<p>我们也可以使用<a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.cumsum.html" rel="nofollow noreferrer">^{<cd1>}</a>+<a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.clip.html" rel="nofollow noreferrer">^{<cd2>}</a>:</p>
<pre><code>df['Forecast']=(
df['Predictions'].cumsum()
.clip(0,1)
.where(df.index < df.ExpirationDate)
.fillna(0, downcast='infer')
)
print(df)
</code></pre>
<p><strong>输出</strong></p>
<pre><code> Predictions ExpirationDate Forecast
Date
2017-09-18 0 2017-10-20 0
2017-09-19 0 2017-10-20 0
2017-09-20 0 2017-10-20 0
2017-09-21 0 2017-10-20 0
2017-09-22 0 2017-10-20 0
2017-09-25 0 2017-10-20 0
2017-09-26 0 2017-10-20 0
2017-09-27 0 2017-10-20 0
2017-09-28 0 2017-10-20 0
2017-09-29 0 2017-10-20 0
2017-10-02 0 2017-10-20 0
2017-10-03 0 2017-10-20 0
2017-10-04 0 2017-10-20 0
2017-10-05 1 2017-10-20 1
2017-10-06 0 2017-10-20 1
2017-10-09 0 2017-10-20 1
2017-10-10 0 2017-10-20 1
2017-10-11 0 2017-10-20 1
2017-10-12 0 2017-10-20 1
2017-10-13 0 2017-10-20 1
2017-10-16 0 2017-10-20 1
2017-10-17 0 2017-10-20 1
2017-10-18 0 2017-10-20 1
2017-10-19 0 2017-10-20 1
2017-10-20 0 2017-10-20 0
</code></pre>