1-import-data/readr-package.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "Downloading GitHub repo tidyverse/readr@master\n",
      "from URL https://api.github.com/repos/tidyverse/readr/zipball/master\n",
      "Installing readr\n",
      "Installing BH\n",
      "'/usr/lib/R/bin/R' --no-site-file --no-environ --no-save --no-restore --quiet  \\\n",
      "  CMD INSTALL '/tmp/Rtmpwi2iUG/devtools2cce121ca058/BH'  \\\n",
      "  --library='/home/duyetdev/R/x86_64-pc-linux-gnu-library/3.3'  \\\n",
      "  --install-tests \n",
      "\n",
      "Installing R6\n",
      "'/usr/lib/R/bin/R' --no-site-file --no-environ --no-save --no-restore --quiet  \\\n",
      "  CMD INSTALL '/tmp/Rtmpwi2iUG/devtools2cce75f672ce/R6'  \\\n",
      "  --library='/home/duyetdev/R/x86_64-pc-linux-gnu-library/3.3'  \\\n",
      "  --install-tests \n",
      "\n",
      "Installing Rcpp\n",
      "'/usr/lib/R/bin/R' --no-site-file --no-environ --no-save --no-restore --quiet  \\\n",
      "  CMD INSTALL '/tmp/Rtmpwi2iUG/devtools2cce21e72fd4/Rcpp'  \\\n",
      "  --library='/home/duyetdev/R/x86_64-pc-linux-gnu-library/3.3'  \\\n",
      "  --install-tests \n",
      "\n",
      "'/usr/lib/R/bin/R' --no-site-file --no-environ --no-save --no-restore --quiet  \\\n",
      "  CMD INSTALL '/tmp/Rtmpwi2iUG/devtools2cce723a220d/tidyverse-readr-70b2a3c'  \\\n",
      "  --library='/home/duyetdev/R/x86_64-pc-linux-gnu-library/3.3'  \\\n",
      "  --install-tests \n",
      "\n"
     ]
    }
   ],
   "source": [
    "# Cài đặt `readr` package \n",
    "devtools::install_github(\"tidyverse/readr\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "# Load the readr package\n",
    "library(readr)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# read_csv\n",
    "\n",
    "Đọc file csv"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "Parsed with column specification:\n",
      "cols(\n",
      "  area = col_integer(),\n",
      "  temp = col_integer(),\n",
      "  size = col_integer(),\n",
      "  storage = col_integer(),\n",
      "  method = col_integer(),\n",
      "  texture = col_double(),\n",
      "  flavor = col_double(),\n",
      "  moistness = col_double()\n",
      ")\n"
     ]
    }
   ],
   "source": [
    "# Import potatoes.csv with read_csv(): potatoes\n",
    "potatoes <- read_csv('potatoes.csv')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "data": {
      "text/html": [
       "<table>\n",
       "<thead><tr><th scope=col>area</th><th scope=col>temp</th><th scope=col>size</th><th scope=col>storage</th><th scope=col>method</th><th scope=col>texture</th><th scope=col>flavor</th><th scope=col>moistness</th></tr></thead>\n",
       "<tbody>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>2.9</td><td>3.2</td><td>3.0</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>2  </td><td>2.3</td><td>2.5</td><td>2.6</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>3  </td><td>2.5</td><td>2.8</td><td>2.8</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>4  </td><td>2.1</td><td>2.9</td><td>2.4</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>5  </td><td>1.9</td><td>2.8</td><td>2.2</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>2  </td><td>1  </td><td>1.8</td><td>3.0</td><td>1.7</td></tr>\n",
       "</tbody>\n",
       "</table>\n"
      ],
      "text/latex": [
