{"id":1196,"date":"2025-01-01T21:44:11","date_gmt":"2025-01-01T13:44:11","guid":{"rendered":"http:\/\/www.chan.ink\/?p=1196"},"modified":"2025-01-01T21:44:15","modified_gmt":"2025-01-01T13:44:15","slug":"%e3%80%90python%e6%a0%87%e5%87%86%e5%ba%93%e3%80%91%e6%a0%87%e5%87%86%e5%ba%93%e4%b9%8bitertools","status":"publish","type":"post","link":"http:\/\/www.chan.ink\/index.php\/2025\/01\/01\/%e3%80%90python%e6%a0%87%e5%87%86%e5%ba%93%e3%80%91%e6%a0%87%e5%87%86%e5%ba%93%e4%b9%8bitertools\/","title":{"rendered":"\u3010Python|\u6807\u51c6\u5e93\u3011\u6807\u51c6\u5e93\u4e4bitertools"},"content":{"rendered":"\n

itertools<\/code> \u662f Python \u7684\u4e00\u4e2a\u6807\u51c6\u5e93\u6a21\u5757\uff0c\u63d0\u4f9b\u4e86\u7528\u4e8e\u64cd\u4f5c\u8fed\u4ee3\u5668\u7684\u51fd\u6570\uff0c\u80fd\u591f\u9ad8\u6548\u5730\u5904\u7406\u5faa\u73af\u548c\u7ec4\u5408\u6570\u636e\u3002\u8fd9\u4e2a\u6a21\u5757\u7684\u51fd\u6570\u53ef\u4ee5\u5e2e\u52a9\u4f60\u751f\u6210\u5404\u79cd\u590d\u6742\u7684\u8fed\u4ee3\u6a21\u5f0f\uff0c\u5982\u6392\u5217\u3001\u7ec4\u5408\u3001\u7b1b\u5361\u5c14\u79ef\u7b49\uff0c\u4e14\u5927\u591a\u6570\u64cd\u4f5c\u90fd\u662f\u61d2\u52a0\u8f7d\u7684\uff0c\u5373\u5728\u9700\u8981\u65f6\u624d\u751f\u6210\u7ed3\u679c\uff0c\u8fd9\u4f7f\u5f97\u5b83\u4eec\u5728\u5904\u7406\u5927\u578b\u6570\u636e\u96c6\u65f6\u7279\u522b\u9ad8\u6548\u3002<\/p>\n\n\n\n

——————————————————————-<\/p>\n\n\n\n

itertools.combinations(iterable, r)<\/code> \u662f\u4e00\u4e2a\u7528\u4e8e\u751f\u6210 \u7ec4\u5408<\/strong> \u7684\u5de5\u5177\u51fd\u6570\u3002\u7ec4\u5408\u662f\u4e00\u79cd\u4ece\u96c6\u5408\u4e2d\u9009\u53d6\u5143\u7d20\u7684\u65b9\u6cd5\uff0c\u4e0d\u8003\u8651\u5143\u7d20\u7684\u6392\u5217\u987a\u5e8f\uff0c\u56e0\u6b64\u4e0d\u4f1a\u6709\u91cd\u590d\u7684\u5143\u7d20\u3002<\/p>\n\n\n\n

