您可以用途：

# convert to datetime
date = pd.to_datetime(df['sale_date'])

# is the day a Monday (0 = Monday)?
m1 = date.dt.weekday.eq(0)
# is the week an "even" week?
m2 = date.dt.isocalendar().week.mod(2).eq(0)

# if both conditions are True, keep the row
out = df[m1&m2]

输出：

sale_date  count
0  2022-06-27    100
3  2022-07-11    150
5  2022-07-25    150

中间体：

sale_date  count  weekday  weekday.eq(0)  week  week.mod(2)  week.mod(2).eq(0)
0  2022-06-27    100        0           True    26            0               True
1  2022-07-01    150        4          False    26            0               True
2  2022-07-07    100        3          False    27            1              False
3  2022-07-11    150        0           True    28            0               True
4  2022-06-20    100        0           True    25            1              False
5  2022-07-25    150        0           True    30            0               True

df11=df1.resample("2w-mon",closed="left",on="sale_date")["count"].first().reset_index()
df11.assign(sale_date=df11.sale_date-pd.Timedelta(days=7))

输出：

sale_date  count
0 2022-06-27    100
1 2022-07-11    100
2 2022-07-25    150