{"rsdb":{"rid":"179519","subhead":"","postdate":"0","aid":"130290","fid":"91","uid":"1","topic":"1","content":"
\n
\n \u8bed\u8a00\u7684\u6570\u5b66\u8fd0\u7b97\u548c\u4e00\u4e9b\u7b80\u5355\u7684\u51fd\u6570\u6574\u7406\u5982\u4e0b\uff1a\n <\/div> \n
\n \u5411\u91cf\u53ef\u4ee5\u8fdb\u884c\u90a3\u4e9b\u5e38\u89c4\u7684\u7b97\u672f\u8fd0\u7b97\uff0c\u4e0d\u540c\u957f\u5ea6\u7684\u5411\u91cf\u53ef\u4ee5\u76f8\u52a0\uff0c\u8fd9\u79cd\u60c5\u51b5\u4e0b\u6700\u77ed\u7684\u5411\u91cf\u5c06\u88ab\u5faa\u73af\u4f7f\u7528\u3002\n <\/div> \n
\n  \n <\/div> \n
\n > x <- 1:4\n <\/div> \n
\n > a <- 10\n <\/div> \n
\n > x * a\n <\/div> \n
\n [1] 10 20 30 40\n <\/div> \n
\n  \n <\/div> \n
\n > x + a\n <\/div> \n
\n [1] 11 12 13 14\n <\/div> \n
\n  \n <\/div> \n
\n > sum(x)        #\u5bf9x\u4e2d\u7684\u5143\u7d20\u6c42\u548c\n <\/div> \n
\n [1] 10\n <\/div> \n
\n  \n <\/div> \n
\n > prod(x)       #\u5bf9x\u4e2d\u7684\u5143\u7d20\u6c42\u8fde\u4e58\u79ef\n <\/div> \n
\n [1] 24\n <\/div> \n
\n  \n <\/div> \n
\n > prod(2:8)         #8\u7684\u9636\u4e58\n <\/div> \n
\n [1] 40320\n <\/div> \n
\n  \n <\/div> \n
\n > prod(2:4)         #4\u7684\u9636\u4e58\n <\/div> \n
\n [1] 24\n <\/div> \n
\n  \n <\/div> \n
\n > max(x)            #x\u4e2d\u5143\u7d20\u7684\u6700\u5927\u503c\n <\/div> \n
\n [1] 4\n <\/div> \n
\n  \n <\/div> \n
\n > min(x)            #x\u4e2d\u5143\u7d20\u7684\u6700\u5c0f\u503c\n <\/div> \n
\n [1] 1\n <\/div> \n
\n  \n <\/div> \n
\n > which.max(x)      #\u8fd4\u56dex\u4e2d\u6700\u5927\u5143\u7d20\u7684\u4e0b\u6807\n <\/div> \n
\n [1] 4\n <\/div> \n
\n  \n <\/div> \n
\n > which.min(x)      #\u8fd4\u56dex\u4e2d\u6700\u5c0f\u5143\u7d20\u7684\u4e0b\u6807\n <\/div> \n
\n [1] 1\n <\/div> \n
\n  \n <\/div> \n
\n > x <- 4:1          #\u5bf9\u5411\u91cfx\u91cd\u65b0\u8d4b\u503c\n <\/div> \n
\n > x\n <\/div> \n
\n [1] 4 3 2 1\n <\/div> \n
\n  \n <\/div> \n
\n > which.min(x)\n <\/div> \n
\n [1] 4\n <\/div> \n
\n  \n <\/div> \n
\n > which.max(x)\n <\/div> \n
\n [1] 1\n <\/div> \n
\n  \n <\/div> \n
\n > range(x)           #\u4e0ec(min(x), max(x))\u4f5c\u7528\u76f8\u540c\n <\/div> \n
\n [1] 1 4\n <\/div> \n
\n  \n <\/div> \n
\n > mean(x)            #x\u4e2d\u5143\u7d20\u7684\u5747\u503c\n <\/div> \n
\n [1] 2.5\n <\/div> \n
\n  \n <\/div> \n
\n > median(x)          #x\u4e2d\u5143\u7d20\u7684\u4e2d\u4f4d\u6570\n <\/div> \n
\n [1] 2.5\n <\/div> \n
\n  \n <\/div> \n
\n > var(x)         #x\u4e2d\u5143\u7d20\u7684\u7684\u65b9\u5dee\uff08\u7528n-1\u505a\u5206\u6bcd\uff09\n <\/div> \n
\n [1] 1.666667\n <\/div> \n
\n  \n <\/div> \n
\n > x\n <\/div> \n
\n [1] 4 3 2 1\n <\/div> \n
\n  \n <\/div> \n
\n > rev(x)         #\u5bf9x\u4e2d\u7684\u5143\u7d20\u53d6\u9006\u5e8f\n <\/div> \n
\n [1] 1 2 3 4\n <\/div> \n
\n  \n <\/div> \n
\n > sort(x)        #\u5c06x\u4e2d\u7684\u5143\u7d20\u6309\u5347\u5e8f\u6392\u5217\uff1b\n <\/div> \n
\n [1] 1 2 3 4\n <\/div> \n
\n  \n <\/div> \n
\n > x\n <\/div> \n
\n [1] 4 3 2 1\n <\/div> \n
\n  \n <\/div> \n
\n > cumsum(x)      #\u6c42\u7d2f\u79ef\u548c\uff0c\u8fd4\u56de\u4e00\u4e2a\u5411\u91cf\uff0c\u5b83\u7684\u7b2ci\u4e2a\u5143\u7d20\u662f\u4ecex[1]\u5230x[i]\u7684\u548c\n <\/div> \n
