{"id":156,"date":"2016-04-12T21:31:47","date_gmt":"2016-04-12T13:31:47","guid":{"rendered":"http:\/\/www.5x44.cn\/?p=156"},"modified":"2016-04-12T21:31:47","modified_gmt":"2016-04-12T13:31:47","slug":"8-6-itertools%e6%a8%a1%e5%9d%97","status":"publish","type":"post","link":"https:\/\/www.5x44.cn\/?p=156","title":{"rendered":"8.6 itertools\u6a21\u5757"},"content":{"rendered":"

\u672c\u6765\u5e94\u8be5\u53eb\u201c\u8ba1\u7b97\u6392\u5217\u7684\u61d2\u65b9\u6cd5\u201d\u4f46\u662f\u6211\u89c9\u5f97\u53ef\u4ee5\u548c\u4e0b\u4e00\u8282\u5408\u5e76\uff0c\u5c31\u6539\u4e86\u4e00\u4e2a\u6807\u9898\u3002<\/p>\n

\uff081\uff09\u8ba1\u7b97\u6392\u5217\u7684\u61d2\u65b9\u6cd5<\/p>\n

>>> import itertools\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u2460<\/code>
\n>>> perms = itertools.permutations([1, 2, 3], 2) \u2461<\/code>
\n>>> next(perms)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u2462<\/code>
\n(1, 2)<\/code>
\n>>> next(perms)<\/code>
\n(1, 3)<\/code>
\n>>> next(perms)<\/code>
\n(2, 1)\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \u2463<\/code>
\n>>> next(perms)<\/code>
\n(2, 3)<\/code>
\n>>> next(perms)<\/code>
\n(3, 1)<\/code>
\n>>> next(perms)<\/code>
\n(3, 2)<\/code>
\n>>> next(perms) \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0 \u2464<\/code>
\nTraceback (most recent call last):<\/code>
\nFile \"<stdin>\", line 1, in <module><\/code>
\nStopIteration<\/code><\/p>\n

    \n
  1. itertools\u6a21\u5757\u6709\u5f88\u591a\u6709\u8da3\u7684\u5de5\u5177\uff0c\u5305\u542bpermutations()\u51fd\u6570\uff0c\u5b83\u53ef\u4ee5\u627e\u5230\u6240\u6709\u7ec4\u5408\u3002<\/li>\n
  2. permutations()\u51fd\u6570\u6709\u4e24\u4e2a\u53c2\u6570\uff0c\u662f\u4e00\u7ec4\u5e8f\u5217\u548c\u4e00\u4e2a\u6570\u5b57\uff0c\u8fd9\u4e2a\u6570\u5b57\u662f\u4f60\u6240\u5e0c\u671b\u7684\u7ec4\u5408\u4e2d\u6709\u51e0\u4e2a\u5143\u7d20\u3002\u8fd9\u4e2a\u51fd\u6570\u8fd4\u56de\u4e00\u4e2a\u8fed\u4ee3\u5668\uff0c\u4e5f\u5c31\u662f\u8bf4\u8fd4\u56de\u7684\u503c\uff0c\u53ef\u4ee5\u7528\u5728for\u5faa\u73af\u4e2d\uff0c\u6216\u4efb\u4f55\u53ef\u4ee5\u7528\u8fed\u4ee3\u5668\u7684\u5730\u65b9\u3002<\/li>\n
  3. \u7b2c\u4e00\u6b21\u8ba1\u7b97\u7ec4\u5408\u8fd4\u56de\u4e86\uff081\uff0c2\uff09<\/li>\n
  4. \u6ce8\u610f\u5728\u7ec4\u5408\u4e2d\uff082\uff0c1\uff09\u548c\uff081\uff0c2\uff09\u662f\u4e0d\u540c\u7684\u3002<\/li>\n
  5. \u50cf\uff081\uff0c1\uff09\uff0c\uff082\uff0c2\uff09\u8fd9\u4e0d\u662f\u6709\u6548\u7684\u7ec4\u5408\uff0c\u6240\u4ee5\u4e0d\u4f1a\u88ab\u5217\u51fa\u3002\u5f53\u6240\u6709\u7684\u7ec4\u5408\u90fd\u8ba1\u7b97\u5b8c\u6bd5\u540e\uff0c\u5982\u679c\u7ee7\u7eed\u8fed\u4ee3\uff0c\u4f1a\u5f15\u53d1StopIteration\u5f02\u5e38\u3002<\/li>\n<\/ol>\n

    \u6ce8\u610f\uff1apermutations()\u51fd\u6570\u4e0d\u662f\u4e00\u5b9a\u8981\u7528list\uff0c\u5b83\u53ef\u4ee5\u662f\u4efb\u4f55\u5e8f\u5217\u2014\u2014\u751a\u81f3\u662f\u5b57\u7b26\u4e32\u3002<\/p>\n

