{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Using regular expressions to search texts for patterns\n",
    "\n",
    "### Dowload sample corpora"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "%%time\n",
    "!wget -c https://object.pouta.csc.fi/OPUS-OpenSubtitles/v2018/tmx/en-zh_tw.tmx.gz"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "%%time\n",
    "!wget -c http://nlp.csie.org/~rubentsui/files/TranslationTech1082/Regex/nytimes.txt.gz"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "%%!\n",
    "gunzip en-zh_tw.tmx.gz\n",
    "gunzip nytimes.txt.gz"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Search OpenSubtitles 2018"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "%%time\n",
    "phrase = '發酒瘋'; corpus = 'en-zh_tw.tmx'\n",
    "!fgrep -B1 \"$phrase\" $corpus --color=always | sed '/--/d' "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Search sample New York Times corpus"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "%%time\n",
    "regex = 'performance[- ]enhanc\\w+ \\w+'\n",
    "corpus = 'nytimes.txt'\n",
    "print(\"Phrases matched and their frequencies:\")\n",
    "!egrep -i -o \"$regex\" $corpus | sort | uniq -c | sort -nr\n",
    "print(\"\\nConcordancer output:\")\n",
    "!egrep -i -A1 \"$regex\" $corpus  --color=always "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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