{"rsdb":{"rid":"345979","subhead":"","postdate":"0","aid":"246456","fid":"91","uid":"1","topic":"1","content":"
\n

fread\u4e2dnThread \u53c2\u6570\u7684\u4f7f\u7528<\/h3> \n

??\u6ce8\u610f\u9ed8\u8ba4nThread=getDTthreads()\uff0c\u5373\u4f7f\u7528\u6240\u6709\u80fd\u7528\u7684\u6838\u5fc3\uff0c\u4f46\u5e76\u4e0d\u662f\u6838\u5fc3\u7528\u7684\u8d8a\u591a\u8d8a\u597d\uff0c\u672c\u4eba\u4eb2\u81ea\u6d4b\u8bd5\u7684\u60c5\u51b5\u4e0b\uff0c\u5176\u5b9e\u5355\u6838\u5177\u6709\u8f83\u5f3a\u7684\u6027\u80fd\uff0c\u53ea\u6709\u5728\u6570\u636e\u5927\u4e8e3Gb\u7684\u60c5\u51b5\u4e0b\uff0c\u5f00\u542f11\u6838\uff08\u6211\u7684\u673a\u5668\u5168\u90e8\u6838\u5fc330\u591a\u6838\uff09\u6548\u7387\u624d\u6bd4\u4e00\u4e2a\u6838\u5fc3\u66f4\u9ad8\uff0c\u800c\u9ed8\u8ba4\u4f7f\u7528\u5168\u90e8\u7684\u6838\u5fc3\u6548\u7387\u4e00\u76f4\u975e\u5e38\u4f4e\u3002\u56e0\u6b64\u5bf9\u4e8e\u4e0d\u662f\u975e\u5e38\u5de8\u5927\u7684\u6587\u4ef6\uff0c\u5efa\u8bae\u8bbe\u7f6e\u4e3a1\uff0c\u4e0d\u8981\u4f7f\u7528\u5168\u90e8\u6838\u5fc3<\/p> \n

fread\u4e2dsep\u662f\u81ea\u52a8\u68c0\u6d4b\u7684<\/h3> \n

??\u6240\u4ee5\u5728\u5faa\u73af\u8bfb\u5165\u6587\u4ef6\u7684\u8fc7\u7a0b\u4e2d\uff0c\u5c31\u7b97\u4e0d\u540c\u6587\u4ef6\u7684\u5206\u9694\u7b26\u4e0d\u540c\uff0c\u4e5f\u53ef\u4ee5\u5faa\u73af\u4e00\u6b21\u6027\u65b9\u4fbf\u7684\u8bfb\u5165\uff1b \u8fd8\u6709\u5c31\u7b97\u540e\u7eed\u6539\u53d8\u4e86\u6587\u4ef6\u7684\u5206\u9694\u7b26\uff0c\u6587\u4ef6\u4e5f\u53ef\u4ee5\u8bfb\u5165\uff0c\u5efa\u8bae\u4e0d\u52a0\u5206\u9694\u7b26<\/p> \n

fread\u53ef\u4ee5\u81ea\u52a8\u68c0\u6d4b\u6ce8\u91ca\uff0c\u5e76\u4e14\u8df3\u8fc7\u6ce8\u91ca\u884c<\/h3> \n

??\u9ed8\u8ba4skip=0\uff0c\u4f1a\u8df3\u8fc7\u4e0d\u89c4\u5219\u7684\u884c\uff0c\u56e0\u6b64\u6709\u6ce8\u91ca\u884c\u65f6\uff0c\u53ef\u4ee5\u8d70\u9ed8\u8ba4\u7684skip\u53c2\u6570<\/p> \n

\u8f6c\u6362\u6210\u77e9\u9635\u65f6\u53ef\u4ee5\u4fdd\u7559\u67d0\u4e00\u5217\u4e3arowname<\/h3> \n

??as.matrix\u4f5c\u7528\u4e8edata.table\u65f6\u4f1a\u8c03\u7528as.matrix.data.table\uff0c\u6709\u4e00\u4e2arownames\u53c2\u6570\u53ef\u4ee5\u6307\u5b9a\u4fdd\u7559\u4e3a\u884c\u540d\u7684\u5217<\/p> \n

\u77e9\u9635\u8f6c\u6362\u6210data.table\u65f6\u53ef\u4ee5\u4fdd\u7559\u5217\u540d<\/h3> \n

??\u5728as.data.table\u51fd\u6570\u4e2d\u540c\u6837\u6709\u4e00\u4e2arownames\u53c2\u6570\uff0c\u8bbe\u7f6e\u4e3aT\u53ef\u4ee5\u5c06\u884c\u540d\u4fdd\u7559\u4e0b\u6765\u4f5c\u4e3adata.table\u7684\u4e00\u5217<\/p> \n

\u4e0d\u5efa\u8baeset\u548cfor\u5faa\u73af\u4e00\u8d77\u4f7f\u7528<\/h3> \n

??\u867d\u7136set\u53ef\u4ee5\u5728\u5185\u5b58\u4e0a\u76f4\u63a5\u6539\u53d8\u6570\u503c\uff0c\u4f46\u5728R\u4e2d\u7528for\u5faa\u73af\u6bd4\u6279\u91cf\u5217\u8fd0\u7b97\u6162\u7684\u591a\uff0c\u56e0\u6b64\u9996\u9009:=\u6216\u8005apply\u7b49<\/p> \n

