{"id":2215,"date":"2020-08-01T02:20:48","date_gmt":"2020-07-31T17:20:48","guid":{"rendered":"http:\/\/141.164.34.82\/?p=2215"},"modified":"2020-08-01T02:23:29","modified_gmt":"2020-07-31T17:23:29","slug":"r-data-table%eb%8d%b0%ec%9d%b4%ed%84%b0-%ed%85%8c%ec%9d%b4%eb%b8%94","status":"publish","type":"post","link":"http:\/\/ds.sumeun.org\/?p=2215","title":{"rendered":"R data.table(\ub370\uc774\ud130 \ud14c\uc774\ube14)"},"content":{"rendered":"<h2>R <code>data.table<\/code><\/h2>\n<ul>\n<li><a href=\"https:\/\/github.com\/shinykorea\/Meetup\">R shiny Korea meetup<\/a>\uc5d0\uc11c <a href=\"https:\/\/github.com\/kwhkim\/rshinymeetup17\">R \ub370\uc774\ud130 \ud14c\uc774\ube14\uc744 \uc18c\uac1c\ud558\ub294 \ubc1c\ud45c<\/a>\ub97c \ud588\uc2b5\ub2c8\ub2e4.<\/li>\n<\/ul>\n<h2>CRUD(Create\/Read\/Update\/Delete)<\/h2>\n<p>CRUD \uc815\ub3c4\ub294 <code>DT[i\/filter, j\/summarise, by]<\/code> \uc815\ub3c4\uc5d0\uc11c \ubaa8\ub450 \ub05d\ub0bc \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/p>\n<p><code>DT[i, j\/summarise\/func, by]<\/code>\uc5d0\uc11c <code>j\/summarise\/func<\/code> \ubd80\ubd84\uc744 \ubd05\uc2dc\ub2e4. \uc774 \ubd80\ubd84\uc5d0\uc11c \ub370\uc774\ud130\ud14c\uc774\ube14\uc758 \uc5f4(column)\uc744 \uc120\ud0dd\ud558\uac70\ub098, \uc5f4\uc744 \uc694\uc57d\ud558\ub294 \ud568\uc218\ub97c \uc801\uc6a9\ud558\uac70\ub098, \uc77c\ubc18\uc801\uc778 \ud568\uc218\ub97c \uc801\uc6a9\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4.<\/p>\n<ol>\n<li>\uc5f4 : <code>DT[, c(2,3)]<\/code><\/li>\n<li>\uc694\uc57d : <code>DT[, mean(hp), cyl]<\/code><\/li>\n<li>\uc77c\ubc18\uc801\uc778 \ud568\uc218 : <code>DT[, plot(hp~mpg)]<\/code><\/li>\n<\/ol>\n<p>\uc2e4\uc81c\ub85c \ud574\ubcfc\uae4c\uc694?<\/p>\n<pre><code class=\"r\">library(data.table)\r\nlibrary(dplyr)\r\ndata(mtcars)\r\nDT = data.table(mtcars)\r\n<\/code><\/pre>\n<pre><code class=\"r\">DT[,c(2,3)] %&gt;% head\r\n<\/code><\/pre>\n<pre>##    cyl disp\r\n## 1:   6  160\r\n## 2:   6  160\r\n## 3:   4  108\r\n## 4:   6  258\r\n## 5:   8  360\r\n## 6:   6  225\r\n<\/pre>\n<pre><code class=\"r\">DT[, mean(hp), cyl]\r\n<\/code><\/pre>\n<pre>##    cyl        V1\r\n## 1:   6 122.28571\r\n## 2:   4  82.63636\r\n## 3:   8 209.21429\r\n<\/pre>\n<pre><code class=\"r\">DT[, plot(hp~mpg)]\r\n<\/code><\/pre>\n<p><img src=\"data:image\/png;base64,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\" alt=\"plot of chunk unnamed-chunk-4\" \/><\/p>\n<pre>## NULL\r\n<\/pre>\n<p>\uae54\ub054\ud558\uc8e0?<\/p>\n<h3>\uc5f4\uc774\ub984\uc744 \uac00\uc9c4 \ubcc0\uc218<\/h3>\n<p><code>DT[,j\/func]<\/code>\uc5d0\uc11c <code>j<\/code>\ub294 \uc5f4\uc744 \uc120\ud0dd\ud558\uace0, \uc5f4\uc774\ub984\uc744 \ub530\uc634\ud45c \uc5c6\uc774 \uc4f8 \uc218 \uc788\ub2e4\ub294 \uc7a5\uc810\uc774 \uc788\uc2b5\ub2c8\ub2e4.