擅长:python、mysql、java
<p>将DataFrame<strong>prior</strong>的行顺序反转为grouping,以便在每个月内以相反顺序计算<code>cumsum</code>。你知道吗</p>
<pre><code>df['inv_workable_day'] = df[::-1].groupby('month')['flag_workable'].cumsum()
df['workable_day'] = df.groupby('month')['flag_workable'].cumsum()
# Date flag_workable month inv_workable_day workable_day
#1 2019-01-02 True 1 5.0 1.0
#2 2019-01-03 True 1 4.0 2.0
#3 2019-01-04 True 1 3.0 3.0
#6 2019-01-07 True 1 2.0 4.0
#7 2019-01-08 True 1 1.0 5.0
#8 2019-02-01 True 2 1.0 1.0
</code></pre>