Week_2/wek/Regex_python.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import re"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Search command\n",
    "regex = r\"([a-zA-Z]+) (\\d+)\"\n",
    "input_str = \"June 24\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "([a-zA-Z]+) (\\d+)\n"
     ]
    }
   ],
   "source": [
    "print(regex)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Matching a String"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## re.search(regex search, string)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<re.Match object; span=(0, 7), match='June 24'>"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "match = re.search(regex, input_str)\n",
    "match"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Match at index 0, 7\n"
     ]
    }
   ],
   "source": [
    "print(\"Match at index %s, %s\" % (match.start(), match.end()))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Full match: June 24\n",
      "Month: June\n",
      "Day: 24\n"
     ]
    }
   ],
   "source": [
    "print(\"Full match: %s\" % (match.group(0)))\n",
    "print(\"Month: %s\" % (match.group(1)))\n",
    "print(\"Day: %s\" % (match.group(2)))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Capturing Strings"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## re.findall(regex search, input_str, flags=0)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## re.finditer(regex search, input_str, flags=0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['June 24', 'August 9', 'Dec 12']"
      ]
     },
     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "regex = r\"[a-zA-Z]+ \\d+\"\n",
    "input_str = \"June 24, August 9, Dec 12\"\n",
    "matches = re.findall(regex, input_str)\n",
    "matches"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "June 24\n",
      "August 9\n",
      "Dec 12\n"
     ]
    }
   ],
   "source": [
    "for match in matches:\n",
    "    print((match))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['June', 'August', 'Dec']"
      ]
     },
     "execution_count": 28,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "regex = r\"([a-zA-Z]+) \\d+\"\n",
    "matches = re.findall(regex, \"June 24, August 9, Dec 12\")\n",
    "matches"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "June\n",
      "August\n",
      "Dec\n"
     ]
    }
   ],
   "source": [
    "for match in matches:\n",
    "    print((match))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 34,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<callable_iterator at 0x7ff61471faf0>"
      ]
     },
     "execution_count": 34,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "regex = r\"([a-zA-Z]+) \\d+\"\n",
    "matches = re.finditer(regex, \"June 24, August 9, Dec 12\")\n",
    "matches"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 35,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0\n",
      "7\n",
      "9\n",
      "17\n",
      "19\n",
      "25\n"
     ]
    }
   ],
   "source": [
    "for match in matches:\n",
    "    print(match.start())\n",
    "    print(match.end())"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Find and Replace Strings"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## re.sub(regex search, replacement_pattern, input_str, count, flags=0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 42,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'\\\\2 of \\\\1'"
      ]
     },
     "execution_count": 42,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "regex = r\"([a-zA-Z]+) (\\d+)\"\n",
    "test_str = \"June 24, August 9, Dec 12\"\n",
    "\n",
    "#\\2 means second group, \\1 means first group, GERNERAL \\x where x is the group\n",
    "replacement = r\"\\2 of \\1\"\n",
    "replacement"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 44,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "24 of June, 9 of August, 12 of Dec\n"
     ]
    }
   ],
   "source": [
    "print(re.sub(regex, replacement , \"June 24, August 9, Dec 12\"))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Re FLAGS"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# re.IGNORECASE"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### makes regex pattern case insensitive"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# re.MultiLINE"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### flag allows the start and end metacharacter to match at the beginning and end of each line instead of at the beginning and end of the whole input strins"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# re.DOTALL"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### allows the dot (.) metacharacter match all characters, including the newline character (\\n)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Compiling a pattern for performance "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## re.compile(regex search, flags=0)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 45,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<re.Match object; span=(0, 11), match='Hello World'>"
      ]
     },
     "execution_count": 45,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "regex = re.compile(r\"(\\w+) World\")\n",
    "test_str = \"Hello World is the easiest\"\n",
    "result = regex.search(test_str)\n",
    "\n",
    "result"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 47,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "['Hello', 'Bonjour']\n"
     ]
    }
   ],
   "source": [
    "res = regex.findall(\"Hello World, Bonjour World\")\n",
    "print(res)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 49,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Hello Earth, Bonjour Earth\n"
     ]
    }
   ],
   "source": [
    "print(regex.sub(r\"\\1 Earth\", \"Hello World, Bonjour World\"))"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.8.2"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 4
}