\u5728\u5904\u7406\u6d6e\u70b9\u6570\u65f6\u4f1a\u6709\u4e00\u4e9b\u51c6\u786e\u6027\u7684\u95ee\u9898<\/h3> \n

??\u6bd4\u5982\u7528seq\u51fd\u6570numeric\u7c7b\u578b\u7684\u6570\u503c\u65f6\uff0c\u4f1a\u5b58\u5728\u4e0d\u51c6\u786e\u7684\u95ee\u9898\uff0c\u6bd4\u5982seq(0,1,by=0.2)\u4e2d\u76840.6\u5c31\u4e0d\u7b49\u4e8e0.6\uff0c \u867d\u7136\u5f88\u8d39\u89e3\uff0c\u4f46\u8fd9\u662f\u56e0\u4e3a\u8ba1\u7b97\u673a\u5728\u5b58\u50a8\u6d6e\u70b9\u6570\u65f6\u51fa\u73b0\u7684\u4e00\u4e9b\u95ee\u9898\u3002\u73b0\u5728\u53ea\u53d1\u73b0seq\u51fd\u6570\u4f1a\u51fa\u73b0\u8fd9\u79cd\u60c5\u51b5\uff0cmanual\u4e2d\u63d0\u4f9b\u4e86\u4e00\u4e2a\u51fd\u6570\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\uff0csetNumericRounding(2) \uff0c\u53bb\u9664\u6700\u540e\u4e24\u4e2a\u5b57\u8282\uff0c\u8fd9\u6837\u8fd0\u884c\u7684\u66f4\u5feb\uff0c\u4e5f\u4e0d\u4f1a\u51fa\u73b00.6\u4e0d\u7b49\u4e8e0.6\u7684\u95ee\u9898<\/p> \n

\u652f\u6301\u6570\u636e\u6846\u53d6\u4ea4\u96c6\u548c\u5e76\u96c6<\/h3> \n

??\u7c7b\u4f3c\u4e8e\u96c6\u5408\u8fd0\u7b97\uff0cdata.table\u4e2dfintersect, fsetdiff, funion\uff0cfsetequal\u51fd\u6570\u80fd\u5bf9\u4e0d\u540c\u6570\u636e\u6846\u7684\u884c\u6c42\u4ea4\u96c6\uff0c\u5dee\u96c6\uff0c\u5e76\u96c6\u7b49<\/p> \n

\u53ef\u4ee5\u76f4\u63a5\u5bf9\u5217\u6309\u5206\u9694\u7b26\u8fdb\u884c\u5206\u5272<\/h3> \n

??\u5e94\u7528tstrsplit\u51fd\u6570\u53ef\u4ee5\u5c06\u4e00\u5217\u6309\u7167\u5206\u9694\u7b26\u5206\u6210\u591a\u5217\uff0c\u51fd\u6570\u8fd4\u56de\u7684\u662f\u4e00\u4e2a\u5217\u8868\uff0c\u4e3e\u4f8b\uff1aDT[, c("c1", "c2") := tstrsplit(x, "\/", fixed=TRUE)][]\uff0c\u5c06x\u5217\u6309\u7167\/\u5206\u9694\uff0c\u5206\u5272\u6210c1\uff0cc2\u4e24\u5217<\/p> \n

\u652f\u6301\u7c7b\u4f3c\u4e8eSQLs\u7684\u5206\u7ec4\u8fd0\u7b97<\/h3> \n

??\u5e26\u6709rollup\uff0c cube\uff0c groupingsets\u51fd\u6570<\/p> \n

\u53c2\u8003\u8d44\u6599<\/h3> \n

data.table 1.11.2 manual\uff1ahttps:\/\/cran.r-project.org\/web\/packages\/data.table\/data.table.pdf<\/a><\/p> \n<\/div>","orderid":"0","title":"data.table\u5305\u4f7f\u7528\u5e94\u8be5\u6ce8\u610f\u7684\u4e00\u4e9b\u7ec6\u8282","smalltitle":"","mid":"0","fname":"R\u8bed\u8a00","special_id":"0","bak_id":"0","info":"0","hits":"240","pages":"1","comments":"0","posttime":"2019-09-03 02:41:24","list":"1567449684","username":"admin","author":"","copyfrom":"","copyfromurl":"","titlecolor":"","fonttype":"0","titleicon":"0","picurl":"https:\/\/www.cppentry.com\/upload_files\/","ispic":"0","yz":"1","yzer":"","yztime":"0","levels":"0","levelstime":"0","keywords":"data.table<\/A> \u4f7f\u7528<\/A> \u5e94\u8be5<\/A> \u6ce8\u610f<\/A> \u4e00\u4e9b<\/A> \u7ec6\u8282<\/A>","jumpurl":"","iframeurl":"","style":"","template":"a:3:{s:4:\"head\";s:0:\"\";s:4:\"foot\";s:0:\"\";s:8:\"bencandy\";s:0:\"\";}","target":"0","ip":"120.229.33.54","lastfid":"0","money":"0","buyuser":"","passwd":"","allowdown":"","allowview":"","editer":"","edittime":"0","begintime":"0","endtime":"0","description":"data.table\u5305\u4f7f\u7528\u5e94\u8be5\u6ce8\u610f\u7684\u4e00\u4e9b\u7ec6\u8282","lastview":"1713849187","digg_num":"0","digg_time":"0","forbidcomment":"0","ifvote":"0","heart":"","htmlname":"","city_id":"0"},"page":"1"}