{"id":1035,"date":"2019-03-17T23:07:35","date_gmt":"2019-03-17T14:07:35","guid":{"rendered":"http:\/\/141.164.34.82\/?p=1035"},"modified":"2019-03-17T23:18:08","modified_gmt":"2019-03-17T14:18:08","slug":"dplyr%ec%9d%84-data-table%eb%a1%9c-%eb%b2%88%ec%97%ad%ed%95%98%ea%b8%b0","status":"publish","type":"post","link":"http:\/\/ds.sumeun.org\/?p=1035","title":{"rendered":"dplyr\uc744 data.table\ub85c \ubc88\uc5ed\ud558\uae30"},"content":{"rendered":"<h1>\ud328\ud0a4\uc9c0 \ub370\uc774\ud130\ud14c\uc774\ube14(<code>data.table<\/code>)<\/h1>\n<h2><code>package:dplyr<\/code>\uacfc <code>package:data.table<\/code>\uc758 \ube44\uad50<\/h2>\n<ul>\n<li><code>package:data.table<\/code>\ub294 \ub300\uc6a9\ub7c9\uc758 \ub370\uc774\ud130\ub97c \ubd84\uc0b0 \ucc98\ub9ac \uc2dc\uc2a4\ud15c\uc758 \ub3c4\uc6c0\uc5c6\uc774 \ucc98\ub9ac\ud560 \uc218 \uc788\ub294 \ucd5c\uc120\uc758 \ubc29\ubc95\uc774\ub2e4. \uc5ec\ub7ec \ubca4\uce58\ub9c8\ud0b9 \uacb0\uacfc\ub294 \ub370\uc774\ud130\ud14c\uc774\ube14(<code>data.table<\/code>)\uc774 \ube45\ub370\uc774\ud130\ub97c \ucc98\ub9ac\ud558\ub294\ub370 \ud0c0\uc758 \ucd94\uc885\uc744 \ubd88\ud5c8\ud568\uc744 \ubcf4\uc5ec\uc8fc\uc5c8\ub2e4. \uadf8\ub7ec\ub098 \uc804\ud1b5\uc801\uc778 R\uc758 \ubb38\ubc95\uacfc \uc0c1\uc774\ud558\uace0, \ub2e4\uc18c \ub09c\ud574\ud55c \ubb38\ubc95 \ub54c\ubb38\uc5d0 \ub110\ub9ac \uc0ac\uc6a9\ub418\uc9c0 \ubabb\ud558\ub294 \ub4ef \ud558\ub2e4.<\/li>\n<li>\uc5ec\uae30\uc11c\ub294 \uc77d\uae30 \uc26c\uc6b4 <code>package:dplyr<\/code>\uc758 \uc5ec\ub7ec \ud568\uc218(<code>slice<\/code>, <code>filter<\/code> \ub4f1)\uc744 <code>package:data.table<\/code>\ub85c \ubc88\uc5ed\ud558\uc5ec, \ub370\uc774\ud130\ud14c\uc774\ube14\uc758 \uc811\uadfc\uc131\uc744 \ub192\uc774\ub824 \ud558\uc600\ub2e4.<\/li>\n<li>\ud568\uc218 \ubc88\uc5ed \uc21c\uc11c\ub294 \uc77c\ubc18\uc801\uc778 <code>package:dplyr<\/code>\uc758 \uc791\uc5c5 \uc21c\uc11c\ub85c \ub2e4\uc74c\uacfc \uac19\ub2e4.<\/li>\n<\/ul>\n<p><code>slice<\/code>&#8211;<code>select<\/code>&#8211;<code>filter<\/code>&#8211;<code>mutate<\/code>\/<code>transmute<\/code>&#8211;<code>group_by<\/code>&#8211;<code>summarise<\/code>&#8211;<code>arrange(,by_group=T)<\/code><\/p>\n<h3>\ubaa9\ucc28<\/h3>\n<ul>\n<li><a href=\"#slice\"><code>slice<\/code><\/a><\/li>\n<li><a href=\"#select\"><code>select<\/code><\/a><\/li>\n<li><a href=\"#filter\"><code>filter<\/code><\/a><\/li>\n<li><a href=\"#mutate\"><code>mutate<\/code><\/a><\/li>\n<li><a href=\"#transmute\"><code>transmute<\/code><\/a><\/li>\n<li><a href=\"#arrange\"><code>arrange<\/code><\/a> : <code>DT[order(cola)]<\/code><\/li>\n<li><a href=\"#groupby\"><code>group_by<\/code><\/a> : <code>DT[i, j, by]<\/code><\/li>\n<li><a href=\"#summary\">\uc885\ud569<\/a><\/li>\n<\/ul>\n<h3>\ub370\uc774\ud130<\/h3>\n<pre><code class=\"r\">library(dplyr)\r\nlibrary(data.table)\r\ndata(mtcars)\r\ndf &lt;- mtcars\r\nTB &lt;- as_tibble(mtcars, rownames='rn')\r\n# rownames='rn'\uc73c\ub85c \ud558\uba74 \ud589\uc774\ub984\uc744 \uc5f4 rn\uc73c\ub85c \ubcf4\uc874\ud55c\ub2e4.\r\nDT &lt;- as.data.table(mtcars, keep.rownames=TRUE) \r\n# keep.rownames = TRUE \ub85c \ub193\uc73c\uba74 \ud589\uc774\ub984\uc774 \uc5f4 rn\uc73c\ub85c \ubcf4\uc874\ub41c\ub2e4.\r\n# \ub370\uc774\ud130\ud14c\uc774\ube14\uacfc \ud2f0\ube14\uc740 \ud589\uc774\ub984(rownames)\ub97c \uc9c0\uc6d0\ud558\uc9c0 \uc54a\ub294\ub2e4.\r\n\r\nprint(head(TB))\r\n<\/code><\/pre>\n<pre>## # A tibble: 6 x 12\r\n##   rn             mpg   cyl  disp    hp  drat    wt  qsec    vs    am  gear  carb\r\n##   &lt;chr&gt;        &lt;dbl&gt; &lt;dbl&gt; &lt;dbl&gt; &lt;dbl&gt; &lt;dbl&gt; &lt;dbl&gt; &lt;dbl&gt; &lt;dbl&gt; &lt;dbl&gt; &lt;dbl&gt; &lt;dbl&gt;\r\n## 1 Mazda RX4     21       6   160   110  3.9   2.62  16.5     0     1     4     4\r\n## 2 Mazda RX4 W~  21       6   160   110  3.9   2.88  17.0     0     1     4     4\r\n## 3 Datsun 710    22.8     4   108    93  3.85  2.32  18.6     1     1     4     1\r\n## 4 Hornet 4 Dr~  21.4     6   258   110  3.08  3.22  19.4     1     0     3     1\r\n## 5 Hornet Spor~  18.7     8   360   175  3.15  3.44  17.0     0     0     3     2\r\n## 6 Valiant       18.1     6   225   105  2.76  3.46  20.2     1     0     3     1\r\n<\/pre>\n<pre><code class=\"r\">print(head(DT))\r\n<\/code><\/pre>\n<pre>##                   rn  mpg cyl disp  hp drat    wt  qsec vs am gear carb\r\n## 1:         Mazda RX4 21.0   6  160 110 3.90 2.620 16.46  0  1    4    4\r\n## 2:     Mazda RX4 Wag 21.0   6  160 110 3.90 2.875 17.02  0  1    4    4\r\n## 3:        Datsun 710 22.8   4  108  93 3.85 2.320 18.61  1  1    4    1\r\n## 4:    Hornet 4 Drive 21.4   6  258 110 3.08 3.215 19.44  1  0    3    1\r\n## 5: Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2\r\n## 6:           Valiant 18.1   6  225 105 2.76 3.460 20.22  1  0    3    1\r\n<\/pre>\n<h3><a id=\"slice\"><\/a><code>slice<\/code><\/h3>\n<ul>\n<li>\ud589\uc744 \uc120\ud0dd\ud558\ub294 <code>slice(TB, c(row1, row2, ...))