       "\\begin{tabular}{r|llllllll}\n",
       " area & temp & size & storage & method & texture & flavor & moistness\\\\\n",
       "\\hline\n",
       "\t 1   & 1   & 1   & 1   & 1   & 2.9 & 3.2 & 3.0\\\\\n",
       "\t 1   & 1   & 1   & 1   & 2   & 2.3 & 2.5 & 2.6\\\\\n",
       "\t 1   & 1   & 1   & 1   & 3   & 2.5 & 2.8 & 2.8\\\\\n",
       "\t 1   & 1   & 1   & 1   & 4   & 2.1 & 2.9 & 2.4\\\\\n",
       "\t 1   & 1   & 1   & 1   & 5   & 1.9 & 2.8 & 2.2\\\\\n",
       "\t 1   & 1   & 1   & 2   & 1   & 1.8 & 3.0 & 1.7\\\\\n",
       "\\end{tabular}\n"
      ],
      "text/markdown": [
       "\n",
       "area | temp | size | storage | method | texture | flavor | moistness | \n",
       "|---|---|---|---|---|---|\n",
       "| 1   | 1   | 1   | 1   | 1   | 2.9 | 3.2 | 3.0 | \n",
       "| 1   | 1   | 1   | 1   | 2   | 2.3 | 2.5 | 2.6 | \n",
       "| 1   | 1   | 1   | 1   | 3   | 2.5 | 2.8 | 2.8 | \n",
       "| 1   | 1   | 1   | 1   | 4   | 2.1 | 2.9 | 2.4 | \n",
       "| 1   | 1   | 1   | 1   | 5   | 1.9 | 2.8 | 2.2 | \n",
       "| 1   | 1   | 1   | 2   | 1   | 1.8 | 3.0 | 1.7 | \n",
       "\n",
       "\n"
      ],
      "text/plain": [
       "  area temp size storage method texture flavor moistness\n",
       "1 1    1    1    1       1      2.9     3.2    3.0      \n",
       "2 1    1    1    1       2      2.3     2.5    2.6      \n",
       "3 1    1    1    1       3      2.5     2.8    2.8      \n",
       "4 1    1    1    1       4      2.1     2.9    2.4      \n",
       "5 1    1    1    1       5      1.9     2.8    2.2      \n",
       "6 1    1    1    2       1      1.8     3.0    1.7      "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "head(potatoes)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# read_tsv\n",
    "\n",
    "Đọc file tsv, các cột phân cách nhau bằng dấu tab \\t \n",
    "\n",
    "Đọc file [potatoes.txt](potatoes.txt) có nội dung như sau:\n",
    "\n",
    "```\n",
    "1\t1\t1\t1\t1\t2.9\t3.2\t3.0\n",
    "1\t1\t1\t1\t2\t2.3\t2.5\t2.6\n",
    "1\t1\t1\t1\t3\t2.5\t2.8\t2.8\n",
    "1\t1\t1\t1\t4\t2.1\t2.9\t2.4\n",
    "1\t1\t1\t1\t5\t1.9\t2.8\t2.2\n",
    "1\t1\t1\t2\t1\t1.8\t3.0\t1.7\n",
    "1\t1\t1\t2\t2\t2.6\t3.1\t2.4\n",
    "...\n",
    "```"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "Parsed with column specification:\n",
      "cols(\n",
      "  area = col_integer(),\n",
      "  temp = col_integer(),\n",
      "  size = col_integer(),\n",
      "  storage = col_integer(),\n",
      "  method = col_integer(),\n",
      "  texture = col_double(),\n",
      "  flavor = col_double(),\n",
      "  moistness = col_double()\n",
      ")\n"
     ]
    },
    {
     "data": {
      "text/html": [
       "<table>\n",
       "<thead><tr><th scope=col>area</th><th scope=col>temp</th><th scope=col>size</th><th scope=col>storage</th><th scope=col>method</th><th scope=col>texture</th><th scope=col>flavor</th><th scope=col>moistness</th></tr></thead>\n",
       "<tbody>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>2.9</td><td>3.2</td><td>3.0</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>2  </td><td>2.3</td><td>2.5</td><td>2.6</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>3  </td><td>2.5</td><td>2.8</td><td>2.8</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>4  </td><td>2.1</td><td>2.9</td><td>2.4</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>5  </td><td>1.9</td><td>2.8</td><td>2.2</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>2  </td><td>1  </td><td>1.8</td><td>3.0</td><td>1.7</td></tr>\n",
