擅长:python、mysql、java
<p>使用<a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.sign.html" rel="nofollow noreferrer">np.sign()</a>方法:</p>
<pre><code>In [22]: df['a'] = np.sign(df.value)
In [23]: df
Out[23]:
timestamp value a
0 2000-01-03 00:00:00 25 1
1 2000-01-03 00:30:00 -10 -1
2 2000-01-03 01:00:00 100 1
3 2000-01-03 01:30:00 -690 -1
4 2000-01-03 02:00:00 650 1
5 2000-01-03 02:30:00 320 1
6 2000-01-03 03:00:00 150 1
7 2000-01-03 03:30:00 160 1
8 2000-01-03 04:00:00 0 0 # < -
</code></pre>
<p>注意:<code>np.sign</code>-对于<code>0</code>值返回{<cd2>},如果您想让<code>-1</code>作为零值,请使用<a href="https://docs.scipy.org/doc/numpy/reference/generated/numpy.where.html" rel="nofollow noreferrer">np.where()</a>:</p>
^{pr2}$