Python 关键字 lambda

lambda 参数1, 参数2,... : 表达式

add = lambda x, y: x + y
print(add(1, 2))

num_list = [1, 2, 3]
squared_list = list(map(lambda x: x ** 2, num_list))
print(squared_list)  # [1, 4, 9]

num_list = [1, 2, 3, 4]
# 判断是否为偶数
even_numbers_list = list(filter(lambda x: x % 2 == 0, num_list))
print(even_numbers_list)  # [2, 4]

<h2><a id="_0"></a>前言</h2> <p>lambda 是python用于创建<strong>匿名函数</strong>的一种表达式。</p> <p>语法</p> <pre><div class="hljs"><code class="lang-python"><span class="hljs-keyword">lambda</span> 参数<span class="hljs-number">1</span>, 参数<span class="hljs-number">2</span>,... : 表达式 </code></div></pre> <h2><a id="1__14"></a>1 基础案例</h2> <pre><div class="hljs"><code class="lang-python">add = <span class="hljs-keyword">lambda</span> x, y: x + y <span class="hljs-built_in">print</span>(add(<span class="hljs-number">1</span>, <span class="hljs-number">2</span>)) </code></div></pre> <h2><a id="2_map_23"></a>2 与map一起使用</h2> <p>map：对每个参数进行处理</p> <pre><div class="hljs"><code class="lang-python">num_list = [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>] squared_list = <span class="hljs-built_in">list</span>(<span class="hljs-built_in">map</span>(<span class="hljs-keyword">lambda</span> x: x ** <span class="hljs-number">2</span>, num_list)) <span class="hljs-built_in">print</span>(squared_list) <span class="hljs-comment"># [1, 4, 9]</span> </code></div></pre> <p><img src="https://static.couragesteak.com/article/836c208d52ea84b0350073caace49e05.png" alt="lambda与map一起使用" /></p> <h2><a id="3_filter_35"></a>3 与filter一起使用</h2> <p>filter： 取符合条件的</p> <pre><div class="hljs"><code class="lang-python">num_list = [<span class="hljs-number">1</span>, <span class="hljs-number">2</span>, <span class="hljs-number">3</span>, <span class="hljs-number">4</span>] <span class="hljs-comment"># 判断是否为偶数</span> even_numbers_list = <span class="hljs-built_in">list</span>(<span class="hljs-built_in">filter</span>(<span class="hljs-keyword">lambda</span> x: x % <span class="hljs-number">2</span> == <span class="hljs-number">0</span>, num_list)) <span class="hljs-built_in">print</span>(even_numbers_list) <span class="hljs-comment"># [2, 4]</span> </code></div></pre> <p><img src="https://static.couragesteak.com/article/4ec6a548855c0ac18f8ae852b2288e75.png" alt="lambda与filter一起使用" /></p>