       "</tbody>\n",
       "</table>\n"
      ],
      "text/latex": [
       "\\begin{tabular}{r|llllllll}\n",
       " area & temp & size & storage & method & texture & flavor & moistness\\\\\n",
       "\\hline\n",
       "\t 1   & 1   & 1   & 1   & 1   & 2.9 & 3.2 & 3.0\\\\\n",
       "\t 1   & 1   & 1   & 1   & 2   & 2.3 & 2.5 & 2.6\\\\\n",
       "\t 1   & 1   & 1   & 1   & 3   & 2.5 & 2.8 & 2.8\\\\\n",
       "\t 1   & 1   & 1   & 1   & 4   & 2.1 & 2.9 & 2.4\\\\\n",
       "\t 1   & 1   & 1   & 1   & 5   & 1.9 & 2.8 & 2.2\\\\\n",
       "\t 1   & 1   & 1   & 2   & 1   & 1.8 & 3.0 & 1.7\\\\\n",
       "\\end{tabular}\n"
      ],
      "text/markdown": [
       "\n",
       "area | temp | size | storage | method | texture | flavor | moistness | \n",
       "|---|---|---|---|---|---|\n",
       "| 1   | 1   | 1   | 1   | 1   | 2.9 | 3.2 | 3.0 | \n",
       "| 1   | 1   | 1   | 1   | 2   | 2.3 | 2.5 | 2.6 | \n",
       "| 1   | 1   | 1   | 1   | 3   | 2.5 | 2.8 | 2.8 | \n",
       "| 1   | 1   | 1   | 1   | 4   | 2.1 | 2.9 | 2.4 | \n",
       "| 1   | 1   | 1   | 1   | 5   | 1.9 | 2.8 | 2.2 | \n",
       "| 1   | 1   | 1   | 2   | 1   | 1.8 | 3.0 | 1.7 | \n",
       "\n",
       "\n"
      ],
      "text/plain": [
       "  area temp size storage method texture flavor moistness\n",
       "1 1    1    1    1       1      2.9     3.2    3.0      \n",
       "2 1    1    1    1       2      2.3     2.5    2.6      \n",
       "3 1    1    1    1       3      2.5     2.8    2.8      \n",
       "4 1    1    1    1       4      2.1     2.9    2.4      \n",
       "5 1    1    1    1       5      1.9     2.8    2.2      \n",
       "6 1    1    1    2       1      1.8     3.0    1.7      "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "# Column names\n",
    "properties <- c(\"area\", \"temp\", \"size\", \"storage\", \"method\",\n",
    "                \"texture\", \"flavor\", \"moistness\")\n",
    "# read_tsv\n",
    "potatoes <- read_tsv('potatoes.txt', col_names=properties)\n",
    "\n",
    "# head of dataframe\n",
    "head(potatoes)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# read_delim()\n",
    "\n",
    "Tương tự `read.delim()` hay `read.table()` của `utils` package. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "Parsed with column specification:\n",
      "cols(\n",
      "  area = col_integer(),\n",
      "  temp = col_integer(),\n",
      "  size = col_integer(),\n",
      "  storage = col_integer(),\n",
      "  method = col_integer(),\n",
      "  texture = col_double(),\n",
      "  flavor = col_double(),\n",
      "  moistness = col_double()\n",
      ")\n"
     ]
    },
    {
     "data": {
      "text/html": [
       "<table>\n",
       "<thead><tr><th scope=col>area</th><th scope=col>temp</th><th scope=col>size</th><th scope=col>storage</th><th scope=col>method</th><th scope=col>texture</th><th scope=col>flavor</th><th scope=col>moistness</th></tr></thead>\n",
