https://ruby-china.org/sunjohn en-us <p>实验数据 40000 个左右，存为一个 txt 文件中，每行一个数据： 想要每隔 100 行取一个数据，结果输出为 txt 文档 请问用 ruby 如何实现？</p> sunjohn Tue, 08 Jan 2013 17:14:32 +0800 https://ruby-china.org/topics/7882 https://ruby-china.org/topics/7882 <p>看 ruby 元编程，读到 instance_eval() 方法时，作者说他会打破封装，没有什么数据时私有的了。 那么有没有啥办法避免这种状况？</p> sunjohn Thu, 18 Oct 2012 09:39:21 +0800 https://ruby-china.org/topics/6137 https://ruby-china.org/topics/6137 <p>从 <code>array = [1, 2, 3, 4, 5]</code> 中随机选择 n 个数，这 n 个数的结果要以数组给出。</p> <p>写了个 method <code>def select_random(array, n)</code> <code>array.shuffle.drop(array.size - n)</code> <code>end</code></p> <p>觉得有点怪，麻烦各位给看下，有没有好的方法，谢谢啊！</p> sunjohn Sun, 14 Oct 2012 10:28:34 +0800 https://ruby-china.org/topics/6045 https://ruby-china.org/topics/6045 <p>任意长度的数组，如何实现累减？ 如： <code>[1, 2, 3, 4, 5]</code> 计算结果为： -13 我用的是这个：</p> <pre class="highlight ruby"><code><span class="k">def</span> <span class="nf">subtract</span><span class="p">(</span><span class="o">*</span><span class="n">nums</span><span class="p">)</span> <span class="n">nums</span><span class="p">.</span><span class="nf">inject</span><span class="p">(</span><span class="mi">2</span> <span class="o">*</span> <span class="n">nums</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span> <span class="p">{</span> <span class="o">|</span><span class="n">sum</span><span class="p">,</span> <span class="n">n</span><span class="o">|</span> <span class="n">sum</span> <span class="o">-</span> <span class="n">n</span> <span class="p">}</span> <span class="k">end</span> </code></pre> <p>但是感觉很别扭，有没有更简单的？</p> sunjohn Fri, 12 Oct 2012 11:17:20 +0800 https://ruby-china.org/topics/6018 https://ruby-china.org/topics/6018