Lecture17.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "In this notebook, we will continue discussing regular expression related tools:\n",
    "\n",
    "* [Grouped matches](#Grouped-matches)\n",
    "* [Replacing matches](#Replacing-matches)\n",
    "* [Splitting](#Splitting)\n",
    "* [Find matches](#Find-matches)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Grouped matches"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "── \u001b[1mAttaching packages\u001b[22m ─────────────────────────────────────── tidyverse 1.3.0 ──\n",
      "\n",
      "\u001b[32m✔\u001b[39m \u001b[34mggplot2\u001b[39m 3.2.1     \u001b[32m✔\u001b[39m \u001b[34mpurrr  \u001b[39m 0.3.3\n",
      "\u001b[32m✔\u001b[39m \u001b[34mtibble \u001b[39m 2.1.3     \u001b[32m✔\u001b[39m \u001b[34mdplyr  \u001b[39m 0.8.4\n",
      "\u001b[32m✔\u001b[39m \u001b[34mtidyr  \u001b[39m 1.0.2     \u001b[32m✔\u001b[39m \u001b[34mstringr\u001b[39m 1.4.0\n",
      "\u001b[32m✔\u001b[39m \u001b[34mreadr  \u001b[39m 1.3.1     \u001b[32m✔\u001b[39m \u001b[34mforcats\u001b[39m 0.4.0\n",
      "\n",
      "── \u001b[1mConflicts\u001b[22m ────────────────────────────────────────── tidyverse_conflicts() ──\n",
      "\u001b[31m✖\u001b[39m \u001b[34mdplyr\u001b[39m::\u001b[32mfilter()\u001b[39m masks \u001b[34mstats\u001b[39m::filter()\n",
      "\u001b[31m✖\u001b[39m \u001b[34mdplyr\u001b[39m::\u001b[32mlag()\u001b[39m    masks \u001b[34mstats\u001b[39m::lag()\n",
      "\n"
     ]
    }
   ],
   "source": [
    "library(tidyverse)\n",
    "library(stringr)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<ol class=list-inline>\n",
       "\t<li>'bring'</li>\n",
       "\t<li>'during'</li>\n",
       "\t<li>'evening'</li>\n",
       "\t<li>'king'</li>\n",
       "\t<li>'meaning'</li>\n",
       "\t<li>'morning'</li>\n",
       "\t<li>'ring'</li>\n",
       "\t<li>'sing'</li>\n",
       "\t<li>'thing'</li>\n",
       "</ol>\n"
      ],
      "text/latex": [
       "\\begin{enumerate*}\n",
       "\\item 'bring'\n",
       "\\item 'during'\n",
       "\\item 'evening'\n",
       "\\item 'king'\n",
       "\\item 'meaning'\n",
       "\\item 'morning'\n",
       "\\item 'ring'\n",
       "\\item 'sing'\n",
       "\\item 'thing'\n",
       "\\end{enumerate*}\n"
      ],
      "text/markdown": [
       "1. 'bring'\n",
       "2. 'during'\n",
       "3. 'evening'\n",
       "4. 'king'\n",
       "5. 'meaning'\n",
       "6. 'morning'\n",
       "7. 'ring'\n",
       "8. 'sing'\n",
       "9. 'thing'\n",
       "\n",
       "\n"
      ],
      "text/plain": [
       "[1] \"bring\"   \"during\"  \"evening\" \"king\"    \"meaning\" \"morning\" \"ring\"   \n",
       "[8] \"sing\"    \"thing\"  "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "regex <- \"^(.*)(ing)$\"\n",
    "(ing_words <- str_subset(words, regex))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<ol class=list-inline>\n",
       "\t<li>'bring'</li>\n",
       "\t<li>'during'</li>\n",
       "\t<li>'evening'</li>\n",
       "\t<li>'king'</li>\n",
       "\t<li>'meaning'</li>\n",
       "\t<li>'morning'</li>\n",
       "\t<li>'ring'</li>\n",
       "\t<li>'sing'</li>\n",
       "\t<li>'thing'</li>\n",
       "</ol>\n"
      ],
      "text/latex": [
       "\\begin{enumerate*}\n",
       "\\item 'bring'\n",
       "\\item 'during'\n",
       "\\item 'evening'\n",
       "\\item 'king'\n",
       "\\item 'meaning'\n",
       "\\item 'morning'\n",
       "\\item 'ring'\n",
       "\\item 'sing'\n",
       "\\item 'thing'\n",
       "\\end{enumerate*}\n"
      ],
      "text/markdown": [
       "1. 'bring'\n",
       "2. 'during'\n",
       "3. 'evening'\n",
       "4. 'king'\n",
       "5. 'meaning'\n",
       "6. 'morning'\n",
       "7. 'ring'\n",
       "8. 'sing'\n",
       "9. 'thing'\n",
       "\n",
       "\n"
      ],
      "text/plain": [
       "[1] \"bring\"   \"during\"  \"evening\" \"king\"    \"meaning\" \"morning\" \"ring\"   \n",
       "[8] \"sing\"    \"thing\"  "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "ing_words %>%\n",
    "    str_extract(regex)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<table>\n",
       "<caption>A matrix: 9 × 3 of type chr</caption>\n",
       "<tbody>\n",
       "\t<tr><td>bring  </td><td>br  </td><td>ing</td></tr>\n",
       "\t<tr><td>during </td><td>dur </td><td>ing</td></tr>\n",
       "\t<tr><td>evening</td><td>even</td><td>ing</td></tr>\n",
       "\t<tr><td>king   </td><td>k   </td><td>ing</td></tr>\n",
       "\t<tr><td>meaning</td><td>mean</td><td>ing</td></tr>\n",
       "\t<tr><td>morning</td><td>morn</td><td>ing</td></tr>\n",
       "\t<tr><td>ring   </td><td>r   </td><td>ing</td></tr>\n",
       "\t<tr><td>sing   </td><td>s   </td><td>ing</td></tr>\n",
       "\t<tr><td>thing  </td><td>th  </td><td>ing</td></tr>\n",
       "</tbody>\n",
       "</table>\n"
      ],
      "text/latex": [
       "A matrix: 9 × 3 of type chr\n",
       "\\begin{tabular}{lll}\n",
       "\t bring   & br   & ing\\\\\n",
       "\t during  & dur  & ing\\\\\n",
       "\t evening & even & ing\\\\\n",
       "\t king    & k    & ing\\\\\n",
       "\t meaning & mean & ing\\\\\n",
       "\t morning & morn & ing\\\\\n",
       "\t ring    & r    & ing\\\\\n",
       "\t sing    & s    & ing\\\\\n",
       "\t thing   & th   & ing\\\\\n",
       "\\end{tabular}\n"
      ],
      "text/markdown": [
       "\n",
       "A matrix: 9 × 3 of type chr\n",
       "\n",
       "| bring   | br   | ing |\n",
       "| during  | dur  | ing |\n",
       "| evening | even | ing |\n",
       "| king    | k    | ing |\n",
       "| meaning | mean | ing |\n",
       "| morning | morn | ing |\n",
       "| ring    | r    | ing |\n",
       "| sing    | s    | ing |\n",