<\/code>\ub294 \ub370\uc774\ud130\ud14c\uc774\ube14\uc5d0\uc11c <code>DT[c(row1, row2, ...),]<\/code> \ub610\ub294 <code>DT[c(row1, row2, ...)]<\/code>\uc73c\ub85c \ubc88\uc5ed\ud560 \uc218 \uc788\ub2e4.<\/li>\n<li><code>rows = c(row1, row2, ...)<\/code>\uc77c \ub54c, <code>DT[rows,]<\/code>\ub294 \ub370\uc774\ud130\ud504\ub808\uc784(<code>data.frame<\/code>)\uacfc \ub3d9\uc77c\ud55c \ud615\uc2dd\uc774\ub2e4. \ubc18\uba74 <code>DT[rows]<\/code>\ub294 <code>data.frame<\/code>\uc5d0\uc11c\uc640 \ub2e4\ub978 \uc758\ubbf8\ub97c \ub098\ud0c0\ub0c4\uc744 \uc8fc\uc758\ud558\uc790. \ub370\uc774\ud130\ud14c\uc774\ube14\uc5d0\uc11c <code>DT[10]<\/code>\ub294 10\ubc88\uc9f8 \ud589(row)\uc744 \ub098\ud0c0\ub0b8\ub2e4. \ubc18\uba74 \ub370\uc774\ud130\ud504\ub808\uc784\uc5d0\uc11c\ub294 <code>mtcars[10]<\/code>\uc740 10\ubc88\uc9f8 \uc5f4(column)\uc744 \ub098\ud0c0\ub0b8\ub2e4.<\/li>\n<\/ul>\n<pre><code class=\"r\">TB %&gt;% slice(3)\r\nDT[3, ]\r\nDT[3]\r\n<\/code><\/pre>\n<pre>##            rn  mpg cyl disp hp drat   wt  qsec vs am gear carb\r\n## 1: Datsun 710 22.8   4  108 93 3.85 2.32 18.61  1  1    4    1\r\n<\/pre>\n<pre><code class=\"r\">TB %&gt;% slice(c(3, 5))\r\nDT[c(3, 5), ]\r\nDT[c(3, 5)]\r\n<\/code><\/pre>\n<pre>##                   rn  mpg cyl disp  hp drat   wt  qsec vs am gear carb\r\n## 1:        Datsun 710 22.8   4  108  93 3.85 2.32 18.61  1  1    4    1\r\n## 2: Hornet Sportabout 18.7   8  360 175 3.15 3.44 17.02  0  0    3    2\r\n<\/pre>\n<pre><code class=\"r\">rows &lt;- c(1, 5, 6)\r\nTB %&gt;% slice(rows)\r\nDT[rows, ]\r\nDT[rows]\r\n<\/code><\/pre>\n<pre>##                   rn  mpg cyl disp  hp drat   wt  qsec vs am gear carb\r\n## 1:         Mazda RX4 21.0   6  160 110 3.90 2.62 16.46  0  1    4    4\r\n## 2: Hornet Sportabout 18.7   8  360 175 3.15 3.44 17.02  0  0    3    2\r\n## 3:           Valiant 18.1   6  225 105 2.76 3.46 20.22  1  0    3    1\r\n<\/pre>\n<h3><code>filter<\/code><a id=\"filter\"><\/a><\/h3>\n<ul>\n<li>\ud2b9\uc815\ud55c \uc870\uac74\uc744 \ub9cc\uc871\uc2dc\ud0a4\ub294 \ud589\uc744 \uc120\ud0dd\ud558\ub294 <code>filter(TB, cond)<\/code>\ub294 \ub370\uc774\ud130\ud14c\uc774\ube14\uc5d0\uc11c <code>DT[cond,]<\/code>\ub85c \ubc88\uc5ed\ud560 \uc218 \uc788\ub2e4. (\uc774\ub54c <code>cond<\/code>\ub294 \ub17c\ub9ac\ud615 \ubca1\ud130\uc774\ub2e4.)<\/li>\n<li><code>data.table<\/code>\uc740 <code>dplyr<\/code>\uacfc \ub9c8\ucc2c\uac00\uc9c0\ub85c \uceec\ub7fc\uc774\ub984\uc744 \ubc14\ub85c \uc4f8 \uc218 \uc788\ub2e4. \uc544\ub798 \ucf54\ub4dc\uc5d0\uc11c \ub370\uc774\ud130\ud504\ub808\uc784, \ud2f0\ube14, \uadf8\ub9ac\uace0 \ub370\uc774\ud130\ud14c\uc774\ube14\uc744 \ube44\uad50\ud55c\ub2e4.<\/li>\n<\/ul>\n<pre><code class=\"r\"># cyl==4(\uc2e4\ub9b0\ub354\uac00 4\uac1c)\uc774\uace0 gear==5 \uc778 \ud589\r\nmtcars[mtcars$cyl == 4 &amp; mtcars$gear == 5, ]\r\nTB %&gt;% filter(cyl == 4 &amp; gear == 5)\r\nDT[cyl == 4 &amp; gear == 5, ]\r\nDT[cyl == 4 &amp; gear == 5]\r\n<\/code><\/pre>\n<pre>##               rn  mpg cyl  disp  hp drat    wt qsec vs am gear carb\r\n## 1: Porsche 914-2 26.0   4 120.3  91 4.43 2.140 16.7  0  1    5    2\r\n## 2:  Lotus Europa 30.4   4  95.1 113 3.77 1.513 16.9  1  1    5    2\r\n<\/pre>\n<ul>\n<li>\uceec\ub7fc\uc774\ub984\uc744 \ub530\uc634\ud45c \uc5c6\uc774 \uc4f8 \uc218 \uc788\uc5b4\uc11c \ud3b8\ub9ac\ud558\uc9c0\ub9cc, \uceec\ub7fc\uc774\ub984\uc774 \ubca1\ud130\uc5d0 \uc800\uc7a5\ub418\uc5b4 \uc788\uc744 \ub54c\uc5d0\ub294 \ubb38\uc81c\uac00 \uc788\ub2e4. \ub2e4\uc74c\uc758 \uc608\uc81c\uc5d0\ub294 <code>eval()<\/code> \ud568\uc218\ub97c \uc0ac\uc6a9\ud55c \ud574\uacb0\ucc45\uc744 \uc81c\uc2dc\ud55c\ub2e4.