擅长:python、mysql、java
<p>如果列表是随机排列的,你可以只取前50个</p>
<p>否则,请使用</p>
<pre><code>import random
random.sample(the_list, 50)
</code></pre>
<p><code>random.sample</code>帮助文本:</p>
<pre><code>sample(self, population, k) method of random.Random instance
Chooses k unique random elements from a population sequence.
Returns a new list containing elements from the population while
leaving the original population unchanged. The resulting list is
in selection order so that all sub-slices will also be valid random
samples. This allows raffle winners (the sample) to be partitioned
into grand prize and second place winners (the subslices).
Members of the population need not be hashable or unique. If the
population contains repeats, then each occurrence is a possible
selection in the sample.
To choose a sample in a range of integers, use xrange as an argument.
This is especially fast and space efficient for sampling from a
large population: sample(xrange(10000000), 60)
</code></pre>