{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Visualization in Python\n",
    "\n",
    "**Created and updated by** John C. S. Lui on August 14, 2020.\n",
    "\n",
    "**Important note:** *If you want to use and modify this notebook file, please acknowledge the author.*"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Data Visualization\n",
    "\n",
    "- Often, data analysts and scientists want to perform data visualization (e.g., plotting graphs, bar chart,..etc)\n",
    "- Python provides a **RICH** set of plotting functionalities\n",
    "- This lecture is meant to push you out of the Excel mindset, and introduce you to the popular Python library, e.g., mathplotlib\n",
    "- We will (a) download data, (b) parse the data from columns & rows to list of dictionary, (c) then render the data\n",
    "\n",
    "## Goals\n",
    "\n",
    "- Run a Python file from the command line\n",
    "- Make a simple graph\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Matplotlib\n",
    "\n",
    "- matplotlib is a popular scientific library that gives the developer tools to produce 2D figures\n",
    "- You need both numpy and matplotlib\n",
    "- Rich examples: <br>\n",
    "http://matplotlib.org/examples/index.html\n",
    "- GeoJSON is a derivative of JSON. It’s a data format for simple geological feature, including coordinate points.\n",
    "- GitHub has an awesome feature that allows folks to paste GeoJSON files into Gists, and renders as a map"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Plot1.py\n",
    "\n",
    "A simple x-y plot"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot1.py\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "X = np.linspace(-np.pi, np.pi, 256, endpoint=True)\n",
    "C, S = np.cos(X), np.sin(X)\n",
    "\n",
    "#print(X)\n",
    "#print(C)\n",
    "#print(S)\n",
    "\n",
    "plt.plot(X, C)       # plot C vs. X\n",
    "plt.plot(X, S)       # plot S vs. X\n",
    "\n",
    "plt.show()    # display all plots"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot2.py\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "# Create a figure of size 8x6 inches, 80 dots per inch\n",
    "plt.figure(figsize=(8, 6), dpi=80)\n",
    "\n",
    "# Create a new subplot from a grid of 1x1\n",
    "plt.subplot(1, 1, 1)\n",
    "\n",
    "X = np.linspace(-np.pi, np.pi, 256, endpoint=True)\n",
    "C, S = np.cos(X), np.sin(X)\n",
    "\n",
    "# Plot cosine with a blue continuous line of width 1 (pixels)\n",
    "plt.plot(X, C, color=\"blue\", linewidth=1.0, linestyle=\"-\")\n",
    "\n",
    "# Plot sine with a green continuous line of width 1 (pixels)\n",
    "plt.plot(X, S, color=\"green\", linewidth=1.0, linestyle=\"-\")\n",
    "\n",
    "# Set x limits\n",
    "plt.xlim(-4.0, 4.0)\n",
    "\n",
    "# Set x ticks\n",
    "plt.xticks(np.linspace(-4, 4, 9, endpoint=True))\n",
    "\n",
    "# Set y limits\n",
    "plt.ylim(-1.0, 1.0)\n",
    "\n",
    "# Set y ticks\n",
    "plt.yticks(np.linspace(-1, 1, 5, endpoint=True))\n",
    "\n",
    "# Save figure using 72 dots per inch\n",
    "plt.savefig(\"exercice_2.png\", dpi=72)\n",
    "\n",
    "# Show result on screen\n",
    "plt.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# ploy3.py\n",
    "\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "# Create a figure of size 8x6 inches, 80 dots per inch\n",
    "plt.figure(figsize=(10, 6), dpi=80)\n",
    "\n",
    "# Create a new subplot from a grid of 1x1\n",
    "plt.subplot(1, 1, 1)\n",
    "\n",
    "X = np.linspace(-np.pi, np.pi, 256, endpoint=True)\n",
    "C, S = np.cos(X), np.sin(X)\n",
    "\n",
    "# Plot cosine with a blue continuous line of width 1 (pixels)\n",
    "plt.plot(X, C, color=\"blue\", linewidth=2.5, linestyle=\"-\")\n",
    "\n",
    "# Plot sine with a green continuous line of width 1 (pixels)\n",
    "plt.plot(X, S, color=\"red\", linewidth=2.5, linestyle=\"-\")\n",
    "\n",
    "# Set x limits\n",
    "plt.xlim(-4.0, 4.0)\n",
    "\n",
    "# Set x ticks\n",
    "plt.xticks(np.linspace(-4, 4, 9, endpoint=True))\n",
    "\n",
    "# Set y limits\n",
    "plt.ylim(-1.0, 1.0)\n",
    "\n",
    "# Set y ticks\n",
    "plt.yticks(np.linspace(-1, 1, 5, endpoint=True))\n",
    "\n",
    "# Save figure using 72 dots per inch\n",
    "plt.savefig(\"exercice_2.png\", dpi=72)\n",
    "\n",
    "# Show result on screen\n",
    "plt.show()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot4.py\n",
    "\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "# Create a figure of size 8x6 inches, 80 dots per inch\n",