<\/li>\n<\/ul>\n<pre><code class=\"r\">coln &lt;- c(\"cyl\", \"gear\")\r\nconds &lt;- c(\"==4\", \"==5\")\r\ncond &lt;- parse(text=paste0(coln, conds, collapse=\" &amp; \"))\r\n\r\nmtcars[with(mtcars, eval(cond)),]\r\nTB %&gt;% filter(eval(cond))\r\nDT[eval(cond),]\r\nDT[eval(cond)]\r\nDT[get(coln[1])==4 &amp; get(coln[2])==5]\r\n<\/code><\/pre>\n<pre>##               rn  mpg cyl  disp  hp drat    wt qsec vs am gear carb\r\n## 1: Porsche 914-2 26.0   4 120.3  91 4.43 2.140 16.7  0  1    5    2\r\n## 2:  Lotus Europa 30.4   4  95.1 113 3.77 1.513 16.9  1  1    5    2\r\n<\/pre>\n<h3><code>select<\/code><a id=\"select\"><\/a><\/h3>\n<p>\uceec\ub7fc\uc744 \uc774\ub984 \ub610\ub294 \uc21c\ubc88\uc73c\ub85c \uc120\ud0dd\ud558\ub294 <code>select(TB, cols)<\/code> \ub610\ub294 <code>select(TB, colA, colB, ...)<\/code>\ub294 <code>DT[,.(cols)]<\/code> \ub610\ub294 <code>DT[,.(colA, colB)]<\/code>\ub85c \ubc88\uc5ed\ud560 \uc218 \uc788\ub2e4. \uc5ec\uae30\uc11c\ub294 <code>mtcars<\/code>\uc758 \ud589\uc744 \ub450 \uac1c\ub9cc \uc120\ud0dd\ud574\uc11c \uc9c4\ud589\ud55c\ub2e4.<\/p>\n<ul>\n<li>\ub370\uc774\ud130<\/li>\n<\/ul>\n<pre><code class=\"r\">DF2 &lt;- mtcars[2:3,]; # \ub370\uc774\ud130\ud504\ub808\uc784(data.frame)\r\nTB2 &lt;- as_tibble(TB) %&gt;% slice(2:3) # \ud2f0\ube14(tibble)\r\nDT2 &lt;- DT[2:3,] # \ub370\uc774\ud130\ud14c\uc774\ube14(data.table)\r\n<\/code><\/pre>\n<h4>\uc5f4 \uc120\ud0dd<\/h4>\n<ul>\n<li>\uc21c\ubc88\uc73c\ub85c \uc5f4\uc120\ud0dd<\/li>\n<\/ul>\n<pre><code class=\"r\">DF2[, c(3, 5)]\r\nTB2 %&gt;% select(c(3, 5))\r\nDT2[, c(3, 5)]\r\n<\/code><\/pre>\n<pre>##    cyl  hp\r\n## 1:   6 110\r\n## 2:   4  93\r\n<\/pre>\n<ul>\n<li>\uc774\ub984\uc73c\ub85c \uc5f4\uc120\ud0dd<\/li>\n<\/ul>\n<pre><code class=\"r\">DF2[, c(\"cyl\", \"hp\")]\r\nTB2 %&gt;% select(c(cyl, hp))\r\nDT2[, .(cyl, hp)]\r\n<\/code><\/pre>\n<pre>##    cyl  hp\r\n## 1:   6 110\r\n## 2:   4  93\r\n<\/pre>\n<ul>\n<li>\ubcc0\uc218\ub85c \uc5f4 \uc21c\ubc88 \uc120\ud0dd<\/li>\n<\/ul>\n<pre><code class=\"r\">icols = c(3, 5)\r\nDF2[, icols]\r\nTB2 %&gt;% select(icols)\r\nDT2[, ..icols]\r\n<\/code><\/pre>\n<pre>##    cyl  hp\r\n## 1:   6 110\r\n## 2:   4  93\r\n<\/pre>\n<ul>\n<li>\ubcc0\uc218\ub85c \uc5f4 \uc774\ub984 \uc120\ud0dd<\/li>\n<\/ul>\n<pre><code class=\"r\">nacols = c(\"cyl\", \"hp\")\r\nDF2[, nacols]\r\nTB2 %&gt;% select_at(nacols)\r\nDT2[, ..nacols]\r\n<\/code><\/pre>\n<pre>##    cyl  hp\r\n## 1:   6 110\r\n## 2:   4  93\r\n<\/pre>\n<p>\uc704\uc5d0\uc11c \uacb0\uacfc \ud074\ub798\uc2a4\ub294 \uc120\ud0dd \uc804 \ud074\ub798\uc2a4\uc640 \ub3d9\uc77c\ud558\ub2e4. \ud558\uc9c0\ub9cc \ub370\uc774\ud130\ud504\ub808\uc784\uc758 \uacbd\uc6b0 \ud558\ub098\uc758 \uc5f4\uc744 \uc120\ud0dd\ud558\uba74 \ubca1\ud130\uac00 \ub41c\ub2e4. \ub370\uc774\ud130\ud14c\uc774\ube14\uc5d0\uc11c \uc5f4 \ud558\ub098\ub97c \uc120\ud0dd\ud574\uc11c \ubca1\ud130\ub97c \uc5bb\ub294 \ubc29\ubc95\uc740 \ub2e4\uc74c\uacfc \uac19\ub2e4.<\/p>\n<pre><code class=\"r\">## \uc21c\ubc88\uc73c\ub85c \uc120\ud0dd\r\nDT2[, 3]  #\ub370\uc774\ud130\ud14c\uc774\ube14\r\nDT2[, 3][[1]]  #\ubca1\ud130\r\n<\/code><\/pre>\n<pre>## [1] 6 4\r\n<\/pre>\n<pre><code class=\"r\">## \uc774\ub984\uc73c\ub85c \uc120\ud0dd\r\nDT2[, .(cyl)]  #\ub370\uc774\ud130\ud14c\uc774\ube14\r\nDT2[, cyl]  # \ubca1\ud130\r\n<\/code><\/pre>\n<pre>## [1] 6 4\r\n<\/pre>\n<pre><code class=\"r\">## \ubcc0\uc218\ub85c \uc21c\ubc88 \uc120\ud0dd\r\nirows = c(3)\r\nDT2[, ..irows]  #\ub370\uc774\ud130\ud14c\uc774\ube14\r\nDT2[, ..irows][[1]]  #\ubca1\ud130\r\n<\/code><\/pre>\n<pre>## [1] 6 4\r\n<\/pre>\n<pre><code class=\"r\">## \ubcc0\uc218\ub85c \uc5f4\uc774\ub984 \uc120\ud0dd\r\nnrows = c(\"cyl\")\r\nDT2[, ..nrows]  # \ub370\uc774\ud130\ud14c\uc774\ube14\r\nDT2[, ..nrows][[1]]  #\ubca1\ud130\r\n<\/code><\/pre>\n<pre>## [1] 6 4\r\n<\/pre>\n<h4>\uc5f4 \uc81c\uc678<\/h4>\n<p>\uc8fc\uc5b4\uc9c4 \uc790\ub8cc\uc5d0\uc11c \uceec\ub7fc\uc744 \uc120\ud0dd\ud560 \ub54c\uc5d0\ub294 \ud544\uc694\ud55c \uceec\ub7fc\uc744 \ub098\uc5f4\ud560 \uc218\ub3c4 \uc788\uc9c0\ub9cc, \ud544\uc694\uc5c6\ub294 \uceec\ub7fc\uc744 \uc81c\uc678\ud560 \uc218\ub3c4 \uc788\ub2e4.