       "<tbody>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>2.9</td><td>3.2</td><td>3.0</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>2  </td><td>2.3</td><td>2.5</td><td>2.6</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>3  </td><td>2.5</td><td>2.8</td><td>2.8</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>4  </td><td>2.1</td><td>2.9</td><td>2.4</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>1  </td><td>5  </td><td>1.9</td><td>2.8</td><td>2.2</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>2  </td><td>1  </td><td>1.8</td><td>3.0</td><td>1.7</td></tr>\n",
       "</tbody>\n",
       "</table>\n"
      ],
      "text/latex": [
       "\\begin{tabular}{r|llllllll}\n",
       " area & temp & size & storage & method & texture & flavor & moistness\\\\\n",
       "\\hline\n",
       "\t 1   & 1   & 1   & 1   & 1   & 2.9 & 3.2 & 3.0\\\\\n",
       "\t 1   & 1   & 1   & 1   & 2   & 2.3 & 2.5 & 2.6\\\\\n",
       "\t 1   & 1   & 1   & 1   & 3   & 2.5 & 2.8 & 2.8\\\\\n",
       "\t 1   & 1   & 1   & 1   & 4   & 2.1 & 2.9 & 2.4\\\\\n",
       "\t 1   & 1   & 1   & 1   & 5   & 1.9 & 2.8 & 2.2\\\\\n",
       "\t 1   & 1   & 1   & 2   & 1   & 1.8 & 3.0 & 1.7\\\\\n",
       "\\end{tabular}\n"
      ],
      "text/markdown": [
       "\n",
       "area | temp | size | storage | method | texture | flavor | moistness | \n",
       "|---|---|---|---|---|---|\n",
       "| 1   | 1   | 1   | 1   | 1   | 2.9 | 3.2 | 3.0 | \n",
       "| 1   | 1   | 1   | 1   | 2   | 2.3 | 2.5 | 2.6 | \n",
       "| 1   | 1   | 1   | 1   | 3   | 2.5 | 2.8 | 2.8 | \n",
       "| 1   | 1   | 1   | 1   | 4   | 2.1 | 2.9 | 2.4 | \n",
       "| 1   | 1   | 1   | 1   | 5   | 1.9 | 2.8 | 2.2 | \n",
       "| 1   | 1   | 1   | 2   | 1   | 1.8 | 3.0 | 1.7 | \n",
       "\n",
       "\n"
      ],
      "text/plain": [
       "  area temp size storage method texture flavor moistness\n",
       "1 1    1    1    1       1      2.9     3.2    3.0      \n",
       "2 1    1    1    1       2      2.3     2.5    2.6      \n",
       "3 1    1    1    1       3      2.5     2.8    2.8      \n",
       "4 1    1    1    1       4      2.1     2.9    2.4      \n",
       "5 1    1    1    1       5      1.9     2.8    2.2      \n",
       "6 1    1    1    2       1      1.8     3.0    1.7      "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "properties <- c(\"area\", \"temp\", \"size\", \"storage\", \"method\",\n",
    "                \"texture\", \"flavor\", \"moistness\")\n",
    "potatoes <- read_delim('potatoes.txt', col_names=properties, delim='\\t')\n",
    "\n",
    "# head of dataframe \n",
    "head(potatoes)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# skip and n_max\n",
    "\n",
    "`skip` bỏ qua n dòng đầu tiên. `n_max` khai báo số dòng tối đa. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "Parsed with column specification:\n",
      "cols(\n",
      "  area = col_integer(),\n",
      "  temp = col_integer(),\n",
      "  size = col_integer(),\n",
      "  storage = col_integer(),\n",
      "  method = col_integer(),\n",
      "  texture = col_double(),\n",
      "  flavor = col_double(),\n",
      "  moistness = col_double()\n",
      ")\n"
     ]
    },
    {
     "data": {
      "text/html": [
       "<table>\n",
       "<thead><tr><th scope=col>area</th><th scope=col>temp</th><th scope=col>size</th><th scope=col>storage</th><th scope=col>method</th><th scope=col>texture</th><th scope=col>flavor</th><th scope=col>moistness</th></tr></thead>\n",