       "| thing   | th   | ing |\n",
       "\n"
      ],
      "text/plain": [
       "      [,1]    [,2] [,3]\n",
       " [1,] bring   br   ing \n",
       " [2,] during  dur  ing \n",
       " [3,] evening even ing \n",
       " [4,] king    k    ing \n",
       " [5,] meaning mean ing \n",
       " [6,] morning morn ing \n",
       " [7,] ring    r    ing \n",
       " [8,] sing    s    ing \n",
       " [9,] thing   th   ing "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "ing_words %>%\n",
    "    str_match(regex)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Replacing matches"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<ol class=list-inline>\n",
       "\t<li>'bottom'</li>\n",
       "\t<li>'doctor'</li>\n",
       "\t<li>'history'</li>\n",
       "\t<li>'into'</li>\n",
       "\t<li>'photograph'</li>\n",
       "\t<li>'stop'</li>\n",
       "\t<li>'story'</li>\n",
       "\t<li>'to'</li>\n",
       "\t<li>'today'</li>\n",
       "\t<li>'together'</li>\n",
       "\t<li>'tomorrow'</li>\n",
       "\t<li>'tonight'</li>\n",
       "\t<li>'too'</li>\n",
       "\t<li>'top'</li>\n",
       "\t<li>'total'</li>\n",
       "\t<li>'touch'</li>\n",
       "\t<li>'toward'</li>\n",
       "\t<li>'town'</li>\n",
       "</ol>\n"
      ],
      "text/latex": [
       "\\begin{enumerate*}\n",
       "\\item 'bottom'\n",
       "\\item 'doctor'\n",
       "\\item 'history'\n",
       "\\item 'into'\n",
       "\\item 'photograph'\n",
       "\\item 'stop'\n",
       "\\item 'story'\n",
       "\\item 'to'\n",
       "\\item 'today'\n",
       "\\item 'together'\n",
       "\\item 'tomorrow'\n",
       "\\item 'tonight'\n",
       "\\item 'too'\n",
       "\\item 'top'\n",
       "\\item 'total'\n",
       "\\item 'touch'\n",
       "\\item 'toward'\n",
       "\\item 'town'\n",
       "\\end{enumerate*}\n"
      ],
      "text/markdown": [
       "1. 'bottom'\n",
       "2. 'doctor'\n",
       "3. 'history'\n",
       "4. 'into'\n",
       "5. 'photograph'\n",
       "6. 'stop'\n",
       "7. 'story'\n",
       "8. 'to'\n",
       "9. 'today'\n",
       "10. 'together'\n",
       "11. 'tomorrow'\n",
       "12. 'tonight'\n",
       "13. 'too'\n",
       "14. 'top'\n",
       "15. 'total'\n",
       "16. 'touch'\n",
       "17. 'toward'\n",
       "18. 'town'\n",
       "\n",
       "\n"
      ],
      "text/plain": [
       " [1] \"bottom\"     \"doctor\"     \"history\"    \"into\"       \"photograph\"\n",
       " [6] \"stop\"       \"story\"      \"to\"         \"today\"      \"together\"  \n",
       "[11] \"tomorrow\"   \"tonight\"    \"too\"        \"top\"        \"total\"     \n",
       "[16] \"touch\"      \"toward\"     \"town\"      "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "(to_words <- str_subset(words, \"to\"))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<ol class=list-inline>\n",
       "\t<li>'bot2m'</li>\n",
       "\t<li>'doc2r'</li>\n",
       "\t<li>'his2ry'</li>\n",
       "\t<li>'in2'</li>\n",
       "\t<li>'pho2graph'</li>\n",
       "\t<li>'s2p'</li>\n",
       "\t<li>'s2ry'</li>\n",
       "\t<li>'2'</li>\n",
       "\t<li>'2day'</li>\n",
       "\t<li>'2gether'</li>\n",
       "\t<li>'2morrow'</li>\n",
       "\t<li>'2night'</li>\n",
       "\t<li>'2o'</li>\n",
       "\t<li>'2p'</li>\n",
       "\t<li>'2tal'</li>\n",
       "\t<li>'2uch'</li>\n",
       "\t<li>'2ward'</li>\n",
       "\t<li>'2wn'</li>\n",
       "</ol>\n"
      ],
      "text/latex": [
       "\\begin{enumerate*}\n",
       "\\item 'bot2m'\n",
       "\\item 'doc2r'\n",
       "\\item 'his2ry'\n",
       "\\item 'in2'\n",
       "\\item 'pho2graph'\n",
       "\\item 's2p'\n",
       "\\item 's2ry'\n",
       "\\item '2'\n",
       "\\item '2day'\n",
       "\\item '2gether'\n",
       "\\item '2morrow'\n",
       "\\item '2night'\n",
       "\\item '2o'\n",
       "\\item '2p'\n",
       "\\item '2tal'\n",
       "\\item '2uch'\n",
       "\\item '2ward'\n",
       "\\item '2wn'\n",
       "\\end{enumerate*}\n"
      ],
      "text/markdown": [
       "1. 'bot2m'\n",
       "2. 'doc2r'\n",
       "3. 'his2ry'\n",
       "4. 'in2'\n",
       "5. 'pho2graph'\n",
       "6. 's2p'\n",
       "7. 's2ry'\n",
       "8. '2'\n",
       "9. '2day'\n",
       "10. '2gether'\n",
       "11. '2morrow'\n",
       "12. '2night'\n",
       "13. '2o'\n",
       "14. '2p'\n",
       "15. '2tal'\n",
       "16. '2uch'\n",
       "17. '2ward'\n",
       "18. '2wn'\n",
       "\n",
       "\n"
      ],
      "text/plain": [
       " [1] \"bot2m\"     \"doc2r\"     \"his2ry\"    \"in2\"       \"pho2graph\" \"s2p\"      \n",
       " [7] \"s2ry\"      \"2\"         \"2day\"      \"2gether\"   \"2morrow\"   \"2night\"   \n",
       "[13] \"2o\"        \"2p\"        \"2tal\"      \"2uch\"      \"2ward\"     \"2wn\"      "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "str_replace(to_words, \"to\", \"2\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<ol class=list-inline>\n",
       "\t<li>'afford'</li>\n",
       "\t<li>'before'</li>\n",
       "\t<li>'for'</li>\n",
       "\t<li>'force'</li>\n",
       "\t<li>'forget'</li>\n",
       "\t<li>'form'</li>\n",
       "\t<li>'fortune'</li>\n",
       "\t<li>'forward'</li>\n",
       "\t<li>'inform'</li>\n",
       "\t<li>'therefore'</li>\n",
       "</ol>\n"
      ],
      "text/latex": [
       "\\begin{enumerate*}\n",
       "\\item 'afford'\n",
       "\\item 'before'\n",
       "\\item 'for'\n",
       "\\item 'force'\n",
       "\\item 'forget'\n",
       "\\item 'form'\n",
       "\\item 'fortune'\n",
       "\\item 'forward'\n",
       "\\item 'inform'\n",
       "\\item 'therefore'\n",
       "\\end{enumerate*}\n"
      ],
      "text/markdown": [
       "1. 'afford'\n",