<\/p>\n<pre><code class=\"r\">DT[, cyl] %&gt;% head\r\n<\/code><\/pre>\n<pre>## [1] 6 6 4 6 8 6\r\n<\/pre>\n<p>\uccab \ubc88\uc9f8 \ubb38\uc81c\ub294 \uc5f4\uc774\ub984\uc774 \ubcc0\uc218\uc5d0 \ub4e4\uc5b4 \uc788\uc744 \ub54c\uc785\ub2c8\ub2e4.<\/p>\n<pre><code class=\"r\">cyl = c('hp', 'mpg')\r\nDT[, cyl] %&gt;% head\r\n<\/code><\/pre>\n<pre>## [1] 6 6 4 6 8 6\r\n<\/pre>\n<p>\ubcc0\uc218 <code>cyl<\/code>\uc758 <code>c('hp', 'mpg')<\/code>, \uc5f4\uc774\ub984 <code>hp<\/code>\uc640 <code>mpg<\/code>\ub97c \uc120\ud0dd\ud558\ub824\uba74 \uc5b4\ub5bb\uac8c \ud574\uc57c \ud560\uae4c\uc694?<\/p>\n<pre><code class=\"r\">DT[, ..cyl] %&gt;% head\r\n<\/code><\/pre>\n<pre>##     hp  mpg\r\n## 1: 110 21.0\r\n## 2: 110 21.0\r\n## 3:  93 22.8\r\n## 4: 110 21.4\r\n## 5: 175 18.7\r\n## 6: 105 18.1\r\n<\/pre>\n<p>\ubcf4\uc168\ub098\uc694? <code>..<\/code>\uc744 \uc501\ub2c8\ub2e4.<\/p>\n<p>\uc5f4 \uc21c\ubc88\uc774 \uc788\uc744 \ub54c\uc5d0\ub3c4 \ub9c8\ucc2c\uac00\uc9c0\uc785\ub2c8\ub2e4.<\/p>\n<pre><code class=\"r\">icols = c(3,4,5)\r\nDT[, ..icols] %&gt;% head\r\n<\/code><\/pre>\n<pre>##    disp  hp drat\r\n## 1:  160 110 3.90\r\n## 2:  160 110 3.90\r\n## 3:  108  93 3.85\r\n## 4:  258 110 3.08\r\n## 5:  360 175 3.15\r\n## 6:  225 105 2.76\r\n<\/pre>\n<h3>\uadf8\ub0e5 \ubcc0\uc218\ub85c \uc0ac\uc6a9\ud560 \ub54c<\/h3>\n<p><code>DT[,j\/func,]<\/code>\uc5d0\uc11c <code>func<\/code>\ub294 \uc5b4\ub5a4 \ud568\uc218\ub3c4 \uac00\ub2a5\ud569\ub2c8\ub2e4. \uc608\ub97c \ub4e4\uc5b4 <code>hp<\/code>\uac00 <code>100<\/code>\ubcf4\ub2e4 \ud070\uc9c0 \ud655\uc778\ud558\uace0 \uc2f6\ub2e4\uba74,<\/p>\n<pre><code class=\"r\">DT[ , hp &gt; 100]\r\n<\/code><\/pre>\n<pre>##  [1]  TRUE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE\r\n## [15]  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE\r\n## [29]  TRUE  TRUE  TRUE  TRUE\r\n<\/pre>\n<p>\ud640\uc218\ubc88\uc9f8\ub294 <code>100<\/code>, \uc9dd\uc218\ubc88\uc9f8\ub294 <code>150<\/code>\ubcf4\ub2e4 \ud070\uc9c0 \ud655\uc778\ud558\uace0\uc790 \ud55c\ub2e4\uba74,<\/p>\n<pre><code class=\"r\">DT[, hp&gt;c(100, 150)]\r\n<\/code><\/pre>\n<pre>##  [1]  TRUE FALSE FALSE FALSE  TRUE FALSE  TRUE FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE\r\n## [15]  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE FALSE FALSE FALSE\r\n## [29]  TRUE  TRUE  TRUE FALSE\r\n<\/pre>\n<p>\ub9cc\uc57d <code>c(100,150)<\/code>\uc774 \ubcc0\uc218\uc5d0 \ub2f4\uaca8 \uc788\ub2e4\uba74 \uc5b4\ub5bb\uac8c \ud574\uc57c \ud560\uae4c\uc694?