擅长:python、mysql、java
<p>这正是<a href="http://docs.scipy.org/doc/numpy/reference/generated/numpy.repeat.html" rel="noreferrer">^{<cd1>}</a>的作用:</p>
<pre><code>>>> a = np.array([0.1, 0.2, 0.3, 0.4, 0.5, 0.6])
>>> s = np.array([3, 3, 9, 3, 6, 3])
>>> np.repeat(a, s)
array([ 0.1, 0.1, 0.1, 0.2, 0.2, 0.2, 0.3, 0.3, 0.3, 0.3, 0.3,
0.3, 0.3, 0.3, 0.3, 0.4, 0.4, 0.4, 0.5, 0.5, 0.5, 0.5,
0.5, 0.5, 0.6, 0.6, 0.6])
</code></pre>
<p>在纯Python中,您可以执行以下操作:</p>
^{pr2}$
<p>当然,它会比它的NumPy等同物慢得多:</p>
<pre><code>>>> s = [3, 3, 9, 3, 6, 3]*1000
>>> a = [0.1, 0.2, 0.3, 0.4, 0.5, 0.6]*1000
>>> %timeit list(chain.from_iterable(imap(repeat, a, s)))
1000 loops, best of 3: 1.21 ms per loop
>>> %timeit np.repeat(a_a, s_a) #a_a and s_a are NumPy arrays of same size as a and b
10000 loops, best of 3: 202 µs per loop
</code></pre>