\n\n\n\n

\u51fd\u6570\u5b9a\u4e49<\/strong><\/h3>\n\n\n\n
itertools.combinations(iterable, r)<\/code><\/pre>\n\n\n\n
    \n
  • iterable<\/code><\/strong>\uff1a\u8f93\u5165\u7684\u53ef\u8fed\u4ee3\u5bf9\u8c61\uff0c\u4f8b\u5982\u5217\u8868\u3001\u5b57\u7b26\u4e32\u6216\u5176\u4ed6\u53ef\u8fed\u4ee3\u5bf9\u8c61\u3002<\/li>\n\n\n\n
  • r<\/code><\/strong>\uff1a\u4ece iterable<\/code> \u4e2d\u9009\u53d6\u7684\u5143\u7d20\u6570\u91cf\u3002<\/li>\n<\/ul>\n\n\n\n
    \u8fd4\u56de\u503c\u662f\u4e00\u4e2a \u8fed\u4ee3\u5668<\/strong>\uff0c\u5176\u4e2d\u6bcf\u4e2a\u5143\u7d20\u662f\u4e00\u4e2a\u5305\u542b r<\/code> \u4e2a\u9879\u76ee\u7684\u5143\u7ec4\u3002<\/p>\n\n\n\n
    \n\n\n\n
    \u7279\u70b9<\/strong><\/h3>\n\n\n\n
      \n
    1. \u65e0\u91cd\u590d<\/strong>\uff1a\u751f\u6210\u7684\u7ec4\u5408\u4e0d\u5305\u542b\u91cd\u590d\u9879\u3002<\/li>\n\n\n\n
    2. \u987a\u5e8f\u65e0\u5173<\/strong>\uff1a\u5373 (1, 2)<\/code> \u548c (2, 1)<\/code> \u88ab\u89c6\u4e3a\u540c\u4e00\u4e2a\u7ec4\u5408\uff0c\u7ed3\u679c\u4e2d\u53ea\u4f1a\u5305\u542b (1, 2)<\/code>\u3002<\/li>\n\n\n\n
    3. \u61d2\u52a0\u8f7d<\/strong>\uff1a\u53ea\u5728\u9700\u8981\u65f6\u751f\u6210\u7ec4\u5408\uff0c\u9002\u5408\u5927\u6570\u636e\u96c6\u3002<\/li>\n<\/ol>\n\n\n\n
      \n\n\n\n
      \u7528\u6cd5\u793a\u4f8b<\/strong><\/h3>\n\n\n\n
      1. \u4ece\u5217\u8868\u4e2d\u751f\u6210\u7ec4\u5408<\/h4>\n\n\n\n
      import itertools\n\ndata = [1, 2, 3, 4]\nresult = itertools.combinations(data, 2)\n\nfor combo in result:\n    print(combo)<\/code><\/pre>\n\n\n\n
      \u8f93\u51fa\uff1a<\/strong><\/p>\n\n\n\n
      (1, 2)\n(1, 3)\n(1, 4)\n(2, 3)\n(2, 4)\n(3, 4)<\/code><\/pre>\n\n\n\n
      \u89e3\u91ca\uff1a<\/p>\n\n\n\n
        \n
      • \u53d6\u957f\u5ea6\u4e3a 2 \u7684\u7ec4\u5408\uff0c\u5171\u6709 6 \u79cd\u53ef\u80fd\u3002<\/li>\n<\/ul>\n\n\n\n
        \n\n\n\n
        2. \u4ece\u5b57\u7b26\u4e32\u4e2d\u751f\u6210\u7ec4\u5408<\/h4>\n\n\n\n
        import itertools\n\ndata = \"ABC\"\nresult = itertools.combinations(data, 2)\n\nprint(list(result))<\/code><\/pre>\n\n\n\n
        \u8f93\u51fa\uff1a<\/strong><\/p>\n\n\n\n
        [('A', 'B'), ('A', 'C'), ('B', 'C')]<\/code><\/pre>\n\n\n\n
        \u89e3\u91ca\uff1a<\/p>\n\n\n\n
          \n
        • \u53d6\u957f\u5ea6\u4e3a 2 \u7684\u7ec4\u5408\uff0c\u5171\u6709 3 \u79cd\u53ef\u80fd\u3002<\/li>\n<\/ul>\n\n\n\n
          \n\n\n\n
          3. \u8f83\u5927\u7684\u7ec4\u5408\u6570<\/h4>\n\n\n\n
          import itertools\n\ndata = range(5)  # [0, 1, 2, 3, 4]\nresult = itertools.combinations(data, 3)\n\nfor combo in result:\n    print(combo)<\/code><\/pre>\n\n\n\n
          \u8f93\u51fa\uff1a<\/strong><\/p>\n\n\n\n
          (0, 1, 2)\n(0, 1, 3)\n(0, 1, 4)\n(0, 2, 3)\n(0, 2, 4)\n(0, 3, 4)\n(1, 2, 3)\n(1, 2, 4)\n(1, 3, 4)\n(2, 3, 4)<\/code><\/pre>\n\n\n\n
          \u89e3\u91ca\uff1a<\/p>\n\n\n\n
            \n
          • \u4ece [0, 1, 2, 3, 4]<\/code> \u4e2d\u53d6\u957f\u5ea6\u4e3a 3 \u7684\u7ec4\u5408\uff0c\u5171\u6709 10 \u79cd\u53ef\u80fd\u3002<\/li>\n<\/ul>\n\n\n\n
            \n\n\n\n
            \u6570\u5b66\u516c\u5f0f<\/strong><\/h3>\n\n\n\n
            \u7ec4\u5408\u7684\u603b\u6570\u7531\u516c\u5f0f\u8ba1\u7b97\uff1a
            [
            C(n, r) = \\frac{n!}{r! \\cdot (n – r)!}
            ]<\/p>\n\n\n\n
              \n
            • n<\/code> \u662f iterable<\/code> \u7684\u957f\u5ea6\u3002<\/li>\n\n\n\n
            • r<\/code> \u662f\u9009\u53d6\u7684\u5143\u7d20\u4e2a\u6570\u3002<\/li>\n<\/ul>\n\n\n\n
              \u4f8b\u5982\uff0c\u4e0a\u4f8b\u4e2d\u4ece\u957f\u5ea6\u4e3a 5 \u7684\u96c6\u5408\u4e2d\u53d6 3 \u4e2a\u5143\u7d20\uff1a
              [
