{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Markov Chains\n",
    "\n",
    "Play with this step by step walk through of how it works. Let's make a tiny chain."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from random import choice\n",
    "\n",
    "book = \"\"\"Would you could you in a house?\n",
    "Would you could you with a mouse?\n",
    "Would you could you in a box?\n",
    "Would you could you with a fox?\n",
    "Would you like green eggs and ham?\n",
    "Would you like them, Sam I am?\"\"\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Let's split the book into a list of words:\n",
    "words = book.split()\n",
    "words"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "def make_chains(text_string):\n",
    "    chains = {}\n",
    "    words = text_string\n",
    "    \n",
    "    # Loop over the words:\n",
    "    for n in range(len(text_string) - 2):\n",
    "        # Get the first and second words and put them into a tuple. They will act as keys in the chain:\n",
    "        key = (words[n], words[n+1],)\n",
    "        value = words[n+2]\n",
    "\n",
    "        # See if the key is already there\n",
    "        if key not in chains.keys():\n",
    "            # If it's not, initialize it's value to an empty list so we can insert words into it later\n",
    "            chains[key] = []\n",
    "\n",
    "        # Finally, add the next word to our keys\n",
    "        chains[key].append(value)\n",
    "\n",
    "    return chains\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "def make_text(chains):\n",
    "    \"\"\"Return text from chains.\"\"\"\n",
    "\n",
    "    # Choose a random key from the chain to start\n",
    "    key = choice(list(chains.keys()))\n",
    "    \n",
    "    # Create our new text that we can add to and return later\n",
    "    text = [key[0], key[1]]\n",
    "\n",
    "    # Choose a random value from the key in our chain\n",
    "    word = choice(chains[key])\n",
    "\n",
    "    # This loop will try to visit every key.\n",
    "    while word is not None:\n",
    "        # Form the next key\n",
    "        key = (key[1], word)\n",
    "        # Add the current word to the list\n",
    "        text.append(word)\n",
    "        # Get a new rand word from the new key\n",
    "        word = choice(chains[key])\n",
    "\n",
    "    # Finally return the new text!\n",
    "    return \" \".join(text)\n",
    "\n",
    "\n",
    "print(make_text(chains))\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
 "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": "3.7.0"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 2
}