': ['1-05-01 00:00:00','1-06-01 00:00:00','1-06-01 00:00:00','1-05-01 00:00:00']})
df['month'] = pd.to_datetime(df['month'])```

In this example, I only want the data from June. 
Would definitely appreciate the help!  Thanks.

Answer 1

根据问题进行修改：

df = pd.DataFrame({'month': ['1-05-01 00:00:00','1-06-01 00:00:00','1-06-01 00:00:00','1-05-01 00:00:00']})
df['month'] = pd.to_datetime(df['month'])  

## To get it to the right format
import datetime as dt
df['month'] = df['month'].apply(lambda x: dt.datetime.strftime(x, '%Y-%d-%m'))
df['month'] = pd.to_datetime(df['month'])  

## Extract the month from this date
df['month_ex'] = df.month.dt.month

## Get current month to get the latest month from the dataframe, which is the previous month of the current month
from datetime import datetime
currentMonth = datetime.now().month

newDf = df[df.month_ex == currentMonth - 1]

输出：

       month  month_ex
1 2001-06-01         6
2 2001-06-01         6

熊猫相当于月份日期时间的sql

1 个答案: