{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 下載 myfun.py\n",
    "!wget \"https://raw.githubusercontent.com/TA-aiacademy/course_3.0/ML/02_ML/part3/Chapter3/myfun.py\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import numpy as np\n",
    "import pandas as pd\n",
    "\n",
    "from sklearn.datasets import make_blobs\n",
    "from sklearn.neighbors import KNeighborsClassifier\n",
    "from myfun import plot_decision_regions\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "%matplotlib inline"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# 調整K觀察結果"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# make 3-class dataset for classification\n",
    "centers = [[0, 0], [3.5, 0]]\n",
    "X, y = make_blobs(n_samples=100, centers=centers, random_state=40)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "color = \"rb\"\n",
    "color = [color[y[i]] for i in range(len(y))]\n",
    "plt.scatter(X[:, 0], X[:, 1], c=color)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "def knn_example(plot_dict, X, y, k):\n",
    "    # create model\n",
    "    model = KNeighborsClassifier(n_neighbors=k)\n",
    "\n",
    "    # training\n",
    "    model.fit(X, y)\n",
    "\n",
    "    # Plot the decision boundary. For that, we will assign a color to each\n",
    "    if k in plot_dict:\n",
    "        plt.subplot(plot_dict[k])\n",
    "        plt.tight_layout()\n",
    "        plot_decision_regions(X, y, model)\n",
    "        plt.title('Plot for K: %d' % k)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "plt.figure(figsize=(8.5, 6))\n",
    "\n",
    "# 調整 K\n",
    "plot_dict = {1: 231, 2: 232, 3: 233, 4: 234, 5: 235, 6: 236}\n",
    "for i in plot_dict:\n",
    "    knn_example(plot_dict, X, y, i)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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