       "2. 'before'\n",
       "3. 'for'\n",
       "4. 'force'\n",
       "5. 'forget'\n",
       "6. 'form'\n",
       "7. 'fortune'\n",
       "8. 'forward'\n",
       "9. 'inform'\n",
       "10. 'therefore'\n",
       "\n",
       "\n"
      ],
      "text/plain": [
       " [1] \"afford\"    \"before\"    \"for\"       \"force\"     \"forget\"    \"form\"     \n",
       " [7] \"fortune\"   \"forward\"   \"inform\"    \"therefore\""
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "(for_words <- str_subset(words, \"for\"))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<ol class=list-inline>\n",
       "\t<li>'af4d'</li>\n",
       "\t<li>'be4e'</li>\n",
       "\t<li>'4'</li>\n",
       "\t<li>'4ce'</li>\n",
       "\t<li>'4get'</li>\n",
       "\t<li>'4m'</li>\n",
       "\t<li>'4tune'</li>\n",
       "\t<li>'4ward'</li>\n",
       "\t<li>'in4m'</li>\n",
       "\t<li>'there4e'</li>\n",
       "</ol>\n"
      ],
      "text/latex": [
       "\\begin{enumerate*}\n",
       "\\item 'af4d'\n",
       "\\item 'be4e'\n",
       "\\item '4'\n",
       "\\item '4ce'\n",
       "\\item '4get'\n",
       "\\item '4m'\n",
       "\\item '4tune'\n",
       "\\item '4ward'\n",
       "\\item 'in4m'\n",
       "\\item 'there4e'\n",
       "\\end{enumerate*}\n"
      ],
      "text/markdown": [
       "1. 'af4d'\n",
       "2. 'be4e'\n",
       "3. '4'\n",
       "4. '4ce'\n",
       "5. '4get'\n",
       "6. '4m'\n",
       "7. '4tune'\n",
       "8. '4ward'\n",
       "9. 'in4m'\n",
       "10. 'there4e'\n",
       "\n",
       "\n"
      ],
      "text/plain": [
       " [1] \"af4d\"    \"be4e\"    \"4\"       \"4ce\"     \"4get\"    \"4m\"      \"4tune\"  \n",
       " [8] \"4ward\"   \"in4m\"    \"there4e\""
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "str_replace(for_words, \"for\", \"4\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<ol class=list-inline>\n",
       "\t<li>'Next Tuesday we must vote.'</li>\n",
       "\t<li>'Poached eggs and tea must suffice.'</li>\n",
       "</ol>\n"
      ],
      "text/latex": [
       "\\begin{enumerate*}\n",
       "\\item 'Next Tuesday we must vote.'\n",
       "\\item 'Poached eggs and tea must suffice.'\n",
       "\\end{enumerate*}\n"
      ],
      "text/markdown": [
       "1. 'Next Tuesday we must vote.'\n",
       "2. 'Poached eggs and tea must suffice.'\n",
       "\n",
       "\n"
      ],
      "text/plain": [
       "[1] \"Next Tuesday we must vote.\"         \"Poached eggs and tea must suffice.\""
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "(must_sentences <- str_subset(sentences, \"must\"))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We can also use backreferences in `str_replace`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<ol class=list-inline>\n",
       "\t<li>'Next Tuesday vote, we must'</li>\n",
       "\t<li>'Poached eggs and suffice, tea must'</li>\n",
       "</ol>\n"
      ],
      "text/latex": [
       "\\begin{enumerate*}\n",
       "\\item 'Next Tuesday vote, we must'\n",
       "\\item 'Poached eggs and suffice, tea must'\n",
       "\\end{enumerate*}\n"
      ],
      "text/markdown": [
       "1. 'Next Tuesday vote, we must'\n",
       "2. 'Poached eggs and suffice, tea must'\n",
       "\n",
       "\n"
      ],
      "text/plain": [
       "[1] \"Next Tuesday vote, we must\"         \"Poached eggs and suffice, tea must\""
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "str_replace(must_sentences, \"(.*) ([^ ]*) must (.*)\\\\.\", \"\\\\1 \\\\3, \\\\2 must\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Let's swap the first and last letter in each word in `words`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<ol class=list-inline>\n",
       "\t<li>'a'</li>\n",
       "\t<li>'able'</li>\n",
       "\t<li>'about'</li>\n",
       "\t<li>'absolute'</li>\n",
       "\t<li>'accept'</li>\n",
       "\t<li>'account'</li>\n",
       "\t<li>'achieve'</li>\n",
       "\t<li>'across'</li>\n",
       "\t<li>'act'</li>\n",
       "\t<li>'active'</li>\n",
       "</ol>\n"
      ],
      "text/latex": [
       "\\begin{enumerate*}\n",
       "\\item 'a'\n",
       "\\item 'able'\n",
       "\\item 'about'\n",
       "\\item 'absolute'\n",
       "\\item 'accept'\n",
       "\\item 'account'\n",
       "\\item 'achieve'\n",
       "\\item 'across'\n",
       "\\item 'act'\n",
       "\\item 'active'\n",
       "\\end{enumerate*}\n"
      ],
      "text/markdown": [
       "1. 'a'\n",
       "2. 'able'\n",
       "3. 'about'\n",
       "4. 'absolute'\n",
       "5. 'accept'\n",
       "6. 'account'\n",
       "7. 'achieve'\n",
       "8. 'across'\n",
       "9. 'act'\n",
       "10. 'active'\n",
       "\n",
       "\n"
      ],
      "text/plain": [
       " [1] \"a\"        \"able\"     \"about\"    \"absolute\" \"accept\"   \"account\" \n",
       " [7] \"achieve\"  \"across\"   \"act\"      \"active\"  "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "data": {
      "text/html": [
       "<ol class=list-inline>\n",
       "\t<li>'a'</li>\n",
       "\t<li>'ebla'</li>\n",
       "\t<li>'tboua'</li>\n",
       "\t<li>'ebsoluta'</li>\n",
       "\t<li>'tccepa'</li>\n",
       "\t<li>'tccouna'</li>\n",
       "\t<li>'echieva'</li>\n",
       "\t<li>'scrosa'</li>\n",
       "\t<li>'tca'</li>\n",
       "\t<li>'ectiva'</li>\n",
       "</ol>\n"
      ],
      "text/latex": [
       "\\begin{enumerate*}\n",
       "\\item 'a'\n",
       "\\item 'ebla'\n",
       "\\item 'tboua'\n",
       "\\item 'ebsoluta'\n",
       "\\item 'tccepa'\n",
       "\\item 'tccouna'\n",
       "\\item 'echieva'\n",
       "\\item 'scrosa'\n",
       "\\item 'tca'\n",
       "\\item 'ectiva'\n",
       "\\end{enumerate*}\n"
      ],
      "text/markdown": [
       "1. 'a'\n",
       "2. 'ebla'\n",
       "3. 'tboua'\n",
       "4. 'ebsoluta'\n",
       "5. 'tccepa'\n",
       "6. 'tccouna'\n",
       "7. 'echieva'\n",
       "8. 'scrosa'\n",
       "9. 'tca'\n",
       "10. 'ectiva'\n",
       "\n",
       "\n"
      ],
      "text/plain": [
       " [1] \"a\"        \"ebla\"     \"tboua\"    \"ebsoluta\" \"tccepa\"   \"tccouna\" \n",
       " [7] \"echieva\"  \"scrosa\"   \"tca\"      \"ectiva\"  "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "words %>% head(10)\n",
    "str_replace(words, \"^(.)(.*)(.)$\", \"\\\\3\\\\2\\\\1\") %>% head(10)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Splitting"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<ol>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>''</li>\n",
       "\t<li>''</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>''</li>\n",
       "\t<li>'bl'</li>\n",
       "\t<li>''</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>''</li>\n",
       "\t<li>'b'</li>\n",
       "\t<li>''</li>\n",
       "\t<li>'t'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>''</li>\n",
       "\t<li>'bs'</li>\n",
       "\t<li>'l'</li>\n",
       "\t<li>'t'</li>\n",
       "\t<li>''</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>''</li>\n",
       "\t<li>'cc'</li>\n",
       "\t<li>'pt'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>''</li>\n",
       "\t<li>'cc'</li>\n",
       "\t<li>''</li>\n",
       "\t<li>'nt'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>''</li>\n",
       "\t<li>'ch'</li>\n",
       "\t<li>''</li>\n",
       "\t<li>'v'</li>\n",
       "\t<li>''</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>''</li>\n",
       "\t<li>'cr'</li>\n",
       "\t<li>'ss'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>''</li>\n",
       "\t<li>'ct'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>''</li>\n",
       "\t<li>'ct'</li>\n",
       "\t<li>'v'</li>\n",
       "\t<li>''</li>\n",
       "</ol>\n",
       "</li>\n",
       "</ol>\n"
      ],
      "text/latex": [
       "\\begin{enumerate}\n",
       "\\item \\begin{enumerate*}\n",
       "\\item ''\n",
       "\\item ''\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item ''\n",
       "\\item 'bl'\n",
       "\\item ''\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item ''\n",
       "\\item 'b'\n",
       "\\item ''\n",
       "\\item 't'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item ''\n",
       "\\item 'bs'\n",
       "\\item 'l'\n",
       "\\item 't'\n",
       "\\item ''\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item ''\n",
       "\\item 'cc'\n",
       "\\item 'pt'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item ''\n",
       "\\item 'cc'\n",
       "\\item ''\n",
       "\\item 'nt'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item ''\n",
       "\\item 'ch'\n",
       "\\item ''\n",
       "\\item 'v'\n",
       "\\item ''\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item ''\n",
       "\\item 'cr'\n",
       "\\item 'ss'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item ''\n",
       "\\item 'ct'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item ''\n",
       "\\item 'ct'\n",
       "\\item 'v'\n",
       "\\item ''\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\end{enumerate}\n"
      ],
      "text/markdown": [
       "1. 1. ''\n",
       "2. ''\n",
       "\n",
       "\n",
       "\n",
       "2. 1. ''\n",
       "2. 'bl'\n",
       "3. ''\n",
       "\n",
       "\n",
       "\n",
       "3. 1. ''\n",
       "2. 'b'\n",
       "3. ''\n",
       "4. 't'\n",
       "\n",
       "\n",
       "\n",
       "4. 1. ''\n",
       "2. 'bs'\n",
       "3. 'l'\n",
       "4. 't'\n",
       "5. ''\n",
       "\n",
       "\n",
       "\n",
       "5. 1. ''\n",
       "2. 'cc'\n",
       "3. 'pt'\n",
       "\n",
       "\n",
       "\n",
       "6. 1. ''\n",
       "2. 'cc'\n",
       "3. ''\n",
       "4. 'nt'\n",
       "\n",
       "\n",
       "\n",
       "7. 1. ''\n",
       "2. 'ch'\n",
       "3. ''\n",
       "4. 'v'\n",
       "5. ''\n",
       "\n",
       "\n",
       "\n",
       "8. 1. ''\n",
       "2. 'cr'\n",
       "3. 'ss'\n",
       "\n",
       "\n",
       "\n",
       "9. 1. ''\n",
       "2. 'ct'\n",
       "\n",
       "\n",
       "\n",
       "10. 1. ''\n",
       "2. 'ct'\n",
       "3. 'v'\n",
       "4. ''\n",
       "\n",
       "\n",
       "\n",
       "\n",
       "\n"
      ],
      "text/plain": [
       "[[1]]\n",
       "[1] \"\" \"\"\n",
       "\n",
       "[[2]]\n",
       "[1] \"\"   \"bl\" \"\"  \n",
       "\n",
       "[[3]]\n",
       "[1] \"\"  \"b\" \"\"  \"t\"\n",
       "\n",
       "[[4]]\n",
       "[1] \"\"   \"bs\" \"l\"  \"t\"  \"\"  \n",
       "\n",
       "[[5]]\n",
       "[1] \"\"   \"cc\" \"pt\"\n",
       "\n",
       "[[6]]\n",
       "[1] \"\"   \"cc\" \"\"   \"nt\"\n",
       "\n",
       "[[7]]\n",
       "[1] \"\"   \"ch\" \"\"   \"v\"  \"\"  \n",
       "\n",
       "[[8]]\n",
       "[1] \"\"   \"cr\" \"ss\"\n",
       "\n",
       "[[9]]\n",
       "[1] \"\"   \"ct\"\n",
       "\n",
       "[[10]]\n",
       "[1] \"\"   \"ct\" \"v\"  \"\"  \n"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "words %>%\n",
    "    head(10) %>%\n",
    "    str_split(\"[aeiou]\") # split up words by vowels"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<table>\n",
       "<caption>A matrix: 10 × 5 of type chr</caption>\n",
       "<tbody>\n",
       "\t<tr><td></td><td>  </td><td>  </td><td>  </td><td></td></tr>\n",
       "\t<tr><td></td><td>bl</td><td>  </td><td>  </td><td></td></tr>\n",
       "\t<tr><td></td><td>b </td><td>  </td><td>t </td><td></td></tr>\n",
       "\t<tr><td></td><td>bs</td><td>l </td><td>t </td><td></td></tr>\n",
       "\t<tr><td></td><td>cc</td><td>pt</td><td>  </td><td></td></tr>\n",
       "\t<tr><td></td><td>cc</td><td>  </td><td>nt</td><td></td></tr>\n",
       "\t<tr><td></td><td>ch</td><td>  </td><td>v </td><td></td></tr>\n",
       "\t<tr><td></td><td>cr</td><td>ss</td><td>  </td><td></td></tr>\n",
       "\t<tr><td></td><td>ct</td><td>  </td><td>  </td><td></td></tr>\n",
       "\t<tr><td></td><td>ct</td><td>v </td><td>  </td><td></td></tr>\n",
       "</tbody>\n",
       "</table>\n"
      ],
      "text/latex": [
       "A matrix: 10 × 5 of type chr\n",
       "\\begin{tabular}{lllll}\n",
       "\t  &    &    &    & \\\\\n",
       "\t  & bl &    &    & \\\\\n",
       "\t  & b  &    & t  & \\\\\n",
       "\t  & bs & l  & t  & \\\\\n",
       "\t  & cc & pt &    & \\\\\n",
       "\t  & cc &    & nt & \\\\\n",
       "\t  & ch &    & v  & \\\\\n",
       "\t  & cr & ss &    & \\\\\n",
       "\t  & ct &    &    & \\\\\n",
       "\t  & ct & v  &    & \\\\\n",
       "\\end{tabular}\n"
      ],
      "text/markdown": [
       "\n",
       "A matrix: 10 × 5 of type chr\n",
       "\n",
       "| <!----> | <!----> | <!----> | <!----> | <!----> |\n",
       "| <!----> | bl | <!----> | <!----> | <!----> |\n",
       "| <!----> | b  | <!----> | t  | <!----> |\n",
       "| <!----> | bs | l  | t  | <!----> |\n",
       "| <!----> | cc | pt | <!----> | <!----> |\n",
       "| <!----> | cc | <!----> | nt | <!----> |\n",
       "| <!----> | ch | <!----> | v  | <!----> |\n",
       "| <!----> | cr | ss | <!----> | <!----> |\n",
       "| <!----> | ct | <!----> | <!----> | <!----> |\n",
       "| <!----> | ct | v  | <!----> | <!----> |\n",
       "\n"
      ],
      "text/plain": [
       "      [,1] [,2] [,3] [,4] [,5]\n",
       " [1,]                         \n",
       " [2,]      bl                 \n",
       " [3,]      b         t        \n",
       " [4,]      bs   l    t        \n",
       " [5,]      cc   pt            \n",
       " [6,]      cc        nt       \n",
       " [7,]      ch        v        \n",
       " [8,]      cr   ss            \n",
       " [9,]      ct                 \n",
       "[10,]      ct   v             "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "words %>%\n",
    "    head(10) %>%\n",
    "    str_split(\"[aeiou]\", simplify = TRUE) # to get a matrix"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<ol>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'The'</li>\n",
       "\t<li>'birch'</li>\n",
       "\t<li>'canoe'</li>\n",
       "\t<li>'slid'</li>\n",
       "\t<li>'on'</li>\n",
       "\t<li>'the'</li>\n",
       "\t<li>'smooth'</li>\n",
       "\t<li>'planks.'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'Glue'</li>\n",
       "\t<li>'the'</li>\n",
       "\t<li>'sheet'</li>\n",
       "\t<li>'to'</li>\n",
       "\t<li>'the'</li>\n",
       "\t<li>'dark'</li>\n",
       "\t<li>'blue'</li>\n",
       "\t<li>'background.'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'It\\'s'</li>\n",
       "\t<li>'easy'</li>\n",
       "\t<li>'to'</li>\n",
       "\t<li>'tell'</li>\n",
       "\t<li>'the'</li>\n",
       "\t<li>'depth'</li>\n",
       "\t<li>'of'</li>\n",
       "\t<li>'a'</li>\n",
       "\t<li>'well.'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'These'</li>\n",
       "\t<li>'days'</li>\n",
       "\t<li>'a'</li>\n",
       "\t<li>'chicken'</li>\n",
       "\t<li>'leg'</li>\n",
       "\t<li>'is'</li>\n",
       "\t<li>'a'</li>\n",
       "\t<li>'rare'</li>\n",
       "\t<li>'dish.'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'Rice'</li>\n",
       "\t<li>'is'</li>\n",
       "\t<li>'often'</li>\n",
       "\t<li>'served'</li>\n",
       "\t<li>'in'</li>\n",
       "\t<li>'round'</li>\n",
       "\t<li>'bowls.'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'The'</li>\n",
       "\t<li>'juice'</li>\n",
       "\t<li>'of'</li>\n",
       "\t<li>'lemons'</li>\n",
       "\t<li>'makes'</li>\n",
       "\t<li>'fine'</li>\n",
       "\t<li>'punch.'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'The'</li>\n",
       "\t<li>'box'</li>\n",
       "\t<li>'was'</li>\n",
       "\t<li>'thrown'</li>\n",
       "\t<li>'beside'</li>\n",
       "\t<li>'the'</li>\n",
       "\t<li>'parked'</li>\n",
       "\t<li>'truck.'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'The'</li>\n",
       "\t<li>'hogs'</li>\n",
       "\t<li>'were'</li>\n",
       "\t<li>'fed'</li>\n",
       "\t<li>'chopped'</li>\n",
       "\t<li>'corn'</li>\n",
       "\t<li>'and'</li>\n",
       "\t<li>'garbage.'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'Four'</li>\n",
       "\t<li>'hours'</li>\n",
       "\t<li>'of'</li>\n",
       "\t<li>'steady'</li>\n",
       "\t<li>'work'</li>\n",
       "\t<li>'faced'</li>\n",
       "\t<li>'us.'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'Large'</li>\n",
       "\t<li>'size'</li>\n",
       "\t<li>'in'</li>\n",
       "\t<li>'stockings'</li>\n",
       "\t<li>'is'</li>\n",
       "\t<li>'hard'</li>\n",
       "\t<li>'to'</li>\n",
       "\t<li>'sell.'</li>\n",
       "</ol>\n",
       "</li>\n",
       "</ol>\n"
      ],
      "text/latex": [
       "\\begin{enumerate}\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'The'\n",
       "\\item 'birch'\n",
       "\\item 'canoe'\n",
       "\\item 'slid'\n",
       "\\item 'on'\n",
       "\\item 'the'\n",
       "\\item 'smooth'\n",
       "\\item 'planks.'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'Glue'\n",
       "\\item 'the'\n",
       "\\item 'sheet'\n",
       "\\item 'to'\n",
       "\\item 'the'\n",
       "\\item 'dark'\n",
       "\\item 'blue'\n",
       "\\item 'background.'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'It\\textbackslash{}'s'\n",
       "\\item 'easy'\n",
       "\\item 'to'\n",
       "\\item 'tell'\n",
       "\\item 'the'\n",
       "\\item 'depth'\n",
       "\\item 'of'\n",
       "\\item 'a'\n",
       "\\item 'well.'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'These'\n",
       "\\item 'days'\n",
       "\\item 'a'\n",
       "\\item 'chicken'\n",
       "\\item 'leg'\n",
       "\\item 'is'\n",
       "\\item 'a'\n",
       "\\item 'rare'\n",
       "\\item 'dish.'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'Rice'\n",
       "\\item 'is'\n",
       "\\item 'often'\n",
       "\\item 'served'\n",
       "\\item 'in'\n",
       "\\item 'round'\n",
       "\\item 'bowls.'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'The'\n",
       "\\item 'juice'\n",
       "\\item 'of'\n",
       "\\item 'lemons'\n",
       "\\item 'makes'\n",
       "\\item 'fine'\n",
       "\\item 'punch.'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'The'\n",
       "\\item 'box'\n",
       "\\item 'was'\n",
       "\\item 'thrown'\n",
       "\\item 'beside'\n",
       "\\item 'the'\n",
       "\\item 'parked'\n",
       "\\item 'truck.'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'The'\n",
       "\\item 'hogs'\n",
       "\\item 'were'\n",
       "\\item 'fed'\n",
       "\\item 'chopped'\n",
       "\\item 'corn'\n",
       "\\item 'and'\n",
       "\\item 'garbage.'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'Four'\n",
       "\\item 'hours'\n",
       "\\item 'of'\n",
       "\\item 'steady'\n",
       "\\item 'work'\n",
       "\\item 'faced'\n",
       "\\item 'us.'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'Large'\n",
       "\\item 'size'\n",
       "\\item 'in'\n",
       "\\item 'stockings'\n",
       "\\item 'is'\n",
       "\\item 'hard'\n",
       "\\item 'to'\n",
       "\\item 'sell.'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\end{enumerate}\n"
      ],
      "text/markdown": [
       "1. 1. 'The'\n",
       "2. 'birch'\n",
       "3. 'canoe'\n",
       "4. 'slid'\n",
       "5. 'on'\n",
       "6. 'the'\n",
       "7. 'smooth'\n",
       "8. 'planks.'\n",
       "\n",
       "\n",
       "\n",
       "2. 1. 'Glue'\n",
       "2. 'the'\n",
       "3. 'sheet'\n",
       "4. 'to'\n",
       "5. 'the'\n",
       "6. 'dark'\n",
       "7. 'blue'\n",
       "8. 'background.'\n",
       "\n",
       "\n",
       "\n",
       "3. 1. 'It\\'s'\n",
       "2. 'easy'\n",
       "3. 'to'\n",
       "4. 'tell'\n",
       "5. 'the'\n",
       "6. 'depth'\n",
       "7. 'of'\n",
       "8. 'a'\n",
       "9. 'well.'\n",
       "\n",
       "\n",
       "\n",
       "4. 1. 'These'\n",
       "2. 'days'\n",
       "3. 'a'\n",
       "4. 'chicken'\n",
       "5. 'leg'\n",
       "6. 'is'\n",
       "7. 'a'\n",
       "8. 'rare'\n",
       "9. 'dish.'\n",
       "\n",
       "\n",
       "\n",
       "5. 1. 'Rice'\n",
       "2. 'is'\n",
       "3. 'often'\n",
       "4. 'served'\n",
       "5. 'in'\n",
       "6. 'round'\n",
       "7. 'bowls.'\n",
       "\n",
       "\n",
       "\n",
       "6. 1. 'The'\n",
       "2. 'juice'\n",
       "3. 'of'\n",
       "4. 'lemons'\n",
       "5. 'makes'\n",
       "6. 'fine'\n",
       "7. 'punch.'\n",
       "\n",
       "\n",
       "\n",
       "7. 1. 'The'\n",
       "2. 'box'\n",
       "3. 'was'\n",
       "4. 'thrown'\n",
       "5. 'beside'\n",
       "6. 'the'\n",
       "7. 'parked'\n",
       "8. 'truck.'\n",
       "\n",
       "\n",
       "\n",
       "8. 1. 'The'\n",
       "2. 'hogs'\n",
       "3. 'were'\n",
       "4. 'fed'\n",
       "5. 'chopped'\n",
       "6. 'corn'\n",
       "7. 'and'\n",
       "8. 'garbage.'\n",
       "\n",
       "\n",
       "\n",
       "9. 1. 'Four'\n",
       "2. 'hours'\n",
       "3. 'of'\n",
       "4. 'steady'\n",
       "5. 'work'\n",
       "6. 'faced'\n",
       "7. 'us.'\n",
       "\n",
       "\n",
       "\n",
       "10. 1. 'Large'\n",
       "2. 'size'\n",
       "3. 'in'\n",
       "4. 'stockings'\n",
       "5. 'is'\n",
       "6. 'hard'\n",
       "7. 'to'\n",
       "8. 'sell.'\n",
       "\n",
       "\n",
       "\n",
       "\n",
       "\n"
      ],
      "text/plain": [
       "[[1]]\n",
       "[1] \"The\"     \"birch\"   \"canoe\"   \"slid\"    \"on\"      \"the\"     \"smooth\" \n",
       "[8] \"planks.\"\n",
       "\n",
       "[[2]]\n",
       "[1] \"Glue\"        \"the\"         \"sheet\"       \"to\"          \"the\"        \n",
       "[6] \"dark\"        \"blue\"        \"background.\"\n",
       "\n",
       "[[3]]\n",
       "[1] \"It's\"  \"easy\"  \"to\"    \"tell\"  \"the\"   \"depth\" \"of\"    \"a\"     \"well.\"\n",
       "\n",
       "[[4]]\n",
       "[1] \"These\"   \"days\"    \"a\"       \"chicken\" \"leg\"     \"is\"      \"a\"      \n",
       "[8] \"rare\"    \"dish.\"  \n",
       "\n",
       "[[5]]\n",
       "[1] \"Rice\"   \"is\"     \"often\"  \"served\" \"in\"     \"round\"  \"bowls.\"\n",
       "\n",
       "[[6]]\n",
       "[1] \"The\"    \"juice\"  \"of\"     \"lemons\" \"makes\"  \"fine\"   \"punch.\"\n",
       "\n",
       "[[7]]\n",
       "[1] \"The\"    \"box\"    \"was\"    \"thrown\" \"beside\" \"the\"    \"parked\" \"truck.\"\n",
       "\n",
       "[[8]]\n",
       "[1] \"The\"      \"hogs\"     \"were\"     \"fed\"      \"chopped\"  \"corn\"     \"and\"     \n",
       "[8] \"garbage.\"\n",
       "\n",
       "[[9]]\n",
       "[1] \"Four\"   \"hours\"  \"of\"     \"steady\" \"work\"   \"faced\"  \"us.\"   \n",
       "\n",
       "[[10]]\n",
       "[1] \"Large\"     \"size\"      \"in\"        \"stockings\" \"is\"        \"hard\"     \n",