       "<tbody>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>2  </td><td>1  </td><td>1.8</td><td>3.0</td><td>1.7</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>2  </td><td>2  </td><td>2.6</td><td>3.1</td><td>2.4</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>2  </td><td>3  </td><td>3.0</td><td>3.0</td><td>2.9</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>2  </td><td>4  </td><td>2.2</td><td>3.2</td><td>2.5</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>2  </td><td>5  </td><td>2.0</td><td>2.8</td><td>1.9</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>3  </td><td>1  </td><td>1.8</td><td>2.6</td><td>1.5</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>3  </td><td>2  </td><td>2.0</td><td>2.8</td><td>1.9</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>3  </td><td>3  </td><td>2.6</td><td>2.6</td><td>2.6</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>3  </td><td>4  </td><td>2.1</td><td>3.2</td><td>2.1</td></tr>\n",
       "\t<tr><td>1  </td><td>1  </td><td>1  </td><td>3  </td><td>5  </td><td>2.5</td><td>3.0</td><td>2.1</td></tr>\n",
       "</tbody>\n",
       "</table>\n"
      ],
      "text/latex": [
       "\\begin{tabular}{r|llllllll}\n",
       " area & temp & size & storage & method & texture & flavor & moistness\\\\\n",
       "\\hline\n",
       "\t 1   & 1   & 1   & 2   & 1   & 1.8 & 3.0 & 1.7\\\\\n",
       "\t 1   & 1   & 1   & 2   & 2   & 2.6 & 3.1 & 2.4\\\\\n",
       "\t 1   & 1   & 1   & 2   & 3   & 3.0 & 3.0 & 2.9\\\\\n",
       "\t 1   & 1   & 1   & 2   & 4   & 2.2 & 3.2 & 2.5\\\\\n",
       "\t 1   & 1   & 1   & 2   & 5   & 2.0 & 2.8 & 1.9\\\\\n",
       "\t 1   & 1   & 1   & 3   & 1   & 1.8 & 2.6 & 1.5\\\\\n",
       "\t 1   & 1   & 1   & 3   & 2   & 2.0 & 2.8 & 1.9\\\\\n",
       "\t 1   & 1   & 1   & 3   & 3   & 2.6 & 2.6 & 2.6\\\\\n",
       "\t 1   & 1   & 1   & 3   & 4   & 2.1 & 3.2 & 2.1\\\\\n",
       "\t 1   & 1   & 1   & 3   & 5   & 2.5 & 3.0 & 2.1\\\\\n",
       "\\end{tabular}\n"
      ],
      "text/markdown": [
       "\n",
       "area | temp | size | storage | method | texture | flavor | moistness | \n",
       "|---|---|---|---|---|---|---|---|---|---|\n",
       "| 1   | 1   | 1   | 2   | 1   | 1.8 | 3.0 | 1.7 | \n",
       "| 1   | 1   | 1   | 2   | 2   | 2.6 | 3.1 | 2.4 | \n",
       "| 1   | 1   | 1   | 2   | 3   | 3.0 | 3.0 | 2.9 | \n",
       "| 1   | 1   | 1   | 2   | 4   | 2.2 | 3.2 | 2.5 | \n",
       "| 1   | 1   | 1   | 2   | 5   | 2.0 | 2.8 | 1.9 | \n",
       "| 1   | 1   | 1   | 3   | 1   | 1.8 | 2.6 | 1.5 | \n",
       "| 1   | 1   | 1   | 3   | 2   | 2.0 | 2.8 | 1.9 | \n",
       "| 1   | 1   | 1   | 3   | 3   | 2.6 | 2.6 | 2.6 | \n",
       "| 1   | 1   | 1   | 3   | 4   | 2.1 | 3.2 | 2.1 | \n",
       "| 1   | 1   | 1   | 3   | 5   | 2.5 | 3.0 | 2.1 | \n",
       "\n",
       "\n"
      ],
      "text/plain": [
       "   area temp size storage method texture flavor moistness\n",
       "1  1    1    1    2       1      1.8     3.0    1.7      \n",
       "2  1    1    1    2       2      2.6     3.1    2.4      \n",
       "3  1    1    1    2       3      3.0     3.0    2.9      \n",
       "4  1    1    1    2       4      2.2     3.2    2.5      \n",
       "5  1    1    1    2       5      2.0     2.8    1.9      \n",