<\/p>\n<pre><code class=\"r\">DT2[, -c(3, 4)]  # \uc21c\ubc88\uc73c\ub85c \uc5f4 \uc81c\uc678\r\nicols = c(3, 4)  # \uc21c\ubc88 \ubcc0\uc218\ub85c \uc5f4 \uc81c\uc678\r\nDT2[, -..icols]\r\nDT2[, !..icols]\r\n<\/code><\/pre>\n<pre>##               rn  mpg  hp drat    wt  qsec vs am gear carb\r\n## 1: Mazda RX4 Wag 21.0 110 3.90 2.875 17.02  0  1    4    4\r\n## 2:    Datsun 710 22.8  93 3.85 2.320 18.61  1  1    4    1\r\n<\/pre>\n<pre><code class=\"r\">coln = c(\"cyl\", \"disp\")  # \uc5f4\uc774\ub984 \ubcc0\uc218\ub85c \uc5f4 \uc81c\uc678\r\nDT2[, !..coln]\r\nDT2[, .SD, .SDcols = coln2]\r\n<\/code><\/pre>\n<pre>##               rn  mpg  hp drat    wt  qsec vs am gear carb\r\n## 1: Mazda RX4 Wag 21.0 110 3.90 2.875 17.02  0  1    4    4\r\n## 2:    Datsun 710 22.8  93 3.85 2.320 18.61  1  1    4    1\r\n<\/pre>\n<h3><code>mutate<\/code><a id=\"mutate\"><\/a><\/h3>\n<ul>\n<li><code>dplyr<\/code>\uc758 <code>mutate<\/code>\ub294 \uae30\uc874\uc758 \uceec\ub7fc\uc744 \uc720\uc9c0\ud558\uba74\uc11c \uc77c\ubd80\ub97c \uc218\uc815\ud558\uac70\ub098, \uc0c8\ub85c\uc6b4 \uceec\ub7fc\uc744 \ub9cc\ub4e4\uae30 \uc704\ud574 \uc4f0\uc778\ub2e4.<\/li>\n<li><code>data.table<\/code>\uc5d0\uc11c\ub294 \uc218\uc815 \ub610\ub294 \uc0dd\uc131 \uceec\ub7fc\uc774 \ud558\ub098\uc778 \uacbd\uc6b0, <code>DT[ , newcola := ]<\/code>\ub97c \uc0ac\uc6a9\ud55c\ub2e4. \ub9cc\uc57d \uc0dd\uc131\/\uc218\uc815 \uceec\ub7fc\uc774 \ub450 \uac1c \uc774\uc0c1\uc774\ub77c\uba74 <code>DT[, c('cola','colb'):=list( , )]<\/code> \ub610\ub294 <code>DT[,<\/code> <code>`:=`<\/code> <code>(cola= , colb=)]<\/code>\uc744 \uc0ac\uc6a9\ud55c\ub2e4.<\/li>\n<li><code>data.table<\/code>\uc758 <code>:=<\/code>\ub294 \uc870\uae08 \ud2b9\ubcc4\ud558\ub2e4. <code>:=<\/code>\ub294 \uc0c8\ub85c\uc6b4 \ub370\uc774\ud130 \ud14c\uc774\ube14\uc744 \uc0dd\uc131\ud558\uc9c0 \uc54a\uace0 \uae30\uc874\uc758 \ub370\uc774\ud130 \ud14c\uc774\ube14\uc5d0 \ub36e\uc5b4\uc50c\uc6b0\uac70\ub098(\uc218\uc815), \uc0c8\ub85c\uc6b4 \uceec\ub7fc\uc744 \ucd94\uac00\ud55c\ub2e4.<\/li>\n<\/ul>\n<p>\ub2e4\uc74c\uc758 \uc608\uc81c\ub294 <code>hp*qsec<\/code>\uc744 \uad6c\ud574\uc11c <code>wt2<\/code>\ub77c\ub294 \uceec\ub7fc \uc774\ub984\uc73c\ub85c \uc800\uc7a5\ud55c\ub2e4. \uadf8\ub9ac\uace0 <code>hp<\/code>, <code>qsec<\/code>\ub77c\ub294 \uceec\ub7fc\uc740 <code>hp*2<\/code>, <code>qsec*2<\/code>\ub85c \uc218\uc815\ud55c\ub2e4.<\/p>\n<pre><code class=\"r\"># \ub370\uc774\ud130\r\nDF3 &lt;- DF2[, c(\"hp\", \"qsec\")]\r\nTB3 &lt;- TB2 %&gt;% select(hp, qsec)\r\nDT3 &lt;- DT2[, .(hp, qsec)]\r\n<\/code><\/pre>\n<ul>\n<li>\ud558\ub098\uc758 \uceec\ub7fc \uc0dd\uc131\/\uc218\uc815<\/li>\n<\/ul>\n<pre><code class=\"r\">DF3[, \"wt2\"] = DF3$hp * DF3$qsec\r\nDF3$wt2 = DF3$hp * DF3$qsec\r\nDF3[[\"wt2\"]] = DF3$hp * DF3$qsec\r\nTB3 %&gt;% mutate(wt2 = hp * qsec)\r\nDT3[, `:=`(wt2, hp * qsec)]\r\nprint(DT3)\r\n<\/code><\/pre>\n<pre>##     hp  qsec     wt2\r\n## 1: 110 17.02 1872.20\r\n## 2:  93 18.61 1730.73\r\n<\/pre>\n<ul>\n<li>\ub458 \uc774\uc0c1\uc758 \uceec\ub7fc \uc0dd\uc131\/\uc218\uc815<\/li>\n<\/ul>\n<pre><code class=\"r\">DF3[, c(\"hp\", \"qsec\")] = data.frame(DF3$hp * 2, DF3$qsec * 2)\r\nTB3 &lt;- TB3 %&gt;% mutate(hp = hp * 2, qsec = qsec * 2)\r\nDT3[, `:=`(c(\"hp\", \"qsec\"), list(hp * 2, qsec * 2))]\r\nDT3[, `:=`(hp = hp * 2, qsec = qsec * 2)]\r\nprint(DT3)\r\n<\/code><\/pre>\n<pre>##     hp  qsec     wt2\r\n## 1: 220 34.04 1872.20\r\n## 2: 186 37.22 1730.73\r\n<\/pre>\n<ul>\n<li>\uceec\ub7fc \uc774\ub984 \ubcc0\uc218: \ud558\ub098\uc758 \uceec\ub7fc \uc0dd\uc131\/\uc218\uc815<\/li>\n<\/ul>\n<pre><code class=\"r\">coln = \"wt2\"\r\nDF3[, coln] = DF3$hp * DF3$qsec\r\nDF3[[coln]] = DF3$hp * DF3$qsec\r\nTB3 &lt;- TB2 %&gt;% mutate_at(coln, funs(hp * qsec))\r\nDT3[, `:=`(c(coln), hp * qsec)]\r\n<\/code><\/pre>\n<pre>##     hp  qsec     wt2     cyl    disp\r\n## 1: 220 34.04 1872.20 7488.80 7488.80\r\n## 2: 186 37.22 1730.73 6922.92 6922.92\r\n<\/pre>\n<ul>\n<li>\uceec\ub7fc \uc774\ub984 \ubcc0\uc218: \uc5ec\ub7ec \uceec\ub7fc \uc0dd\uc131\/\uc218\uc815<\/li>\n<\/ul>\n<pre><code class=\"r\">coln = c(\"hp\", \"qsec\")\r\nDF3[, coln] = lapply(DF3[, coln], function(x) x * 2)\r\nDF3[, coln] = do.call(data.frame, lapply(DF3[, coln], function(x) x * 2))\r\nTB3 &lt;- TB3 %&gt;% mutate_at(coln, funs(. * 2))\r\nDT3[, `:=`(c(coln), lapply(.SD, function(x) x * 2)), .SDcols = coln]\r\nprint(DT3)\r\n<\/code><\/pre>\n<pre>##     hp  qsec     wt2      cyl     disp\r\n## 1: 220 34.04 1872.20 14977.60 14977.60\r\n## 2: 186 37.22 1730.73 13845.84 13845.84\r\n<\/pre>\n<h3><code>transmute<\/code><a id=\"transmute\"><\/a><\/h3>\n<p><code>dplyr<\/code>\uc758 <code>transmute<\/code>\ub294 \uae30\uc874\uc758 \uceec\ub7fc\uc744 \uc81c\uc678\ud558\uace0 \uc0c8\ub86d\uac8c \uc0dd\uc131\ub41c \uceec\ub7fc\ub9cc\uc744 \ubcf4\uc874\ud55c\ub2e4.