{"id":278,"date":"2017-02-07T13:38:59","date_gmt":"2017-02-07T05:38:59","guid":{"rendered":"http:\/\/luchanglong.com.cn\/?p=278"},"modified":"2017-02-07T13:38:59","modified_gmt":"2017-02-07T05:38:59","slug":"python-%e5%b8%b8%e7%94%a8%e5%86%85%e5%bb%ba%e6%a8%a1%e5%9d%97-collections","status":"publish","type":"post","link":"https:\/\/blog.la998.com\/?p=278","title":{"rendered":"python \u5e38\u7528\u5185\u5efa\u6a21\u5757-collections"},"content":{"rendered":"

namedtuple<\/h3>\n

\u6211\u4eec\u77e5\u9053tuple<\/code>\u53ef\u4ee5\u8868\u793a\u4e0d\u53d8\u96c6\u5408\uff0c\u4f8b\u5982\uff0c\u4e00\u4e2a\u70b9\u7684\u4e8c\u7ef4\u5750\u6807\u5c31\u53ef\u4ee5\u8868\u793a\u6210\uff1a<\/p>\n

>>> <\/span>p = (1<\/span>, 2<\/span>)\r\n<\/code><\/pre>\n
\u4f46\u662f\uff0c\u770b\u5230(1, 2)<\/code>\uff0c\u5f88\u96be\u770b\u51fa\u8fd9\u4e2atuple<\/code>\u662f\u7528\u6765\u8868\u793a\u4e00\u4e2a\u5750\u6807\u7684\u3002<\/p>\n
\u5b9a\u4e49\u4e00\u4e2aclass\u53c8\u5c0f\u9898\u5927\u505a\u4e86\uff0c\u8fd9\u65f6\uff0cnamedtuple<\/code>\u5c31\u6d3e\u4e0a\u4e86\u7528\u573a\uff1a<\/p>\n
>>> <\/span>from<\/span> collections import<\/span> namedtuple\r\n>>> <\/span>Point = namedtuple('Point'<\/span>, ['x'<\/span>, 'y'<\/span>])\r\n>>> <\/span>p = Point(1<\/span>, 2<\/span>)\r\n>>> <\/span>p.x\r\n1<\/span>\r\n>>> <\/span>p.y\r\n2<\/span>\r\n<\/code><\/pre>\n
namedtuple<\/code>\u662f\u4e00\u4e2a\u51fd\u6570\uff0c\u5b83\u7528\u6765\u521b\u5efa\u4e00\u4e2a\u81ea\u5b9a\u4e49\u7684tuple<\/code>\u5bf9\u8c61\uff0c\u5e76\u4e14\u89c4\u5b9a\u4e86tuple<\/code>\u5143\u7d20\u7684\u4e2a\u6570\uff0c\u5e76\u53ef\u4ee5\u7528\u5c5e\u6027\u800c\u4e0d\u662f\u7d22\u5f15\u6765\u5f15\u7528tuple<\/code>\u7684\u67d0\u4e2a\u5143\u7d20\u3002<\/p>\n
\u8fd9\u6837\u4e00\u6765\uff0c\u6211\u4eec\u7528namedtuple<\/code>\u53ef\u4ee5\u5f88\u65b9\u4fbf\u5730\u5b9a\u4e49\u4e00\u79cd\u6570\u636e\u7c7b\u578b\uff0c\u5b83\u5177\u5907tuple\u7684\u4e0d\u53d8\u6027\uff0c\u53c8\u53ef\u4ee5\u6839\u636e\u5c5e\u6027\u6765\u5f15\u7528\uff0c\u4f7f\u7528\u5341\u5206\u65b9\u4fbf\u3002<\/p>\n
\u53ef\u4ee5\u9a8c\u8bc1\u521b\u5efa\u7684Point<\/code>\u5bf9\u8c61\u662ftuple<\/code>\u7684\u4e00\u79cd\u5b50\u7c7b\uff1a<\/p>\n
>>> <\/span>isinstance(p, Point)\r\nTrue<\/span>\r\n>>> <\/span>isinstance(p, tuple)\r\nTrue<\/span>\r\n<\/code><\/pre>\n
\u7c7b\u4f3c\u7684\uff0c\u5982\u679c\u8981\u7528\u5750\u6807\u548c\u534a\u5f84\u8868\u793a\u4e00\u4e2a\u5706\uff0c\u4e5f\u53ef\u4ee5\u7528namedtuple<\/code>\u5b9a\u4e49\uff1a<\/p>\n
# namedtuple('\u540d\u79f0', [\u5c5e\u6027list]):<\/span>\r\nCircle<\/span> = namedtuple('Circle'<\/span>, ['x'<\/span>, 'y'<\/span>, 'r'<\/span>])<\/code><\/pre>\n
 <\/p>\n
deque<\/h3>\n
\u4f7f\u7528list<\/code>\u5b58\u50a8\u6570\u636e\u65f6\uff0c\u6309\u7d22\u5f15\u8bbf\u95ee\u5143\u7d20\u5f88\u5feb\uff0c\u4f46\u662f\u63d2\u5165\u548c\u5220\u9664\u5143\u7d20\u5c31\u5f88\u6162\u4e86\uff0c\u56e0\u4e3alist<\/code>\u662f\u7ebf\u6027\u5b58\u50a8\uff0c\u6570\u636e\u91cf\u5927\u7684\u65f6\u5019\uff0c\u63d2\u5165\u548c\u5220\u9664\u6548\u7387\u5f88\u4f4e\u3002<\/p>\n