       "6  1    1    1    3       1      1.8     2.6    1.5      \n",
       "7  1    1    1    3       2      2.0     2.8    1.9      \n",
       "8  1    1    1    3       3      2.6     2.6    2.6      \n",
       "9  1    1    1    3       4      2.1     3.2    2.1      \n",
       "10 1    1    1    3       5      2.5     3.0    2.1      "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "# Lấy 10 dòng, kể từ dòng thứ 5\n",
    "potatoes_fragment <- read_tsv(\"potatoes.txt\", skip = 5, n_max = 10, col_names = properties)\n",
    "\n",
    "potatoes_fragment"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# col_types\n",
    "\n",
    "`col_types` quy định loại dữ liệu nào sẽ đc parse vào data.frame, nếu để mặc định `col_types = NULL`, \n",
    "`readr` sẽ tìm ra loại dữ liệu phù hợp nhất. \n",
    "\n",
    "Các loại dữ liệu: `c`haracter, `d`ouble, `i`nteger and `l`ogical. `_` bỏ qua cột đó. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "# Column names\n",
    "properties <- c(\"area\", \"temp\", \"size\", \"storage\", \"method\",\n",
    "                \"texture\", \"flavor\", \"moistness\")\n",
    "\n",
    "# Import all data, but force all columns to be character: potatoes_char\n",
    "potatoes_char <- read_tsv(\"potatoes.txt\", col_types = \"iiiiiddd\", col_names = properties)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Classes ‘tbl_df’, ‘tbl’ and 'data.frame':\t160 obs. of  8 variables:\n",
      " $ area     : int  1 1 1 1 1 1 1 1 1 1 ...\n",
      " $ temp     : int  1 1 1 1 1 1 1 1 1 1 ...\n",
      " $ size     : int  1 1 1 1 1 1 1 1 1 1 ...\n",
      " $ storage  : int  1 1 1 1 1 2 2 2 2 2 ...\n",
      " $ method   : int  1 2 3 4 5 1 2 3 4 5 ...\n",
      " $ texture  : num  2.9 2.3 2.5 2.1 1.9 1.8 2.6 3 2.2 2 ...\n",
      " $ flavor   : num  3.2 2.5 2.8 2.9 2.8 3 3.1 3 3.2 2.8 ...\n",
      " $ moistness: num  3 2.6 2.8 2.4 2.2 1.7 2.4 2.9 2.5 1.9 ...\n",
      " - attr(*, \"spec\")=List of 2\n",
      "  ..$ cols   :List of 8\n",
      "  .. ..$ area     : list()\n",
      "  .. .. ..- attr(*, \"class\")= chr  \"collector_integer\" \"collector\"\n",
      "  .. ..$ temp     : list()\n",
      "  .. .. ..- attr(*, \"class\")= chr  \"collector_integer\" \"collector\"\n",
      "  .. ..$ size     : list()\n",
      "  .. .. ..- attr(*, \"class\")= chr  \"collector_integer\" \"collector\"\n",
      "  .. ..$ storage  : list()\n",
      "  .. .. ..- attr(*, \"class\")= chr  \"collector_integer\" \"collector\"\n",
      "  .. ..$ method   : list()\n",
      "  .. .. ..- attr(*, \"class\")= chr  \"collector_integer\" \"collector\"\n",
      "  .. ..$ texture  : list()\n",
      "  .. .. ..- attr(*, \"class\")= chr  \"collector_double\" \"collector\"\n",
      "  .. ..$ flavor   : list()\n",
      "  .. .. ..- attr(*, \"class\")= chr  \"collector_double\" \"collector\"\n",
      "  .. ..$ moistness: list()\n",
      "  .. .. ..- attr(*, \"class\")= chr  \"collector_double\" \"collector\"\n",
      "  ..$ default: list()\n",
      "  .. ..- attr(*, \"class\")= chr  \"collector_guess\" \"collector\"\n",
      "  ..- attr(*, \"class\")= chr \"col_spec\"\n"
     ]
    }
   ],
   "source": [
    "str(potatoes_char)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": []
  }
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