<\/p>\n<p><code>data.table<\/code>\uc5d0\uc11c <code>=<\/code>\ub294 \uc0c8\ub85c\uc6b4 \uceec\ub7fc\uc744 \uc0dd\uc131\ud558\uace0, \uc704\uc5d0\uc11c \ubd24\ub358 <code>:=<\/code>\ub294 \uae30\uc874\uc758 \uceec\ub7fc\uc744 \uc218\uc815\ud55c\ub2e4. <code>data.table<\/code>\uc5d0\uc11c <code>=<\/code>\uc744 \uc0ac\uc6a9\ud560 \ub54c\uc5d0\ub294 \uacb0\uacfc\uac00 \uae30\uc874\uc758 \ub370\uc774\ud130 \ud14c\uc774\ube14\uacfc \uac19\uc740 \ud06c\uae30\uc77c \ud544\uc694\uac00 \uc5c6\ub2e4.<\/p>\n<ul>\n<li>\ud558\ub098\uc758 \uceec\ub7fc \uc0dd\uc131\/\uc218\uc815<\/li>\n<\/ul>\n<pre><code class=\"r\">DF4 = data.frame(wt2 = DF3$hp * DF3$qsec)\r\nTB4 &lt;- TB3 %&gt;% transmute(wt2 = hp*qsec)\r\nDT4 &lt;- DT3[, .(wt3=hp*qsec)]; print(DT4)\r\n<\/code><\/pre>\n<pre>##        wt3\r\n## 1: 7488.80\r\n## 2: 6922.92\r\n<\/pre>\n<ul>\n<li>\ub458 \uc774\uc0c1\uc758 \uceec\ub7fc \uc0dd\uc131\/\uc218\uc815<\/li>\n<\/ul>\n<pre><code class=\"r\">DF4 = data.frame(hp2 = DF3$hp * 2, qsec2 = DF3$qsec * 2)\r\nDF4 = with(DF3, data.frame(hp2 = hp * 2, qsec2 = qsec * 2))\r\nTB4 &lt;- TB3 %&gt;% transmute(hp = hp * 2, qsec = qsec * 2)\r\nTB4 &lt;- TB3 %&gt;% transmute_at(c(\"hp\", \"qsec\"), funs(. * 2))\r\nDT4 &lt;- DT3[, .(hp2 = hp * 2, qsec2 = qsec * 2)]\r\nDT4 &lt;- DT3[, lapply(.SD, function(x) x * 2), .SDcols = c(\"hp\", \"qsec\")]\r\nprint(DT4)\r\n<\/code><\/pre>\n<pre>##     hp  qsec\r\n## 1: 440 68.08\r\n## 2: 372 74.44\r\n<\/pre>\n<ul>\n<li>\ubcc0\uc218: \ud558\ub098\uc758 \uceec\ub7fc \uc0dd\uc131\/\uc218\uc815<\/li>\n<\/ul>\n<pre><code class=\"r\">coln = \"wt2\"\r\nDF4 = data.frame(DF3$hp * DF3$qsec)\r\ncolnames(DF4) = coln\r\nTB4 &lt;- TB3 %&gt;% transmute(hp * qsec)\r\ncolnames(TB4) = coln\r\nDT4 &lt;- DT3[, .(hp * qsec)]\r\ncolnames(DT4) = coln\r\nprint(DT4)\r\n<\/code><\/pre>\n<pre>##        wt2\r\n## 1: 7488.80\r\n## 2: 6922.92\r\n<\/pre>\n<ul>\n<li>\ubcc0\uc218: \uc5ec\ub7ec \uceec\ub7fc \uc0dd\uc131\/\uc218\uc815<\/li>\n<\/ul>\n<pre><code class=\"r\">coln = c(\"hp\", \"qsec\")\r\nDF4 &lt;- do.call(data.frame, lapply(DF3[, coln], function(x) x * 2))\r\nTB4 &lt;- TB3 %&gt;% transmute_at(coln, funs(. * 2))\r\nDT4 &lt;- DT3[, lapply(.SD, function(x) x * 2), .SDcols = coln]\r\nprint(DT4)\r\n<\/code><\/pre>\n<pre>##     hp  qsec\r\n## 1: 440 68.08\r\n## 2: 372 74.44\r\n<\/pre>\n<h3><code>arrange<\/code><a id=\"arrange\"><\/a><\/h3>\n<ul>\n<li>\ub370\uc774\ud130<\/li>\n<\/ul>\n<pre><code class=\"r\">DF5 &lt;- mtcars[c(2:5), 1:4]\r\nTB5 &lt;- as_tibble(mtcars) %&gt;% slice(2:5) %&gt;% select(1:4)\r\nDT5 &lt;- as.data.table(mtcars, keep.rownames = TRUE)[2:5, c(1:4)]\r\nprint(DT5)\r\n<\/code><\/pre>\n<pre>##                   rn  mpg cyl disp\r\n## 1:     Mazda RX4 Wag 21.0   6  160\r\n## 2:        Datsun 710 22.8   4  108\r\n## 3:    Hornet 4 Drive 21.4   6  258\r\n## 4: Hornet Sportabout 18.7   8  360\r\n<\/pre>\n<p><code>dplyr<\/code>\uc758 <code>arrange(TB, col1, desc(col2))<\/code>\ub294 \ub370\uc774\ud130\ud14c\uc774\ube14\uc5d0\uc11c <code>DT[order(col1, -col2)]<\/code>\ub85c \ubc88\uc5ed\ud560 \uc218 \uc788\ub2e4. \ub370\uc774\ud130\ud14c\uc774\ube14\uc758 <code>order<\/code>\ub294 \ubb38\uc790\ud615\uc774\ub098 \uc21c\uc704\ud615 \uceec\ub7fc\uc5d0 \ub300\ud574\uc11c\ub3c4 <code>order(-col)<\/code> \ud615\ud0dc\ub85c \uc4f8 \uc218 \uc788\ub2e4.<\/p>\n<pre><code class=\"r\">DF5[order(DF5$cyl, -DF5$mpg),]\r\nTB5 %&gt;% arrange(cyl, desc(mpg))\r\nDT5[order(cyl, -mpg),]; DT5[order(cyl, -mpg)]\r\n<\/code><\/pre>\n<pre>##                   rn  mpg cyl disp\r\n## 1:        Datsun 710 22.8   4  108\r\n## 2:    Hornet 4 Drive 21.4   6  258\r\n## 3:     Mazda RX4 Wag 21.0   6  160\r\n## 4: Hornet Sportabout 18.7   8  360\r\n<\/pre>\n<h3><code>group_by<\/code><a id=\"groupby\"><\/a><\/h3>\n<ul>\n<li><code>dplyr<\/code>\uc758 <code>group_by(byG)<\/code>\ub294 <code>DT[ , , byG]<\/code>\ub85c \ubc88\uc5ed\ud560 \uc218 \uc788\ub2e4.<\/li>\n<li>\ubcf4\ud1b5 <code>group_by<\/code>\ub294 \ud640\ub85c \uc4f0\uc774\uc9c0 \uc54a\uace0, <code>group_by() %&gt;% summarise()<\/code> \ub610\ub294 <code>group_by() %&gt;% do()<\/code> \ub610\ub294 <code>group_by() %&gt;% arrange()<\/code>\ub85c \uad6c\ubb38\uc73c\ub85c \ub9ce\uc774 \uc4f0\uc778\ub2e4.