    \uff082\uff09\u8ba1\u7b97\u7ec4\u5408\u7684\u7684\u5de5\u5177<\/p>\n

    >>> list(itertools.combinations(‘ABC’, 2))
    \n[(‘A’, ‘B’), (‘A’, ‘C’), (‘B’, ‘C’)]<\/p>\n

    \u5728\u6570\u5b66\u4e0a\u6392\u5217\u662f\u6709\u5148\u540e\u987a\u5e8f\u7684\uff0c\u4e5f\u5c31\u662f\uff081\uff0c2\uff09\u548c\uff082\uff0c1\uff09\u662f\u4e0d\u540c\u7684\uff0c\u4f46\u7ec4\u5408\u6ca1\u6709\u987a\u5e8f\u4e5f\u5c31\u662f\uff081\uff0c2\uff09\u548c\uff082\uff0c1\uff09\u662f\u76f8\u540c\u7684\u3002<\/p>\n

    \uff083\uff09itertools.groupby(iterable, key = None)<\/code>\u5206\u7ec4\u51fd\u6570\uff0c\u6839\u636e\u67d0\u4e2a\u51fd\u6570\u65b9\u6cd5\u5bf9\u5e8f\u5217\u8fdb\u884c\u5206\u7ec4\u3002<\/p>\n

    \u751f\u6210\u4e00\u4e2a\u8fed\u4ee3\u5668\uff0c\u5b83\u80fd\u4eceiterable\u4e2d\u8fd4\u56de\u4e00\u4e2a\u8fde\u7eed\u7684\u5173\u952e\u5b57\u548c\u5206\u7ec4\u3002\u5176\u4e2d\u7684key\u662f\u4e00\u4e2a\u51fd\u6570\uff0c\u53ef\u4ee5\u4e3a\u6bcf\u4e2a\u5143\u7d20\u8ba1\u7b97\u5173\u952e\u503c\uff08key value\uff09\u3002\u901a\u5e38iterable\u662f\u6839\u636ekey\u51fd\u6570\u6392\u5e8f\u8fc7\u7684\u3002\u5982\u679ckey\u4e3a\u7a7a\u6216\u672a\u8bbe\u7f6e\uff0c\u5c31\u4f1a\u8fd4\u56de\u672a\u6539\u53d8\u8fc7\u7684\u5143\u7d20\u3002<\/p>\n

    \uff084\uff09itertools.chain(iterator1,iterator2)<\/code>\u94fe\u63a5\u4e24\u4e2a\u8fed\u4ee3\u5668<\/p>\n

    >>> list(itertools.chain(range(0, 3), range(10, 13)))
    \n[0, 1, 2, 10, 11, 12]<\/p>\n

    \u5b83\u53ef\u4ee5\u628a\u7b2c\u4e00\u4e2a\u8fed\u4ee3\u5668\u548c\u7b2c\u4e8c\u4e2a\u8fed\u4ee3\u5668\u94fe\u63a5\u5728\u4e00\u8d77\uff0c\u8fd4\u56de\u4e00\u4e2a\u65b0\u7684\u8fed\u4ee3\u5668\uff0c\u8fd9\u4e2a\u65b0\u7684\u8fed\u4ee3\u5668\u53ef\u4ee5\u8fed\u4ee3\u5168\u90e8\u5143\u7d20\u3002<\/p>\n

    \uff085\uff09zip(iter1,iter2)<\/p>\n

    \u7ffb\u8bd1\u8d77\u6765\u597d\u96be~\u4e0d\u5199\u4e86\uff0c\u5f88\u56f0\u3002\u3002\u3002\u76f4\u63a5\u4e0a\u4f8b\u5b50\u5427\uff01
    \n>>> list(zip(range(0, 3), range(10, 13))) <\/code>
    \n[(0, 10), (1, 11), (2, 12)]<\/code><\/p>\n

     <\/p>\n

     <\/p>\n","protected":false},"excerpt":{"rendered":"

    \u672c\u6765\u5e94\u8be5\u53eb\u201c\u8ba1\u7b97\u6392\u5217\u7684\u61d2\u65b9\u6cd5\u201d\u4f46\u662f\u6211\u89c9\u5f97\u53ef\u4ee5\u548c\u4e0b\u4e00\u8282\u5408\u5e76\uff0c\u5c31\u6539\u4e86\u4e00\u4e2a\u6807\u9898\u3002 \uff081\uff09\u8ba1\u7b97\u6392\u5217\u7684\u61d2\u65b9\u6cd5 >>> import itertools\u00a0…<\/p>\n

    Read More 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-156","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\/156","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=156"}],"version-history":[{"count":1,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/156\/revisions"}],"predecessor-version":[{"id":157,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/156\/revisions\/157"}],"wp:attachment":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=156"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=156"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=156"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}