       "[7] \"to\"        \"sell.\"    \n"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "sentences %>%\n",
    "    head(10) %>%\n",
    "    str_split(\"\\\\s\") # split sentences on whitespace"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<ol>\n",
       "\t<li>'a'</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'a'</li>\n",
       "\t<li>'b'</li>\n",
       "\t<li>'l'</li>\n",
       "\t<li>'e'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'a'</li>\n",
       "\t<li>'b'</li>\n",
       "\t<li>'o'</li>\n",
       "\t<li>'u'</li>\n",
       "\t<li>'t'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'a'</li>\n",
       "\t<li>'b'</li>\n",
       "\t<li>'s'</li>\n",
       "\t<li>'o'</li>\n",
       "\t<li>'l'</li>\n",
       "\t<li>'u'</li>\n",
       "\t<li>'t'</li>\n",
       "\t<li>'e'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'a'</li>\n",
       "\t<li>'c'</li>\n",
       "\t<li>'c'</li>\n",
       "\t<li>'e'</li>\n",
       "\t<li>'p'</li>\n",
       "\t<li>'t'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'a'</li>\n",
       "\t<li>'c'</li>\n",
       "\t<li>'c'</li>\n",
       "\t<li>'o'</li>\n",
       "\t<li>'u'</li>\n",
       "\t<li>'n'</li>\n",
       "\t<li>'t'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'a'</li>\n",
       "\t<li>'c'</li>\n",
       "\t<li>'h'</li>\n",
       "\t<li>'i'</li>\n",
       "\t<li>'e'</li>\n",
       "\t<li>'v'</li>\n",
       "\t<li>'e'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'a'</li>\n",
       "\t<li>'c'</li>\n",
       "\t<li>'r'</li>\n",
       "\t<li>'o'</li>\n",
       "\t<li>'s'</li>\n",
       "\t<li>'s'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'a'</li>\n",
       "\t<li>'c'</li>\n",
       "\t<li>'t'</li>\n",
       "</ol>\n",
       "</li>\n",
       "\t<li><ol class=list-inline>\n",
       "\t<li>'a'</li>\n",
       "\t<li>'c'</li>\n",
       "\t<li>'t'</li>\n",
       "\t<li>'i'</li>\n",
       "\t<li>'v'</li>\n",
       "\t<li>'e'</li>\n",
       "</ol>\n",
       "</li>\n",
       "</ol>\n"
      ],
      "text/latex": [
       "\\begin{enumerate}\n",
       "\\item 'a'\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'a'\n",
       "\\item 'b'\n",
       "\\item 'l'\n",
       "\\item 'e'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'a'\n",
       "\\item 'b'\n",
       "\\item 'o'\n",
       "\\item 'u'\n",
       "\\item 't'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'a'\n",
       "\\item 'b'\n",
       "\\item 's'\n",
       "\\item 'o'\n",
       "\\item 'l'\n",
       "\\item 'u'\n",
       "\\item 't'\n",
       "\\item 'e'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'a'\n",
       "\\item 'c'\n",
       "\\item 'c'\n",
       "\\item 'e'\n",
       "\\item 'p'\n",
       "\\item 't'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'a'\n",
       "\\item 'c'\n",
       "\\item 'c'\n",
       "\\item 'o'\n",
       "\\item 'u'\n",
       "\\item 'n'\n",
       "\\item 't'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'a'\n",
       "\\item 'c'\n",
       "\\item 'h'\n",
       "\\item 'i'\n",
       "\\item 'e'\n",
       "\\item 'v'\n",
       "\\item 'e'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'a'\n",
       "\\item 'c'\n",
       "\\item 'r'\n",
       "\\item 'o'\n",
       "\\item 's'\n",
       "\\item 's'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'a'\n",
       "\\item 'c'\n",
       "\\item 't'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\item \\begin{enumerate*}\n",
       "\\item 'a'\n",
       "\\item 'c'\n",
       "\\item 't'\n",
       "\\item 'i'\n",
       "\\item 'v'\n",
       "\\item 'e'\n",
       "\\end{enumerate*}\n",
       "\n",
       "\\end{enumerate}\n"
      ],
      "text/markdown": [
       "1. 'a'\n",
       "2. 1. 'a'\n",
       "2. 'b'\n",
       "3. 'l'\n",
       "4. 'e'\n",
       "\n",
       "\n",
       "\n",
       "3. 1. 'a'\n",
       "2. 'b'\n",
       "3. 'o'\n",
       "4. 'u'\n",
       "5. 't'\n",
       "\n",
       "\n",
       "\n",
       "4. 1. 'a'\n",
       "2. 'b'\n",
       "3. 's'\n",
       "4. 'o'\n",
       "5. 'l'\n",
       "6. 'u'\n",
       "7. 't'\n",
       "8. 'e'\n",
       "\n",
       "\n",
       "\n",
       "5. 1. 'a'\n",
       "2. 'c'\n",
       "3. 'c'\n",
       "4. 'e'\n",
       "5. 'p'\n",
       "6. 't'\n",
       "\n",
       "\n",
       "\n",
       "6. 1. 'a'\n",
       "2. 'c'\n",
       "3. 'c'\n",
       "4. 'o'\n",
       "5. 'u'\n",
       "6. 'n'\n",
       "7. 't'\n",
       "\n",
       "\n",
       "\n",
       "7. 1. 'a'\n",
       "2. 'c'\n",
       "3. 'h'\n",
       "4. 'i'\n",
       "5. 'e'\n",
       "6. 'v'\n",
       "7. 'e'\n",
       "\n",
       "\n",
       "\n",
       "8. 1. 'a'\n",
       "2. 'c'\n",
       "3. 'r'\n",
       "4. 'o'\n",
       "5. 's'\n",
       "6. 's'\n",
       "\n",
       "\n",
       "\n",
       "9. 1. 'a'\n",
       "2. 'c'\n",
       "3. 't'\n",
       "\n",
       "\n",
       "\n",
       "10. 1. 'a'\n",
       "2. 'c'\n",
       "3. 't'\n",
       "4. 'i'\n",
       "5. 'v'\n",
       "6. 'e'\n",
       "\n",
       "\n",
       "\n",
       "\n",
       "\n"
      ],
      "text/plain": [
       "[[1]]\n",
       "[1] \"a\"\n",
       "\n",
       "[[2]]\n",
       "[1] \"a\" \"b\" \"l\" \"e\"\n",
       "\n",
       "[[3]]\n",
       "[1] \"a\" \"b\" \"o\" \"u\" \"t\"\n",
       "\n",
       "[[4]]\n",
       "[1] \"a\" \"b\" \"s\" \"o\" \"l\" \"u\" \"t\" \"e\"\n",
       "\n",
       "[[5]]\n",
       "[1] \"a\" \"c\" \"c\" \"e\" \"p\" \"t\"\n",
       "\n",
       "[[6]]\n",
       "[1] \"a\" \"c\" \"c\" \"o\" \"u\" \"n\" \"t\"\n",
       "\n",
       "[[7]]\n",
       "[1] \"a\" \"c\" \"h\" \"i\" \"e\" \"v\" \"e\"\n",