deque\u662f\u4e3a\u4e86\u9ad8\u6548\u5b9e\u73b0\u63d2\u5165\u548c\u5220\u9664\u64cd\u4f5c\u7684\u53cc\u5411\u5217\u8868\uff0c\u9002\u5408\u7528\u4e8e\u961f\u5217\u548c\u6808\uff1a<\/p>\n
>>> <\/span>from<\/span> collections import<\/span> deque\r\n>>> <\/span>q = deque(['a'<\/span>, 'b'<\/span>, 'c'<\/span>])\r\n>>> <\/span>q.append('x'<\/span>)\r\n>>> <\/span>q.appendleft('y'<\/span>)\r\n>>> <\/span>q\r\ndeque(['y'<\/span>, 'a'<\/span>, 'b'<\/span>, 'c'<\/span>, 'x'<\/span>])\r\n<\/code><\/pre>\n
deque<\/code>\u9664\u4e86\u5b9e\u73b0list\u7684append()<\/code>\u548cpop()<\/code>\u5916\uff0c\u8fd8\u652f\u6301appendleft()<\/code>\u548cpopleft()<\/code>\uff0c\u8fd9\u6837\u5c31\u53ef\u4ee5\u975e\u5e38\u9ad8\u6548\u5730\u5f80\u5934\u90e8\u6dfb\u52a0\u6216\u5220\u9664\u5143\u7d20\u3002<\/p>\n
 <\/p>\n
defaultdict<\/h3>\n
\u4f7f\u7528dict<\/code>\u65f6\uff0c\u5982\u679c\u5f15\u7528\u7684Key\u4e0d\u5b58\u5728\uff0c\u5c31\u4f1a\u629b\u51faKeyError<\/code>\u3002\u5982\u679c\u5e0c\u671bkey\u4e0d\u5b58\u5728\u65f6\uff0c\u8fd4\u56de\u4e00\u4e2a\u9ed8\u8ba4\u503c\uff0c\u5c31\u53ef\u4ee5\u7528defaultdict<\/code>\uff1a<\/p>\n
>>> <\/span>from<\/span> collections import<\/span> defaultdict\r\n>>> <\/span>dd = defaultdict(lambda<\/span>: 'N\/A'<\/span>)\r\n>>> <\/span>dd['key1'<\/span>] = 'abc'<\/span>\r\n>>> <\/span>dd['key1'<\/span>] # key1\u5b58\u5728<\/span>\r\n'abc'<\/span>\r\n>>> <\/span>dd['key2'<\/span>] # key2\u4e0d\u5b58\u5728\uff0c\u8fd4\u56de\u9ed8\u8ba4\u503c<\/span>\r\n'N\/A'<\/span>\r\n<\/code><\/pre>\n
\u6ce8\u610f\u9ed8\u8ba4\u503c\u662f\u8c03\u7528\u51fd\u6570\u8fd4\u56de\u7684\uff0c\u800c\u51fd\u6570\u5728\u521b\u5efadefaultdict<\/code>\u5bf9\u8c61\u65f6\u4f20\u5165\u3002<\/p>\n
\u9664\u4e86\u5728Key\u4e0d\u5b58\u5728\u65f6\u8fd4\u56de\u9ed8\u8ba4\u503c\uff0cdefaultdict<\/code>\u7684\u5176\u4ed6\u884c\u4e3a\u8ddfdict<\/code>\u662f\u5b8c\u5168\u4e00\u6837\u7684\u3002<\/p>\n
OrderedDict<\/h3>\n
\u4f7f\u7528dict<\/code>\u65f6\uff0cKey\u662f\u65e0\u5e8f\u7684\u3002\u5728\u5bf9dict<\/code>\u505a\u8fed\u4ee3\u65f6\uff0c\u6211\u4eec\u65e0\u6cd5\u786e\u5b9aKey\u7684\u987a\u5e8f\u3002<\/p>\n
\u5982\u679c\u8981\u4fdd\u6301Key\u7684\u987a\u5e8f\uff0c\u53ef\u4ee5\u7528OrderedDict<\/code>\uff1a<\/p>\n
>>> <\/span>from<\/span> collections import<\/span> OrderedDict\r\n>>> <\/span>d = dict([('a'<\/span>, 1<\/span>), ('b'<\/span>, 2<\/span>), ('c'<\/span>, 3<\/span>)])\r\n>>> <\/span>d # dict\u7684Key\u662f\u65e0\u5e8f\u7684<\/span>\r\n{'a'<\/span>: 1<\/span>, 'c'<\/span>: 3<\/span>, 'b'<\/span>: 2<\/span>}\r\n>>> <\/span>od = OrderedDict([('a'<\/span>, 1<\/span>), ('b'<\/span>, 2<\/span>), ('c'<\/span>, 3<\/span>)])\r\n>>> <\/span>od # OrderedDict\u7684Key\u662f\u6709\u5e8f\u7684<\/span>\r\nOrderedDict([('a'<\/span>, 1<\/span>), ('b'<\/span>, 2<\/span>), ('c'<\/span>, 3<\/span>)])\r\n<\/code><\/pre>\n
\u6ce8\u610f\uff0cOrderedDict<\/code>\u7684Key\u4f1a\u6309\u7167\u63d2\u5165\u7684\u987a\u5e8f\u6392\u5217\uff0c\u4e0d\u662fKey\u672c\u8eab\u6392\u5e8f\uff1a<\/p>\n