              C(5, 3) = \\frac{5!}{3! \\cdot (5-3)!} = 10
              ]<\/p>\n\n\n\n
              \n\n\n\n
              \u6ce8\u610f\u4e8b\u9879<\/strong><\/h3>\n\n\n\n
                \n
              1. \u5982\u679c r<\/code> \u7684\u503c\u5927\u4e8e iterable<\/code> \u7684\u957f\u5ea6\uff0c\u5219\u8fd4\u56de\u7a7a\u8fed\u4ee3\u5668\u3002<\/li>\n<\/ol>\n\n\n\n
                   result = itertools.combinations([1, 2, 3], 4)\n   print(list(result))  # \u8f93\u51fa\uff1a[]<\/code><\/pre>\n\n\n\n
                  \n
                1. \u5982\u679c r<\/code> \u4e3a 0\uff0c\u5219\u8fd4\u56de\u4e00\u4e2a\u7a7a\u5143\u7ec4\uff0c\u8868\u793a\u4ece\u96c6\u5408\u4e2d\u9009\u53d6\u96f6\u4e2a\u5143\u7d20\uff1a<\/li>\n<\/ol>\n\n\n\n
                     result = itertools.combinations([1, 2, 3], 0)\n   print(list(result))  # \u8f93\u51fa\uff1a[()]<\/code><\/pre>\n\n\n\n
                  \n\n\n\n
                  \u4e0e\u6392\u5217\u7684\u533a\u522b<\/strong><\/h3>\n\n\n\n
                    \n
                  • \u7ec4\u5408\uff08combinations<\/code>\uff09\uff1a\u987a\u5e8f\u65e0\u5173\uff0c\u4e0d\u5305\u542b\u91cd\u590d\u3002\u4f8b\u5982\uff0c(1, 2)<\/code> \u548c (2, 1)<\/code> \u662f\u540c\u4e00\u4e2a\u7ec4\u5408\u3002<\/li>\n\n\n\n
                  • \u6392\u5217\uff08permutations<\/code>\uff09\uff1a\u987a\u5e8f\u6709\u5173\uff0c\u6bcf\u79cd\u6392\u5217\u90fd\u4f1a\u5355\u72ec\u8ba1\u7b97\u3002\u4f8b\u5982\uff0c(1, 2)<\/code> \u548c (2, 1)<\/code> \u662f\u4e24\u4e2a\u4e0d\u540c\u7684\u6392\u5217\u3002<\/li>\n<\/ul>\n\n\n\n
                    \n\n\n\n
                    \u603b\u7ed3<\/strong><\/h3>\n\n\n\n
                    itertools.combinations<\/code> \u662f\u751f\u6210\u7ec4\u5408\u7684\u5f3a\u5927\u5de5\u5177\uff0c\u9002\u7528\u4e8e\uff1a<\/p>\n\n\n\n
                      \n
                    • \u89e3\u51b3\u6570\u5b66\u4e2d\u7684\u7ec4\u5408\u95ee\u9898\u3002<\/li>\n\n\n\n
                    • \u7b5b\u9009\u6570\u636e\u7684\u7279\u5b9a\u5b50\u96c6\u3002<\/li>\n\n\n\n
                    • \u751f\u6210\u5404\u79cd\u53ef\u80fd\u7684\u5143\u7d20\u7ec4\uff0c\u9002\u7528\u4e8e\u6982\u7387\u3001\u7edf\u8ba1\u3001\u673a\u5668\u5b66\u4e60\u4e2d\u7684\u7279\u5f81\u7ec4\u5408\u7b49\u573a\u666f\u3002<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"
                      itertools \u662f Python \u7684\u4e00\u4e2a\u6807\u51c6\u5e93\u6a21\u5757\uff0c\u63d0\u4f9b\u4e86\u7528\u4e8e\u64cd\u4f5c\u8fed\u4ee3\u5668\u7684\u51fd\u6570\uff0c\u80fd\u591f\u9ad8\u6548\u5730\u5904\u7406\u5faa\u73af\u548c\u7ec4\u5408\u6570 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1196","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"http:\/\/www.chan.ink\/index.php\/wp-json\/wp\/v2\/posts\/1196","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.chan.ink\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.chan.ink\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.chan.ink\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.chan.ink\/index.php\/wp-json\/wp\/v2\/comments?post=1196"}],"version-history":[{"count":1,"href":"http:\/\/www.chan.ink\/index.php\/wp-json\/wp\/v2\/posts\/1196\/revisions"}],"predecessor-version":[{"id":1197,"href":"http:\/\/www.chan.ink\/index.php\/wp-json\/wp\/v2\/posts\/1196\/revisions\/1197"}],"wp:attachment":[{"href":"http:\/\/www.chan.ink\/index.php\/wp-json\/wp\/v2\/media?parent=1196"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.chan.ink\/index.php\/wp-json\/wp\/v2\/categories?post=1196"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.chan.ink\/index.php\/wp-json\/wp\/v2\/tags?post=1196"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}