       "\n",
       "[[8]]\n",
       "[1] \"a\" \"c\" \"r\" \"o\" \"s\" \"s\"\n",
       "\n",
       "[[9]]\n",
       "[1] \"a\" \"c\" \"t\"\n",
       "\n",
       "[[10]]\n",
       "[1] \"a\" \"c\" \"t\" \"i\" \"v\" \"e\"\n"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "words %>%\n",
    "    head(10) %>%\n",
    "    str_split(\"\") # splitting by empty string splits into individual characters"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Find matches"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<table>\n",
       "<caption>A matrix: 44 × 2 of type int</caption>\n",
       "<thead>\n",
       "\t<tr><th scope=col>start</th><th scope=col>end</th></tr>\n",
       "</thead>\n",
       "<tbody>\n",
       "\t<tr><td>3</td><td>4</td></tr>\n",
       "\t<tr><td>4</td><td>5</td></tr>\n",
       "\t<tr><td>3</td><td>4</td></tr>\n",
       "\t<tr><td>4</td><td>5</td></tr>\n",
       "\t<tr><td>3</td><td>4</td></tr>\n",
       "\t<tr><td>3</td><td>4</td></tr>\n",
       "\t<tr><td>4</td><td>5</td></tr>\n",
       "\t<tr><td>4</td><td>5</td></tr>\n",
       "\t<tr><td>3</td><td>4</td></tr>\n",
       "\t<tr><td>3</td><td>4</td></tr>\n",
       "\t<tr><td>4</td><td>5</td></tr>\n",
       "\t<tr><td>5</td><td>6</td></tr>\n",
       "\t<tr><td>4</td><td>5</td></tr>\n",
       "\t<tr><td>3</td><td>4</td></tr>\n",
       "\t<tr><td>4</td><td>5</td></tr>\n",
       "\t<tr><td>2</td><td>3</td></tr>\n",
       "\t<tr><td>2</td><td>3</td></tr>\n",
       "\t<tr><td>3</td><td>4</td></tr>\n",
       "\t<tr><td>4</td><td>5</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>1</td><td>2</td></tr>\n",
       "\t<tr><td>5</td><td>6</td></tr>\n",
       "\t<tr><td>4</td><td>5</td></tr>\n",
       "\t<tr><td>3</td><td>4</td></tr>\n",
       "\t<tr><td>3</td><td>4</td></tr>\n",
       "\t<tr><td>3</td><td>4</td></tr>\n",
       "\t<tr><td>4</td><td>5</td></tr>\n",
       "</tbody>\n",
       "</table>\n"
      ],
      "text/latex": [
       "A matrix: 44 × 2 of type int\n",
       "\\begin{tabular}{ll}\n",
       " start & end\\\\\n",
       "\\hline\n",
       "\t 3 & 4\\\\\n",
       "\t 4 & 5\\\\\n",
       "\t 3 & 4\\\\\n",
       "\t 4 & 5\\\\\n",
       "\t 3 & 4\\\\\n",
       "\t 3 & 4\\\\\n",
       "\t 4 & 5\\\\\n",
       "\t 4 & 5\\\\\n",
       "\t 3 & 4\\\\\n",
       "\t 3 & 4\\\\\n",
       "\t 4 & 5\\\\\n",
       "\t 5 & 6\\\\\n",
       "\t 4 & 5\\\\\n",
       "\t 3 & 4\\\\\n",
       "\t 4 & 5\\\\\n",
       "\t 2 & 3\\\\\n",
       "\t 2 & 3\\\\\n",
       "\t 3 & 4\\\\\n",
       "\t 4 & 5\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 1 & 2\\\\\n",
       "\t 5 & 6\\\\\n",
       "\t 4 & 5\\\\\n",
       "\t 3 & 4\\\\\n",
       "\t 3 & 4\\\\\n",
       "\t 3 & 4\\\\\n",
       "\t 4 & 5\\\\\n",
       "\\end{tabular}\n"
      ],
      "text/markdown": [
       "\n",
       "A matrix: 44 × 2 of type int\n",
       "\n",
       "| start | end |\n",
       "|---|---|\n",
       "| 3 | 4 |\n",
       "| 4 | 5 |\n",
       "| 3 | 4 |\n",
       "| 4 | 5 |\n",
       "| 3 | 4 |\n",
       "| 3 | 4 |\n",
       "| 4 | 5 |\n",
       "| 4 | 5 |\n",
       "| 3 | 4 |\n",
       "| 3 | 4 |\n",
       "| 4 | 5 |\n",
       "| 5 | 6 |\n",
       "| 4 | 5 |\n",
       "| 3 | 4 |\n",
       "| 4 | 5 |\n",
       "| 2 | 3 |\n",
       "| 2 | 3 |\n",
       "| 3 | 4 |\n",
       "| 4 | 5 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 1 | 2 |\n",
       "| 5 | 6 |\n",
       "| 4 | 5 |\n",
       "| 3 | 4 |\n",
       "| 3 | 4 |\n",
       "| 3 | 4 |\n",
       "| 4 | 5 |\n",
       "\n"
      ],
      "text/plain": [
       "      start end\n",
       " [1,] 3     4  \n",
       " [2,] 4     5  \n",
       " [3,] 3     4  \n",
       " [4,] 4     5  \n",
       " [5,] 3     4  \n",
       " [6,] 3     4  \n",
       " [7,] 4     5  \n",
       " [8,] 4     5  \n",
       " [9,] 3     4  \n",
       "[10,] 3     4  \n",
       "[11,] 4     5  \n",
       "[12,] 5     6  \n",
       "[13,] 4     5  \n",
       "[14,] 3     4  \n",
       "[15,] 4     5  \n",
       "[16,] 2     3  \n",
       "[17,] 2     3  \n",
       "[18,] 3     4  \n",
       "[19,] 4     5  \n",
       "[20,] 1     2  \n",
       "[21,] 1     2  \n",
       "[22,] 1     2  \n",
       "[23,] 1     2  \n",
       "[24,] 1     2  \n",
       "[25,] 1     2  \n",
       "[26,] 1     2  \n",
       "[27,] 1     2  \n",
       "[28,] 1     2  \n",
       "[29,] 1     2  \n",
       "[30,] 1     2  \n",
       "[31,] 1     2  \n",
       "[32,] 1     2  \n",
       "[33,] 1     2  \n",
       "[34,] 1     2  \n",
       "[35,] 1     2  \n",
       "[36,] 1     2  \n",
       "[37,] 1     2  \n",
       "[38,] 1     2  \n",
       "[39,] 5     6  \n",
       "[40,] 4     5  \n",
       "[41,] 3     4  \n",
       "[42,] 3     4  \n",
       "[43,] 3     4  \n",
       "[44,] 4     5  "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "regex <- \"th\"\n",
    "words %>%\n",
    "    str_subset(regex) %>%\n",
    "    str_locate(regex)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [],
   "source": [
    "library(stringi) # for the stri_dup function"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1] \"You owe me $XXX\"\n",
      "[1] \"I gave you $XX\"\n",
      "[1] \"We owe $XXXX to the bank\"\n"
     ]
    }
   ],
   "source": [
    "x <- c(\"You owe me $560\", \"I gave you $40\", \"We owe $3100 to the bank\")\n",
    "for (str in x) {\n",
    "    location <- str_locate(str, \"\\\\$\\\\d+\")\n",
    "    start <- location[1]\n",
    "    end <- location[2]\n",
    "    str_sub(str, start, end) <- str_c(\"$\", stri_dup(\"X\", end-start))\n",
    "    print(str)\n",
    "}"
   ]
  }
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