<p>这个问题确实需要更多的细节来自信地回答,但由于有一个常见的错误可能会产生这种奇怪的结果(而且由于我无法以任何其他方式重现它)。。。你知道吗</p>
<p>我认为问题不在<code>createIndividual</code>函数中,而是在为它提供数据结构中。下面是我的<code>main</code>函数的一部分,它精确地生成了您期望的随机输出:</p>
<pre class="lang-python3 prettyprint-override"><code>from pprint import pprint
# pprint is essential for pretty-printing deeply nested data.
class Table(object):
...
# Guesswork on my part, plus a custom __str__ and __repr__.
def main():
# This creates a list of two lists-of-three-Tables.
distinct_courses = [[Table() for __ in range(3)] for __ in range(2)]
filled_courses = createIndividual(distinct_courses)
pprint(filled_courses)
</code></pre>
<p>输出:</p>
<pre class="lang-python3 prettyprint-override"><code>[[Table([1, 2, 3]), Table([5, 8, 6]), Table([7, 4, 9])],
[Table([7, 5, 3]), Table([2, 6, 8]), Table([9, 1, 4])]]
</code></pre>
<p>为了重现您的问题,我必须使用列表乘法语法创建<code>courses</code>,这并不像大多数初学者(和一些教程)认为的那样:</p>
<blockquote>
<h2><a href="https://docs.python.org/3/library/stdtypes.html#typesseq-common" rel="nofollow">4.6.1. Common Sequence Operations</a></h2>
<p>[table omitted]</p>
<p>Notes:</p>
<ol start="2">
<li>[...] Note that items in the sequence <em>s</em> are not copied; they are referenced multiple times. This often haunts new Python programmers; [...]</li>
</ol>
<p>Further explanation is available in the FAQ entry <a href="https://docs.python.org/3/faq/programming.html#faq-multidimensional-list" rel="nofollow">How do I create a multidimensional list?</a>.</p>
</blockquote>
<p>我猜在你的代码里,你做了这样的事情:</p>
<pre class="lang-python3 prettyprint-override"><code>def bogus_main():
# This creates a single lists-of-three-Tables...
course = [Table() for __ in range(3)]
# ...then creates a list of two references to the _same_ list.
aliased_courses = [course] * 2
filled_courses = createIndividual(aliased_courses)
pprint(filled_courses)
</code></pre>
<p>使用别名列表输出:</p>
<pre class="lang-python3 prettyprint-override"><code>[[Table([7, 9, 2]), Table([8, 6, 1]), Table([5, 3, 4])],
[Table([7, 9, 2]), Table([8, 6, 1]), Table([5, 3, 4])]]
</code></pre>
<p>因为<code>courses[0]</code>和<code>courses[1]</code>都指向相同的<em>列表,所以发生了两件奇怪的事情。首先,“两个”<code>course</code>的内容将是相同的,正如您已经注意到的。每次更新似乎都会将一对相同的<code>Table</code>添加到两个不同的列表中,尽管实际上只是将一个<code>Table</code>添加到一个列表中。。。然后打印两次。。。您可以通过向<code>createIndividual</code>添加额外的<code>pprint</code>来看到这一点:</p>
<pre class="lang-python3 prettyprint-override"><code>[[Table([]), Table([]), Table([])],
[Table([]), Table([]), Table([])]]
[[Table([7, 9, 2]), Table([]), Table([])],
[Table([7, 9, 2]), Table([]), Table([])]]
[[Table([7, 9, 2]), Table([8, 6, 1]), Table([])],
[Table([7, 9, 2]), Table([8, 6, 1]), Table([])]]
[[Table([7, 9, 2]), Table([8, 6, 1]), Table([5, 3, 4])],
[Table([7, 9, 2]), Table([8, 6, 1]), Table([5, 3, 4])]]
[[Table([7, 9, 2]), Table([8, 6, 1]), Table([5, 3, 4])],
[Table([7, 9, 2]), Table([8, 6, 1]), Table([5, 3, 4])]]
[[Table([7, 9, 2]), Table([8, 6, 1]), Table([5, 3, 4])],
[Table([7, 9, 2]), Table([8, 6, 1]), Table([5, 3, 4])]]
[[Table([7, 9, 2]), Table([8, 6, 1]), Table([5, 3, 4])],
[Table([7, 9, 2]), Table([8, 6, 1]), Table([5, 3, 4])]]
</code></pre>
<p>第二,注意最后三个“更新”实际上并没有改变什么?当您尝试仅向9个插槽添加18个值时,某些<em>应该</em>失败。不幸的是,<code>maximum</code>字段可以保护您避免过度填充<code>Table</code>也可以避免出现可能会提前提示您的错误。从<code>createIndividual</code>:</p>
<pre class="lang-python3 prettyprint-override"><code>for table in course:
while len(table) < table.maximum:
# Once the "first" aliased course list is full, this will
# never pop another person, because there's no place to
# store them.
table.append(myPeople.pop())
print(len(myPeople)) # My addition.
# Prints 6, 3, and 0 during the first `course`, then prints
# 9, 9, and 9... myPeople never changes the second time through.
</code></pre>
<p>在“第一个”(实际上是唯一的)三个<code>Table</code>被填满之后,它们的长度都是<code>maximum</code>,因此<code>individual</code>或<code>myPeople</code>都不会再改变。你知道吗</p>
<p>对比一下我的<code>main</code>中的列表理解版本,它创建了六个不同的<code>Table</code>对象,如您所料:</p>
<pre class="lang-python3 prettyprint-override"><code>[[Table([]), Table([]), Table([])],
[Table([]), Table([]), Table([])]]
[[Table([1, 2, 3]), Table([]), Table([])],
[Table([]), Table([]), Table([])]]
[[Table([1, 2, 3]), Table([5, 8, 6]), Table([])],
[Table([]), Table([]), Table([])]]
[[Table([1, 2, 3]), Table([5, 8, 6]), Table([7, 4, 9])],
[Table([]), Table([]), Table([])]]
[[Table([1, 2, 3]), Table([5, 8, 6]), Table([7, 4, 9])],
[Table([7, 5, 3]), Table([]), Table([])]]
[[Table([1, 2, 3]), Table([5, 8, 6]), Table([7, 4, 9])],
[Table([7, 5, 3]), Table([2, 6, 8]), Table([])]]
[[Table([1, 2, 3]), Table([5, 8, 6]), Table([7, 4, 9])],
[Table([7, 5, 3]), Table([2, 6, 8]), Table([9, 1, 4])]]
</code></pre>