>>> <\/span>od = OrderedDict()\r\n>>> <\/span>od['z'<\/span>] = 1<\/span>\r\n>>> <\/span>od['y'<\/span>] = 2<\/span>\r\n>>> <\/span>od['x'<\/span>] = 3<\/span>\r\n>>> <\/span>list(od.keys()) # \u6309\u7167\u63d2\u5165\u7684Key\u7684\u987a\u5e8f\u8fd4\u56de<\/span>\r\n['z'<\/span>, 'y'<\/span>, 'x'<\/span>]\r\n<\/code><\/pre>\n
OrderedDict<\/code>\u53ef\u4ee5\u5b9e\u73b0\u4e00\u4e2aFIFO\uff08\u5148\u8fdb\u5148\u51fa\uff09\u7684dict\uff0c\u5f53\u5bb9\u91cf\u8d85\u51fa\u9650\u5236\u65f6\uff0c\u5148\u5220\u9664\u6700\u65e9\u6dfb\u52a0\u7684Key<\/p>\n
Counter<\/h3>\n
Counter<\/code>\u662f\u4e00\u4e2a\u7b80\u5355\u7684\u8ba1\u6570\u5668\uff0c\u4f8b\u5982\uff0c\u7edf\u8ba1\u5b57\u7b26\u51fa\u73b0\u7684\u4e2a\u6570\uff1a<\/p>\n
>>> <\/span>from<\/span> collections import<\/span> Counter\r\n>>> <\/span>c = Counter()\r\n>>> <\/span>for<\/span> ch in<\/span> 'programming'<\/span>:\r\n... <\/span>    c[ch] = c[ch] + 1<\/span>\r\n...\r\n>>> <\/span>c\r\nCounter({'g'<\/span>: 2<\/span>, 'm'<\/span>: 2<\/span>, 'r'<\/span>: 2<\/span>, 'a'<\/span>: 1<\/span>, 'i'<\/span>: 1<\/span>, 'o'<\/span>: 1<\/span>, 'n'<\/span>: 1<\/span>, 'p'<\/span>: 1<\/span>})\r\n<\/code><\/pre>\n
Counter<\/code>\u5b9e\u9645\u4e0a\u4e5f\u662fdict<\/code>\u7684\u4e00\u4e2a\u5b50\u7c7b\uff0c\u4e0a\u9762\u7684\u7ed3\u679c\u53ef\u4ee5\u770b\u51fa\uff0c\u5b57\u7b26'g'<\/code>\u3001'm'<\/code>\u3001'r'<\/code>\u5404\u51fa\u73b0\u4e86\u4e24\u6b21\uff0c\u5176\u4ed6\u5b57\u7b26\u5404\u51fa\u73b0\u4e86\u4e00\u6b21\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
namedtuple \u6211\u4eec\u77e5\u9053tuple\u53ef\u4ee5\u8868\u793a\u4e0d\u53d8\u96c6\u5408\uff0c\u4f8b\u5982\uff0c\u4e00\u4e2a\u70b9\u7684\u4e8c\u7ef4\u5750\u6807\u5c31\u53ef\u4ee5\u8868\u793a\u6210\uff1a >&gt … \u7ee7\u7eed\u9605\u8bfbpython \u5e38\u7528\u5185\u5efa\u6a21\u5757-collections<\/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":[10],"tags":[],"class_list":["post-278","post","type-post","status-publish","format-standard","hentry","category-python"],"_links":{"self":[{"href":"https:\/\/blog.la998.com\/index.php?rest_route=\/wp\/v2\/posts\/278","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.la998.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.la998.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.la998.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.la998.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=278"}],"version-history":[{"count":1,"href":"https:\/\/blog.la998.com\/index.php?rest_route=\/wp\/v2\/posts\/278\/revisions"}],"predecessor-version":[{"id":279,"href":"https:\/\/blog.la998.com\/index.php?rest_route=\/wp\/v2\/posts\/278\/revisions\/279"}],"wp:attachment":[{"href":"https:\/\/blog.la998.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=278"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.la998.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=278"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.la998.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=278"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}