\n [1] 4  7  9 10\n <\/div> \n
\n  \n <\/div> \n
\n > cumsum(rev(x))\n <\/div> \n
\n [1] 1  3  6 10\n <\/div> \n
\n  \n <\/div> \n
\n > y <- 11:14\n <\/div> \n
\n > pmin(x,y)      #\u8fd4\u56de\u4e00\u4e2a\u5411\u91cf\uff0c\u5b83\u7684\u7b2ci\u4e2a\u5143\u7d20\u662fx[i], y[i], . . .\u4e2d\u6700\u5c0f\u503c\n <\/div> \n
\n [1] 4 3 2 1\n <\/div> \n
\n  \n <\/div> \n
\n > x <- rev(x) #\u91cd\u65b0\u8d4b\u503c\n <\/div> \n
\n > pmin(x,y)\n <\/div> \n
\n [1] 1 2 3 4\n <\/div> \n
\n  \n <\/div> \n
\n > pmax(x,y)   #\u8fd4\u56de\u4e00\u4e2a\u5411\u91cf\uff0c\u5b83\u7684\u6bcf\u4e2a\u5143\u7d20\u662f\u5411\u91cfx\u548cy\u5728\u76f8\u5e94\u4f4d\u7f6e\u7684\u5143\u7d20\u7684\u6700\u5927\u8005\n <\/div> \n
\n [1] 11 12 13 14\n <\/div> \n
\n  \n <\/div> \n
\n > cumprod(x) #\u6c42\u7d2f\u79ef\uff08\u4ece\u5de6\u5411\u53f3\uff09\u4e58\u79ef\n <\/div> \n
\n [1] 1  2  6 24\n <\/div> \n
\n  \n <\/div> \n
\n > cummin(x)  #\u6c42\u7d2f\u79ef\u6700\u5c0f\u503c\uff08\u4ece\u5de6\u5411\u53f3\uff09\n <\/div> \n
\n [1] 1 1 1 1\n <\/div> \n
\n  \n <\/div> \n
\n > cummax(x)  #\u6c42\u7d2f\u79ef\u6700\u5927\u503c\uff08\u4ece\u5de6\u5411\u53f3\uff09\n <\/div> \n
\n [1] 1 2 3 4\n <\/div> \n
\n  \n <\/div> \n
\n > match(x, y)  #\u8fd4\u56de\u4e00\u4e2a\u548cx\u7684\u957f\u5ea6\u76f8\u540c\u7684\u5411\u91cf\uff0c\u8868\u793ax\u4e2d\u4e0ey\u4e2d\u5143\u7d20\u76f8\u540c\u7684\u5143\u7d20\u5728y\u4e2d\u7684\u4f4d\u7f6e\uff08\u6ca1\u6709\u5219\u8fd4\u56deNA\uff09\n <\/div> \n
\n [1] NA NA NA NA\n <\/div> \n
\n  \n <\/div> \n
\n > y[c(2,4)] <- c(2,4)\n <\/div> \n
\n > y\n <\/div> \n
\n [1] 11 2 13  4\n <\/div> \n
\n  \n <\/div> \n
\n > match(x, y)\n <\/div> \n
\n [1] NA 2   NA  4\n <\/div> \n
\n  \n <\/div> \n
\n na.omit(x)\u51fd\u6570\u5ffd\u7565\u6709\u7f3a\u5931\u503c\uff08NA\uff09\u7684\u89c2\u5bdf\u6570\u636e\uff08\u5982\u679cx\u662f\u77e9\u9635\u6216\u6570\u636e\u6846\u5219\u5ffd\u7565\u76f8\u5e94\u7684\u884c\uff09\n <\/div> \n
\n > na.omit(match(x,y))\n <\/div> \n
\n [1] 2 4\n <\/div> \n
\n  \n <\/div> \n
\n attr(,"na.action")\n <\/div> \n
\n [1] 1 3\n <\/div> \n
\n  \n <\/div> \n
\n attr(,"class")\n <\/div> \n
\n [1] "omit"\n <\/div> \n
\n  \n <\/div> \n
\n > na.fail(match(x,y)) #na.fail(x) \u5982\u679cx\u5305\u542b\u81f3\u5c11\u4e00\u4e2aNA\u5219\u8fd4\u56de\u4e00\u4e2a\u9519\u8bef\u6d88\u606f\n <\/div> \n
\n \u9519\u8bef\u4e8ena.fail.default(match(x,y)) : \u5bf9\u8c61\u91cc\u6709\u907a\u6f0f\u503c\n <\/div> \n
\n  \n <\/div> \n
\n which\uff08\uff09\u51fd\u6570\u8fd4\u56de\u4e00\u4e2a\u5305\u542bx\u7b26\u5408\u6761\u4ef6\uff08\u5f53\u6bd4\u8f83\u8fd0\u7b97\u7ed3\u679c\u4e3a\u771f\uff08TRUE\uff09\u7684\u4e0b\u6807\u7684\u5411\u91cf\uff0c\u5728\u8fd9\u4e2a\u7ed3\u679c\u5411\u91cf\u4e2d\u6570\u503ci\u8bf4\u660ex[i] == a\uff08\u8fd9\u4e2a\u51fd\u6570\u7684\u53c2\u6570\u5fc5\u987b\u662f\u903b\u8f91\u578b\u53d8\u91cf\uff09\n <\/div> \n
\n > which( x == 2)\n <\/div> \n
\n [1] 2\n <\/div> \n
\n  \n <\/div> \n
\n > which( x <= 2)\n <\/div> \n
\n [1] 1 2\n <\/div> \n
\n  \n <\/div> \n
\n \u6c42\u7ec4\u5408\u6570\n <\/div> \n
\n > choose(4,2)\n <\/div> \n
\n [1] 6\n <\/div> \n
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