<\/li>\n<li><code>group_by(byG) %&gt;% summarsize(fn_sum)<\/code> \ub610\ub294 <code>group_by(byG) %&gt;% do(fn_do)<\/code>\ub294 \ubaa8\ub450 <code>DT[ , fn_sum, byG]<\/code> \ub610\ub294 <code>DT[ , fn_do, byG]<\/code>\ub85c \ub098\ud0c0\ub0bc \uc788\ub2e4.<\/li>\n<li>\ubcf4\ud1b5 \ub370\uc774\ud130 \ud14c\uc774\ube14\uc740 <code>DT[i, j, byG]<\/code>\ub85c \ub098\ud0c0\ub0b4\ub294 \ub370, \uc5ec\uae30\uc11c <code>j<\/code>\ub294 \uc55e\uc5d0\uc11c \ubd24\ub358 \uceec\ub7fc\uc744 \uc120\ud0dd\ud558\ub294 \uac83 \uc774\uc0c1\uc744 \uc218\ud589\ud560 \uc218 \uc788\ub2e4. \uc5ec\ub7ec \uac00\uc9c0 \ud568\uc218\ub97c \uc0ac\uc6a9\ud560 \uc218 \uc788\ub294 \ub370 \uc720\uc77c\ud55c \uc81c\ud55c \uc870\uac74\uc740 \uadf8 \uacb0\uacfc\uac00 \ub9ac\uc2a4\ud2b8\uc5ec\uc57c \ud55c\ub2e4\ub294 \uac83\uc774\ub2e4.<\/li>\n<\/ul>\n<pre><code class=\"r\">DF6 &lt;- mtcars[c(10:2), c(\"mpg\", \"cyl\", \"disp\", \"hp\", \"am\")]\r\nTB6 &lt;- TB %&gt;% slice(10:2) %&gt;% select(mpg, cyl, disp, hp, am)\r\nDT6 &lt;- DT[10:2, .(mpg, cyl, disp, hp, am)]\r\nprint(head(DT6))\r\n<\/code><\/pre>\n<pre>##     mpg cyl  disp  hp am\r\n## 1: 19.2   6 167.6 123  0\r\n## 2: 22.8   4 140.8  95  0\r\n## 3: 24.4   4 146.7  62  0\r\n## 4: 14.3   8 360.0 245  0\r\n## 5: 18.1   6 225.0 105  0\r\n## 6: 18.7   8 360.0 175  0\r\n<\/pre>\n<ul>\n<li><code>cyl<\/code>\uc744 \uae30\uc900\uc73c\ub85c \uc9d1\ub2e8\uc744 \ubd84\ub9ac\ud55c \ud6c4 \uac01 \uc9d1\ub2e8\uc758 <code>mpg<\/code> \ud3c9\uade0\uc744 \uad6c\ud558\ub294 \ubc29\ubc95\uc740 \ub2e4\uc74c\uacfc \uac19\ub2e4. \ub370\uc774\ud130\ud14c\uc774\ube14\uc5d0\uc11c <code>key=<\/code>\uc744 \uc4f0\uba74 \uae30\uc900 \ubcc0\uc218\uc5d0 \ub300\ud55c \uc815\ub82c\uc774 \uc774\ub8e8\uc5b4\uc9c0\uc9c0 \uc54a\uc73c\uba70(\ubcc0\uc218\uc758 \uc21c\uc11c\ub294 \uc6d0 \uc790\ub8cc\uc758 \uc21c\uc11c\uc640 \uac19\ub2e4), <code>keyby=<\/code>\ub97c \uc4f0\uba74 \uc815\ub82c\uc774 \uc774\ub8e8\uc5b4\uc9c4\ub2e4.<\/li>\n<\/ul>\n<pre><code class=\"r\">aggregate(mpg ~ cyl, data = DF6, FUN = mean)\r\nTB6 %&gt;% group_by(cyl) %&gt;% summarise(mpg = mean(mpg))\r\nDT6[, mean(mpg), cyl]  # cyl\ub294 \uc815\ub82c\ub418\uc9c0 \uc54a\ub294\ub2e4.  \r\nDT6[, .(mpg = mean(mpg)), by = cyl]  # cyl\ub294 \uc815\ub82c\ub418\uc9c0 \uc54a\ub294\ub2e4.\r\nDT6[, mean(mpg), keyby = cyl]  # cyl\ub294 \uc815\ub82c\ub41c\ub2e4.\r\n<\/code><\/pre>\n<pre>##    cyl      mpg\r\n## 1:   6 19.92500\r\n## 2:   4 23.33333\r\n## 3:   8 16.50000\r\n<\/pre>\n<pre>##    cyl       V1\r\n## 1:   4 23.33333\r\n## 2:   6 19.92500\r\n## 3:   8 16.50000\r\n<\/pre>\n<ul>\n<li>\ub9cc\uc57d \uc9d1\ub2e8\uc744 \ub098\ub204\ub294 \uae30\uc900\uc744 \ub450 \ubcc0\uc218(<code>am<\/code>, <code>cyl<\/code>)\ub85c \ud558\uace0 <strong>\ub450 \ubcc0\uc218(<code>mpg<\/code>, <code>hp<\/code>)\uc758 \ud3c9\uade0<\/strong>\uc744 \uad6c\ud558\uace0 \uc2f6\ub2e4\uba74 \ub2e4\uc74c\uacfc \uac19\ub2e4.<\/li>\n<\/ul>\n<pre><code class=\"r\">aggregate(cbind(mpg, hp) ~ am + cyl, data = DF6, FUN = mean)\r\nTB6 %&gt;% group_by(cyl, am) %&gt;% summarise(mpg = mean(mpg), hp = mean(hp))\r\nDT6[, .(mpg = mean(mpg), hp = mean(hp)), by = .(cyl, am)]\r\nDT6[, .(mpg = mean(mpg), hp = mean(hp)), keyby = .(cyl, am)]\r\n<\/code><\/pre>\n<pre>##   am cyl      mpg       hp\r\n## 1  0   4 23.60000  78.5000\r\n## 2  1   4 22.80000  93.0000\r\n## 3  0   6 19.56667 112.6667\r\n## 4  1   6 21.00000 110.0000\r\n## 5  0   8 16.50000 210.0000\r\n<\/pre>\n<pre>## # A tibble: 5 x 4\r\n## # Groups:   cyl [?]\r\n##     cyl    am   mpg    hp\r\n##   &lt;dbl&gt; &lt;dbl&gt; &lt;dbl&gt; &lt;dbl&gt;\r\n## 1     4     0  23.6  78.5\r\n## 2     4     1  22.8  93  \r\n## 3     6     0  19.6 113. \r\n## 4     6     1  21   110  \r\n## 5     8     0  16.5 210\r\n<\/pre>\n<pre>##    cyl am      mpg       hp\r\n## 1:   6  0 19.56667 112.6667\r\n## 2:   4  0 23.60000  78.5000\r\n## 3:   8  0 16.50000 210.0000\r\n## 4:   4  1 22.80000  93.0000\r\n## 5:   6  1 21.00000 110.0000\r\n<\/pre>\n<pre>##    cyl am      mpg       hp\r\n## 1:   4  0 23.60000  78.5000\r\n## 2:   4  1 22.80000  93.0000\r\n## 3:   6  0 19.56667 112.6667\r\n## 4:   6  1 21.00000 110.0000\r\n## 5:   8  0 16.50000 210.0000\r\n<\/pre>\n<ul>\n<li>\ub9cc\uc57d \uae30\uc900\uc73c\ub85c \uc0ac\uc6a9\ub418\uc9c0 \uc54a\uc740 \ubaa8\ub4e0 \uc5f4\uc5d0 \ub300\ud574 \ud3c9\uade0\uc744 \uad6c\ud55c\ub2e4\uba74 \ub2e4\uc74c\uacfc \uac19\ub2e4. <code>aggregate<\/code>\uc5d0\uc11c <code>.