{"id":154,"date":"2016-04-12T20:08:14","date_gmt":"2016-04-12T12:08:14","guid":{"rendered":"http:\/\/www.5x44.cn\/?p=154"},"modified":"2019-01-21T16:05:49","modified_gmt":"2019-01-21T08:05:49","slug":"8-5-generator-experssion-%e7%94%9f%e6%88%90%e5%99%a8%e8%a1%a8%e8%be%be%e5%bc%8f","status":"publish","type":"post","link":"https:\/\/www.5x44.cn\/?p=154","title":{"rendered":"8.5 Generator Experssion\u2014\u2014\u751f\u6210\u5668\u8868\u8fbe\u5f0f"},"content":{"rendered":"<p>generator\u662f\u4e00\u4e2a\u7528\u4e8e\u521b\u5efaiterator\u7684\u7b80\u5355\u5e76\u5f3a\u5927\u7684\u5de5\u5177\u3002\u751f\u6210\u5668\u8868\u8fbe\u5f0f\u5c31\u50cf\u51fd\u6570\u4e00\u6837\uff0c\u4f46\u5b83\u4e0d\u662f\u4e00\u4e2a\u51fd\u6570\uff0c\u5b83\u4f7f\u7528yield\u8bed\u53e5\u8fd4\u56de\u6570\u636e\uff0c\u800c\u4e0d\u662f\u7528return\u3002<\/p>\n<p>\u4f7f\u7528yield\u7684\u6590\u6ce2\u90a3\u5951\u6570\u5217\uff1a<\/p>\n<div class=\"container\">\n<div class=\"line number1 index0 alt2\"><code class=\"htmlscript plain\">def fab(max): <\/code><\/div>\n<div class=\"line number2 index1 alt1\"><code class=\"htmlscript spaces\">\u00a0\u00a0\u00a0\u00a0<\/code><code class=\"htmlscript plain\">n, a, b = 0, 0, 1 <\/code><\/div>\n<div class=\"line number3 index2 alt2\"><code class=\"htmlscript spaces\">\u00a0\u00a0\u00a0\u00a0<\/code><code class=\"htmlscript plain\">while n &lt; max: <\/code><\/div>\n<div class=\"line number4 index3 alt1\"><code class=\"htmlscript spaces\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code><code class=\"htmlscript plain\">yield b <\/code><\/div>\n<div class=\"line number5 index4 alt2\"><code class=\"htmlscript spaces\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code><code class=\"htmlscript plain\"># print b <\/code><\/div>\n<div class=\"line number6 index5 alt1\"><code class=\"htmlscript spaces\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code><code class=\"htmlscript plain\">a, b = b, a + b <\/code><\/div>\n<div class=\"line number7 index6 alt2\"><code class=\"htmlscript spaces\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/code><code class=\"htmlscript plain\">n = n + 1 <\/code><\/div>\n<div class=\"line number9 index8 alt2\">\u7b80\u5355\u5730\u8bb2\uff0cyield \u7684\u4f5c\u7528\u5c31\u662f\u628a\u4e00\u4e2a\u51fd\u6570\u53d8\u6210\u4e00\u4e2a generator\uff0c\u5e26\u6709 yield \u7684\u51fd\u6570\u4e0d\u518d\u662f\u4e00\u4e2a\u666e\u901a\u51fd\u6570\uff0cPython \u89e3\u91ca\u5668\u4f1a\u5c06\u5176\u89c6\u4e3a\u4e00\u4e2a generator\uff0c\u8c03\u7528 fab(5) \u4e0d\u4f1a\u6267\u884c fab \u51fd\u6570\uff0c\u800c\u662f\u8fd4\u56de\u4e00\u4e2a iterable \u5bf9\u8c61\uff01\u5728 for \u5faa\u73af\u6267\u884c\u65f6\uff0c\u6bcf\u6b21\u5faa\u73af\u90fd\u4f1a\u6267\u884c fab \u51fd\u6570\u5185\u90e8\u7684\u4ee3\u7801\uff0c\u6267\u884c\u5230 yield b \u65f6\uff0cfab \u51fd\u6570\u5c31\u8fd4\u56de\u4e00\u4e2a\u8fed\u4ee3\u503c\uff0c\u4e0b\u6b21\u8fed\u4ee3\u65f6\uff0c\u4ee3\u7801\u4ece yield b \u7684\u4e0b\u4e00\u6761\u8bed\u53e5\u7ee7\u7eed\u6267\u884c\uff0c\u800c\u51fd\u6570\u7684\u672c\u5730\u53d8\u91cf\u770b\u8d77\u6765\u548c\u4e0a\u6b21\u4e2d\u65ad\u6267\u884c\u524d\u662f\u5b8c\u5168\u4e00\u6837\u7684\uff0c\u4e8e\u662f\u51fd\u6570\u7ee7\u7eed\u6267\u884c\uff0c\u76f4\u5230\u518d\u6b21\u9047\u5230 yield\u3002<\/div>\n<\/div>\n<pre><\/pre>\n<p><code> &gt;&gt;&gt; unique_characters = {'E', 'D', 'M', 'O', 'N', 'S', 'R', 'Y'}<\/code><br \/>\n<code>&gt;&gt;&gt; gen = (ord(c) for c in unique_characters)\u00a0 \u2460<\/code><br \/>\n<code>&gt;&gt;&gt; gen\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u00a0 \u2461<\/code><br \/>\n<code>&lt;generator object &lt;genexpr&gt; at 0x00BADC10&gt;<\/code><br \/>\n<code>&gt;&gt;&gt; next(gen)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u2462<\/code><br \/>\n<code>69<\/code><br \/>\n<code>&gt;&gt;&gt; next(gen)<\/code><br \/>\n<code>68<\/code><br \/>\n<code>&gt;&gt;&gt; tuple(ord(c) for c in unique_characters) \u00a0 \u2463<\/code><br \/>\n<code>(69, 68, 77, 79, 78, 83, 82, 89)<\/code><\/p>\n<ol>\n<li>\u751f\u6210\u5668\u8868\u8fbe\u5f0f\u5c31\u50cf\u4e00\u4e2a\u533f\u540d\u7684\u51fd\u6570\uff0c\u5b83\u751f\u6210\uff08yield\uff09\u4e00\u4e2a\u503c\u3002\u8868\u8fbe\u5f0f\u5b83\u81ea\u5df1\u770b\u8d77\u6765\u5c31\u50cf\u4e00\u4e2alist comprehension\uff0c\u4f46\u662f\u5b83\u88ab\u5c01\u88c5\u5230\u5706\u62ec\u53f7\u91cc\u800c\u4e0d\u662f\u65b9\u62ec\u53f7\u3002<\/li>\n<li>\u751f\u6210\u5668\u8868\u8fbe\u5f0f\u8fd4\u56de\u4e00\u4e2a\u8fed\u4ee3\u5668\uff08iterator\uff09<\/li>\n<li>\u8c03\u7528next(gen)\u4ece\u8fed\u4ee3\u5668\u8fd4\u56de\u4e0b\u4e00\u4e2a\u503c\u3002<\/li>\n<li>\u53ea\u8981\u4f60\u559c\u6b22\uff0c\u4f60\u80fd\u8fed\u4ee3\u4efb\u53ef\u4e00\u4e2a\u53ef\u4ee5\u7684\u503c\uff0c\u5e76\u901a\u8fc7tuple()\u3001list()\u6216set()\u8fd4\u56de\u4e00\u4e2a\u5143\u7ec4\u3001\u5217\u8868\u6216\u96c6\u5408\u3002\u5728\u4eec\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\u4e0d\u9700\u8981\u989d\u5916\u7684\u62ec\u53f7\u53ea\u8981\u8f93\u5165<code>ord(c) for c in unique_characters<\/code>\u5230tuple()\u51fd\u6570\u4e2d\uff0cpython\u5c31\u80fd\u8ba1\u7b97\u51fa\u5b83\u662f\u4e00\u4e2a\u751f\u6210\u5668\u8868\u8fbe\u5f0f\u3002<\/li>\n<li>ord(c)\u51fd\u6570\u53ef\u4ee5\u8fd4\u56de\u4e00\u4e2a\u6574\u6570\uff0c\u8fd9\u4e2a\u6574\u6570\u662f\u8be5\u5b57\u7b26\u7684Unicode code point\u3002<\/li>\n<\/ol>\n<p><span style=\"color: #ff0000;\"><strong>\u5c0f\u63d0\u793a\uff1a\u4f7f\u7528\u751f\u6210\u5668\u8868\u8fbe\u5f0f\u4ee3\u66fflist comprehension\u53ef\u4ee5\u8282\u7701CPU\u548cRAM\u3002<\/strong><\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>generator\u662f\u4e00\u4e2a\u7528\u4e8e\u521b\u5efaiterator\u7684\u7b80\u5355\u5e76\u5f3a\u5927\u7684\u5de5\u5177\u3002\u751f\u6210\u5668\u8868\u8fbe\u5f0f\u5c31\u50cf\u51fd\u6570\u4e00\u6837\uff0c\u4f46\u5b83\u4e0d\u662f\u4e00\u4e2a\u51fd\u6570\uff0c\u5b83\u4f7f\u7528yield\u8bed\u53e5\u8fd4\u56de\u6570\u636e\uff0c\u800c\u4e0d\u662f\u7528retur&#8230;<\/p>\n<p class=\"read-more\"><a class=\"btn btn-default\" href=\"https:\/\/www.5x44.cn\/?p=154\"> Read More<span class=\"screen-reader-text\">  Read More<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-154","post","type-post","status-publish","format-standard","hentry","category-dive-into-python3"],"_links":{"self":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/154","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=154"}],"version-history":[{"count":4,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/154\/revisions"}],"predecessor-version":[{"id":5952,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/154\/revisions\/5952"}],"wp:attachment":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=154"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=154"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=154"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}