<\/p>\n<pre><code class=\"r\">threshold = c(100,150)\r\nDT[, hp&gt;threshold]\r\n<\/code><\/pre>\n<pre>##  [1]  TRUE FALSE FALSE FALSE  TRUE FALSE  TRUE FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE\r\n## [15]  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE FALSE FALSE FALSE\r\n## [29]  TRUE  TRUE  TRUE FALSE\r\n<\/pre>\n<p>\uadf8\ub7f0\ub370 \uc774\ub984\uc774 \uacf5\uad50\ub86d\uac8c <code>hp<\/code>\ub77c\uba74?<\/p>\n<pre><code class=\"r\">hp = c(100,150)\r\nDT[, hp&gt;hp] #???\r\n<\/code><\/pre>\n<pre>##  [1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE\r\n## [15] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE\r\n## [29] FALSE FALSE FALSE FALSE\r\n<\/pre>\n<p>\uc774\ub7f0 \ub9d0\uc774 \ub5a0\uc624\ub985\ub2c8\ub2e4. Namespace\ub294 \uc88b\uc740 \uac83\uc774\ub2e4!?<\/p>\n<p>StackOverflow\uc758 \ud574\ubc95\uc744 \uc18c\uac1c\ud569\ub2c8\ub2e4.<\/p>\n<pre><code class=\"r\">.. &lt;- function(..., .env=sys.parent(2)) {\r\n  get(deparse(substitute(...)), env = .env)\r\n}\r\nDT[, hp &gt; ..(hp)]\r\n<\/code><\/pre>\n<pre>##  [1]  TRUE FALSE FALSE FALSE  TRUE FALSE  TRUE FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE\r\n## [15]  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE FALSE FALSE FALSE\r\n## [29]  TRUE  TRUE  TRUE FALSE\r\n<\/pre>\n<p>\uc704\uc758 \uacbd\uc6b0\uc640 \uacb0\uacfc\uac00 \uc77c\uce58\ud558\ub294\uc9c0 \ud55c \ubc88 \ud655\uc778\ud574 \ubcf4\uc2dc\uc8e0.<\/p>\n<h2>\uacb0\ub860<\/h2>\n<p>\uacb0\uacfc\uc801\uc73c\ub85c <code>hp<\/code>\ub294 \ub370\uc774\ud130 \ud14c\uc774\ube14\uc758 <strong>\uc5f4\uc774\ub984<\/strong>\uc77c \uc218\ub3c4 \uc788\uace0, \uc5f4\uc774\ub984\uc744 \ub2f4\uace0 \uc788\ub294 <strong>\uc5f4\uc774\ub984 \ubcc0\uc218<\/strong>\uc77c \uc218\ub3c4 \uc788\uace0, \uc544\ub2c8\uba74 \ub370\uc774\ud130 \ud14c\uc774\ube14\uc774 \uc874\uc7ac\ud558\ub294 \ud658\uacbd(\uc774\ub97c <strong>\ubd80\ubaa8 \ud658\uacbd<\/strong>\uc774\ub77c\uace0 \ud569\uc2dc\ub2e4)<strong>\uc758 \uc5b4\ub5a4 \ubcc0\uc218<\/strong>\uc77c \uc218\ub3c4 \uc788\uc2b5\ub2c8\ub2e4.<\/p>\n<pre><code class=\"r\">DT[, x]     # \uc5f4\uc774\ub984\r\nDT[, ..x]   # \uc5f4\uc774\ub984 \ubcc0\uc218\r\nDT[, ..(x)] # \ubd80\ubaa8 \ud658\uacbd\uc758 \ubcc0\uc218\r\n<\/code><\/pre>\n<p>\uc0ac\uc2e4 <code>DT[, ..x]<\/code>\uc5d0\uc11c <code>x<\/code>\ub3c4 \ubd80\ubaa8 \ud658\uacbd\uc758 \ubcc0\uc218\uc774\uae34 \ud569\ub2c8\ub2e4\ub9cc, <strong>\uc5f4\uc774\ub984<\/strong> \ub610\ub294 <strong>\uc5f4\uc21c\ubc88<\/strong>\uc744 \ub098\ud0c0\ub0b4\ub294 \uac83\uc73c\ub85c \ud574\uc11d\ub41c\ub2e4\ub294 \uc810\uc5d0\uc11c \ubd80\ubaa8 \ud658\uacbd \ubcc0\uc218\uc640 \ub2e4\ub974\uaca0\uc2b5\ub2c8\ub2e4. \ud568\uc218 <code>..()<\/code>\ub294 \ub2e4\uc74c\uacfc \uac19\uc774 \ubbf8\ub9ac \uc815\uc758\ud574 \ub450\uc5b4\uc57c \ud55c\ub2e4\ub294 \uc810\uc744 \uc78a\uc9c0 \ub9c8\uc138\uc694.