<\/code>\uc740 \ub098\uba38\uc9c0 \uc5f4\uc744 \uc758\ubbf8\ud55c\ub2e4.<\/li>\n<\/ul>\n<pre><code class=\"r\">aggregate(. ~ am + cyl, data = DF6, FUN = mean)\r\nTB6 %&gt;% group_by(cyl, am) %&gt;% summarise_all(mean)\r\nDT6[, lapply(.SD, mean), by = .(cyl, am)]  # cyl, am\uc5d0 \ub300\ud574 \uc815\ub82c\ub418\uc9c0 \uc54a\uc74c\r\nDT6[, lapply(.SD, mean), keyby = .(cyl, am)]  # cyl, am\uc5d0 \ub300\ud574 \uc815\ub82c\r\n<\/code><\/pre>\n<pre>##    cyl am      mpg     disp       hp\r\n## 1:   6  0 19.56667 216.8667 112.6667\r\n## 2:   4  0 23.60000 143.7500  78.5000\r\n## 3:   8  0 16.50000 360.0000 210.0000\r\n## 4:   4  1 22.80000 108.0000  93.0000\r\n## 5:   6  1 21.00000 160.0000 110.0000\r\n<\/pre>\n<pre>##    cyl am      mpg     disp       hp\r\n## 1:   4  0 23.60000 143.7500  78.5000\r\n## 2:   4  1 22.80000 108.0000  93.0000\r\n## 3:   6  0 19.56667 216.8667 112.6667\r\n## 4:   6  1 21.00000 160.0000 110.0000\r\n## 5:   8  0 16.50000 360.0000 210.0000\r\n<\/pre>\n<ul>\n<li><code>group_by() %&gt;% summarise() %&gt;% arrange()<\/code>\uc758 \uacbd\uc6b0\ub294 \ub2e4\uc74c\uacfc \uac19\uc774 <code>[]<\/code>\uc758 \uc5f0\uc1c4\ub97c \ud65c\uc6a9\ud558\uba74 \ub41c\ub2e4.<\/li>\n<\/ul>\n<pre><code class=\"r\">DF6 &lt;- aggregate(cbind(mpg, hp) ~ am + cyl, data=DF6, FUN=mean);\r\nDF6[order(DF6$mpg),] \r\nTB6 %&gt;% group_by(cyl, am) %&gt;% summarise(mpg=mean(mpg), hp=mean(hp)) %&gt;%\r\n  arrange(mpg) \r\nDT6[, .(mpg = mean(mpg), hp = mean(hp)), by=.(cyl, am)][order(mpg)]\r\nDT6[, .(mpg = mean(mpg), hp = mean(hp)), keyby=.(cyl, am)][order(mpg)] \r\n<\/code><\/pre>\n<pre>##    cyl am      mpg       hp\r\n## 1:   8  0 16.50000 210.0000\r\n## 2:   6  0 19.56667 112.6667\r\n## 3:   6  1 21.00000 110.0000\r\n## 4:   4  1 22.80000  93.0000\r\n## 5:   4  0 23.60000  78.5000\r\n<\/pre>\n<pre>##    cyl am      mpg       hp\r\n## 1:   8  0 16.50000 210.0000\r\n## 2:   6  0 19.56667 112.6667\r\n## 3:   6  1 21.00000 110.0000\r\n## 4:   4  1 22.80000  93.0000\r\n## 5:   4  0 23.60000  78.5000\r\n<\/pre>\n<h3>\uc885\ud569<a id=\"summary\"><\/a><\/h3>\n<ul>\n<li><code>data.table<\/code>\uc758 \ubb38\ubc95\uc740 <code>DT[i, j, by\/keyby=, .SDcols= ][]<\/code>\ub85c \ub098\ud0c0\ub0bc \uc218 \uc788\ub2e4.\n<ul>\n<li><code>i<\/code>\ub294 \ud589\uc744 \uc120\ud0dd\ud558\uac70\ub098 \uc21c\uc11c\ub97c \uc870\uc815\ud55c\ub2e4.<\/li>\n<li><code>j<\/code>\ub294 \uc5f4\uc744 \uc120\ud0dd\ud558\uac70\ub098, \uc5f4 \ub610\ub294 \ub370\uc774\ud130 \ud14c\uc774\ube14 \uc804\uccb4(<code>.SD<\/code>)\uc5d0 \uc5b4\ub5a4 \ud568\uc218\ub97c \uc801\uc6a9\ud55c\ub2e4.<\/li>\n<li><code>by<\/code>(\ub610\ub294 <code>keyby<\/code>)\ub294 \uc9d1\ub2e8\uc744 \ub098\ub208\ub2e4.<\/li>\n<li><code>.SDcols=<\/code>\ub294 <code>j<\/code>\ub97c \uc218\ud589\ud558\uae30 \uc774\uc804\uc5d0 \uc5f4\uc744 \uc120\ud0dd\ud55c\ub2e4.<\/li>\n<li>\ub9c8\uc9c0\ub9c9\uc758 <code>[]<\/code>\ub294 \uc0dd\ub7b5\ud558\uac70\ub098, \uc5f4\uc744 \uc815\ub82c\ud558\uac70\ub098(<code>[order()]<\/code>), <code>:=<\/code>\uc774\ud6c4\uc5d0 \ub370\uc774\ud130 \ud14c\uc774\ube14\uc744 \ucd9c\ub825\ud560 \ub54c(<code>[]<\/code>) \uc0ac\uc6a9\ud560 \uc218 \uc788\ub2e4.<\/li>\n<\/ul>\n<\/li>\n<li><code>dplyr<\/code>\uacfc\uc758 \ube44\uad50<\/li>\n<\/ul>\n<table>\n<thead>\n<tr>\n<th align=\"left\"><code>dplyr<\/code><\/th>\n<th align=\"left\"><code>data.table<\/code><\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td align=\"left\"><code>slice(1:10)<\/code><\/td>\n<td align=\"left\"><code>DT[1:10]<\/code><\/td>\n<\/tr>\n<tr>\n<td align=\"left\"><code>filter(cola == 3)<\/code><\/td>\n<td align=\"left\"><code>DT[cola==3]<\/code><\/td>\n<\/tr>\n<tr>\n<td align=\"left\"><code>select(cola, colb)<\/code><\/td>\n<td align=\"left\"><code>DT[.(cola, colb)]<\/code><\/td>\n<\/tr>\n<tr>\n<td align=\"left\"><code>mutate(colc = cola*colb)<\/code><\/td>\n<td align=\"left\"><code>DT[, colc := cola*colb]<\/code><\/td>\n<\/tr>\n<tr>\n<td align=\"left\"><code>transmute(colc = cola*colb)<\/code><\/td>\n<td align=\"left\"><code>DT[, .(colc=cola*colb)]<\/code><\/td>\n<\/tr>\n<tr>\n<td align=\"left\"><code>arrange(cola)<\/code><\/td>\n<td align=\"left\"><code>DT[order(cola)]<\/code><\/td>\n<\/tr>\n<tr>\n<td align=\"left\"><code>group_by(cola)<\/code><\/td>\n<td align=\"left\"><code>DT[,,by=cola]<\/code><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h4><code>example(data.table)<\/code><\/h4>\n<p><a href=\"https:\/\/github.com\/Rdatatable\/data.table\/wiki\"><code>data.table<\/code>\uc758 \ud648\ud398\uc774\uc9c0<\/a>\uc5d0\uc11c\ub3c4 \ud655\uc778\ud560 \uc218 \uc788\ub4ef\uc774, <code>example(data.table)<\/code>\uc744 \ud1b5\ud574 <code>data.table<\/code>\uc758 \uc8fc\uc694 \uae30\ub2a5\uc744 \ud655\uc778\ud560 \uc218 \uc788\ub2e4. <code>example(data.table)<\/code>\uc758 \uacb0\uacfc\ub97c \ubcf4\uace0 \uc5bc\ub9c8\ub098 \uc774\ud574\ud560 \uc218 \uc788\ub294\uc9c0 \ud655\uc778\ud574 \ubcf4\uc790.<\/p>\n<pre><code class=\"r\">example(data.table)\r\n<\/code><\/pre>\n<p><code>example(data.table)<\/code>\uc758 \uacb0\uacfc\uc5d0\uc11c \uc0dd\uc18c\ud55c \ubd80\ubd84\uc740 <code>on=<\/code>, <code>nomatch=<\/code>, <code>roll=<\/code>, <code>.EACHI<\/code>, <code>mult=<\/code>, <code>copy()<\/code>, <code>setkey()<\/code>, <code>haskey()<\/code>, <code>.I<\/code>, <code>.GRP<\/code>, <code>.BY<\/code> \ub4f1\uc774 \uc788\ub2e4.<\/p>\n<p>\uc774\ub4e4\uc774 \ud544\uc694\ud55c \uae30\ub2a5\uc5d0 \ub530\ub77c \uad6c\ubd84\ud574 \ubcf4\uba74 \ub2e4\uc74c\uacfc \uac19\ub2e4.<\/p>\n<ul>\n<li>\ub370\uc774\ud130\ud14c\uc774\ube14\uc5d0 \ud0a4 \uc124\uc815 \ubc0f \ud65c\uc6a9 : <code>setkey()<\/code>, <code>haskey()<\/code>, <code>J()<\/code><\/li>\n<li>\ub450 \ub370\uc774\ud130\ud14c\uc774\ube14\uc758 \ubcd1\ud569(\uc870\uc778) : <code>on=<\/code>, <code>nomatch=<\/code>, <code>roll=<\/code>, <code>mult=<\/code><\/li>\n<li>\ud2b9\ubcc4\ud55c \uae30\ub2a5\uc744 \ud558\ub294 \ubcc0\uc218 : <code>.I<\/code>, <code>.GRP<\/code>, <code>.BY<\/code>, <code>.EACHI<\/code><\/li>\n<\/ul>\n<p>\ub2e4\uc74c\uc5d0\ub294 \uc774\ub4e4\uc5d0 \ub300\ud574 \ucc28\ub840\ub85c \uc54c\uc544\ubcfc \uacc4\ud68d\uc774\ub2e4.<\/p>\n<hr \/>\n<p>\uc774 \uae00\uc740 <a href=\"https:\/\/book.naver.com\/bookdb\/book_detail.nhn?bid=14572251\">R\ub85c \ud558\ub294 \ube45\ub370\uc774\ud130 \ubd84\uc11d: \ub370\uc774\ud130 \uc804\ucc98\ub9ac\uc640 \uc2dc\uac01\ud654-\uac1c\ub150\uc801 \uae30\ucd08\uc5d0\uc11c \uc2ec\uce35\ud65c\uc6a9\uae4c\uc9c0<\/a>\uc758 \ub0b4\uc6a9\uc744 \uc870\uae08 \uac01\uc0c9\ud55c \uac83\uc785\ub2c8\ub2e4.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\ud328\ud0a4\uc9c0 \ub370\uc774\ud130\ud14c\uc774\ube14(data.table) package:dplyr\uacfc package:data.table\uc758 \ube44\uad50 package:data.table\ub294 \ub300\uc6a9\ub7c9\uc758 \ub370\uc774\ud130\ub97c \ubd84\uc0b0 \ucc98\ub9ac \uc2dc\uc2a4\ud15c\uc758 \ub3c4\uc6c0\uc5c6\uc774 \ucc98\ub9ac\ud560 \uc218 \uc788\ub294 \ucd5c\uc120\uc758 \ubc29\ubc95\uc774\ub2e4. \uc5ec\ub7ec \ubca4\uce58\ub9c8\ud0b9 \uacb0\uacfc\ub294 \ub370\uc774\ud130\ud14c\uc774\ube14(data.table)\uc774 \ube45\ub370\uc774\ud130\ub97c \ucc98\ub9ac\ud558\ub294\ub370 \ud0c0\uc758 \ucd94\uc885\uc744 \ubd88\ud5c8\ud568\uc744 \ubcf4\uc5ec\uc8fc\uc5c8\ub2e4. \uadf8\ub7ec\ub098 \uc804\ud1b5\uc801\uc778 R\uc758 \ubb38\ubc95\uacfc \uc0c1\uc774\ud558\uace0, \ub2e4\uc18c \ub09c\ud574\ud55c \ubb38\ubc95 \ub54c\ubb38\uc5d0 \ub110\ub9ac \uc0ac\uc6a9\ub418\uc9c0 \ubabb\ud558\ub294 \ub4ef \ud558\ub2e4. \uc5ec\uae30\uc11c\ub294 \uc77d\uae30 \uc26c\uc6b4 package:dplyr\uc758 \uc5ec\ub7ec \ud568\uc218(slice, filter \ub4f1)\uc744 package:data.table\ub85c \ubc88\uc5ed\ud558\uc5ec, \ub370\uc774\ud130\ud14c\uc774\ube14\uc758 \uc811\uadfc\uc131\uc744 \ub192\uc774\ub824 \ud558\uc600\ub2e4. [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":1043,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[28,114,207,179],"tags":[84,208,184,74,186,83,73,185,182],"jetpack_featured_media_url":"http:\/\/ds.sumeun.org\/wp-content\/uploads\/2019\/03\/datatable_part01.png","_links":{"self":[{"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=\/wp\/v2\/posts\/1035"}],"collection":[{"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1035"}],"version-history":[{"count":8,"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=\/wp\/v2\/posts\/1035\/revisions"}],"predecessor-version":[{"id":1044,"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=\/wp\/v2\/posts\/1035\/revisions\/1044"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=\/wp\/v2\/media\/1043"}],"wp:attachment":[{"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1035"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1035"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1035"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}