<\/p>\n<pre><code class=\"r\">.. &lt;- function(..., .env=sys.parent(2)) {\r\n  get(deparse(substitute(...)), env = .env)\r\n}\r\n<\/code><\/pre>\n<h2>\ubd80\ub85d<\/h2>\n<p>\ub2e4\uc74c\uc758 \ub450 \uc608\uc5d0\uc11c <code>4<\/code>\ub294 \uc5b4\ub5bb\uac8c \ub2e4\ub978\uc9c0 \uc124\uba85\ud574\ubcf4\uc138\uc694.<\/p>\n<pre><code class=\"r\">DT[, 4] %&gt;% head\r\n<\/code><\/pre>\n<pre>##     hp\r\n## 1: 110\r\n## 2: 110\r\n## 3:  93\r\n## 4: 110\r\n## 5: 175\r\n## 6: 105\r\n<\/pre>\n<pre><code class=\"r\">DT[, cyl&gt;4]\r\n<\/code><\/pre>\n<pre>##  [1]  TRUE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE\r\n## [15]  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE\r\n## [29]  TRUE  TRUE  TRUE FALSE\r\n<\/pre>\n<p>\uadf8\ub807\ub2e4\uba74 \ub2e4\uc74c\uc758 \uacb0\uacfc\ub294 \uc5b4\ub5bb\uac8c \ub420\uae4c\uc694?<\/p>\n<pre><code class=\"r\">DT[, (4)]\r\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>R data.table R shiny Korea meetup\uc5d0\uc11c R \ub370\uc774\ud130 \ud14c\uc774\ube14\uc744 \uc18c\uac1c\ud558\ub294 \ubc1c\ud45c\ub97c \ud588\uc2b5\ub2c8\ub2e4. CRUD(Create\/Read\/Update\/Delete) CRUD \uc815\ub3c4\ub294 DT[i\/filter, j\/summarise, by] \uc815\ub3c4\uc5d0\uc11c \ubaa8\ub450 \ub05d\ub0bc \uc218 \uc788\uc2b5\ub2c8\ub2e4. DT[i, j\/summarise\/func, by]\uc5d0\uc11c j\/summarise\/func \ubd80\ubd84\uc744 \ubd05\uc2dc\ub2e4. \uc774 \ubd80\ubd84\uc5d0\uc11c \ub370\uc774\ud130\ud14c\uc774\ube14\uc758 \uc5f4(column)\uc744 \uc120\ud0dd\ud558\uac70\ub098, \uc5f4\uc744 \uc694\uc57d\ud558\ub294 \ud568\uc218\ub97c \uc801\uc6a9\ud558\uac70\ub098, \uc77c\ubc18\uc801\uc778 \ud568\uc218\ub97c \uc801\uc6a9\ud560 \uc218 \uc788\uc2b5\ub2c8\ub2e4. \uc5f4 : DT[, c(2,3)] \uc694\uc57d : DT[, mean(hp), cyl] \uc77c\ubc18\uc801\uc778 \ud568\uc218 : [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":968,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[28,207],"tags":[183,466,465],"jetpack_featured_media_url":"http:\/\/ds.sumeun.org\/wp-content\/uploads\/2019\/03\/datatable.png","_links":{"self":[{"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=\/wp\/v2\/posts\/2215"}],"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=2215"}],"version-history":[{"count":3,"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=\/wp\/v2\/posts\/2215\/revisions"}],"predecessor-version":[{"id":2218,"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=\/wp\/v2\/posts\/2215\/revisions\/2218"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=\/wp\/v2\/media\/968"}],"wp:attachment":[{"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2215"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2215"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/ds.sumeun.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2215"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}