    "plt.figure(figsize=(10, 6), dpi=80)\n",
    "\n",
    "# Create a new subplot from a grid of 1x1\n",
    "plt.subplot(1, 1, 1)\n",
    "\n",
    "X = np.linspace(-np.pi, np.pi, 256, endpoint=True)\n",
    "C, S = np.cos(X), np.sin(X)\n",
    "\n",
    "# Plot cosine with a blue continuous line of width 1 (pixels)\n",
    "plt.plot(X, C, color=\"blue\", linewidth=2.5, linestyle=\"-\")\n",
    "\n",
    "# Plot sine with a green continuous line of width 1 (pixels)\n",
    "plt.plot(X, S, color=\"red\", linewidth=2.5, linestyle=\"-\")\n",
    "\n",
    "# Set x limits\n",
    "plt.xlim(X.min() * 1.1, X.max() * 1.1)\n",
    "\n",
    "# Set x ticks\n",
    "plt.xticks(np.linspace(-4, 4, 9, endpoint=True))\n",
    "\n",
    "# Set y limits\n",
    "plt.ylim(C.min() * 1.1, C.max() * 1.1)\n",
    "\n",
    "# Set y ticks\n",
    "plt.yticks(np.linspace(-1, 1, 5, endpoint=True))\n",
    "\n",
    "# Save figure using 72 dots per inch\n",
    "plt.savefig(\"exercice_2.png\", dpi=72)\n",
    "\n",
    "# Show result on screen\n",
    "plt.show()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot5.py\n",
    "\n",
    "\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "# Create a figure of size 8x6 inches, 80 dots per inch\n",
    "plt.figure(figsize=(10, 6), dpi=80)\n",
    "\n",
    "# Create a new subplot from a grid of 1x1\n",
    "plt.subplot(1, 1, 1)\n",
    "\n",
    "X = np.linspace(-np.pi, np.pi, 256, endpoint=True)\n",
    "C, S = np.cos(X), np.sin(X)\n",
    "\n",
    "# Plot cosine with a blue continuous line of width 1 (pixels)\n",
    "plt.plot(X, C, color=\"blue\", linewidth=2.5, linestyle=\"-\")\n",
    "\n",
    "# Plot sine with a green continuous line of width 1 (pixels)\n",
    "plt.plot(X, S, color=\"red\", linewidth=2.5, linestyle=\"-\")\n",
    "\n",
    "# Set x limits\n",
    "plt.xlim(X.min() * 1.1, X.max() * 1.1)\n",
    "\n",
    "# Set x ticks\n",
    "#plt.xticks(np.linspace(-4, 4, 9, endpoint=True))\n",
    "plt.xticks([-np.pi, -np.pi/2, 0, np.pi/2, np.pi])\n",
    "\n",
    "# Set y limits\n",
    "plt.ylim(C.min() * 1.1, C.max() * 1.1)\n",
    "\n",
    "# Set y ticks\n",
    "#plt.yticks(np.linspace(-1, 1, 5, endpoint=True))\n",
    "plt.yticks([-1, 0, +1])\n",
    "\n",
    "# Save figure using 72 dots per inch\n",
    "plt.savefig(\"exercice_2.png\", dpi=72)\n",
    "\n",
    "# Show result on screen\n",
    "plt.show()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot6.py\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "# Create a figure of size 8x6 inches, 80 dots per inch\n",
    "plt.figure(figsize=(10, 6), dpi=80)\n",
    "\n",
    "# Create a new subplot from a grid of 1x1\n",
    "plt.subplot(1, 1, 1)\n",
    "\n",
    "X = np.linspace(-np.pi, np.pi, 256, endpoint=True)\n",
    "C, S = np.cos(X), np.sin(X)\n",
    "\n",
    "# Plot cosine with a blue continuous line of width 1 (pixels)\n",
    "plt.plot(X, C, color=\"blue\", linewidth=2.5, linestyle=\"-\")\n",
    "\n",
    "# Plot sine with a green continuous line of width 1 (pixels)\n",
    "plt.plot(X, S, color=\"red\", linewidth=2.5, linestyle=\"-\")\n",
    "\n",
    "# Set x limits\n",
    "plt.xlim(X.min() * 1.1, X.max() * 1.1)\n",
    "\n",
    "# Set x ticks\n",
    "#plt.xticks(np.linspace(-4, 4, 9, endpoint=True))\n",
    "#plt.xticks([-np.pi, -np.pi/2, 0, np.pi/2, np.pi])\n",
    "plt.xticks([-np.pi, -np.pi/2, 0, np.pi/2, np.pi],\n",
    "          [r'$-\\pi$', r'$-\\pi/2$', r'$0$', r'$+\\pi/2$', r'$+\\pi$'])\n",
    "\n",
    "# Set y limits\n",
    "plt.ylim(C.min() * 1.1, C.max() * 1.1)\n",
    "\n",
    "# Set y ticks\n",
    "#plt.yticks(np.linspace(-1, 1, 5, endpoint=True))\n",
    "#plt.yticks([-1, 0, +1])\n",
    "plt.yticks([-1, 0, +1],\n",
    "          [r'$-1$', r'$0$', r'$+1$'])\n",
    "\n",
    "# Save figure using 72 dots per inch\n",
    "plt.savefig(\"exercice_2.png\", dpi=72)\n",
    "\n",
    "# Show result on screen\n",
    "plt.show()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot7.py\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "# Create a figure of size 8x6 inches, 80 dots per inch\n",
    "plt.figure(figsize=(10, 6), dpi=80)\n",
    "\n",
    "# Create a new subplot from a grid of 1x1\n",
    "plt.subplot(1, 1, 1)\n",
    "\n",
    "X = np.linspace(-np.pi, np.pi, 256, endpoint=True)\n",
    "C, S = np.cos(X), np.sin(X)\n",
    "\n",
    "# Plot cosine with a blue continuous line of width 1 (pixels)\n",
    "plt.plot(X, C, color=\"blue\", linewidth=2.5, linestyle=\"-\")\n",
    "\n",
    "# Plot sine with a green continuous line of width 1 (pixels)\n",
    "plt.plot(X, S, color=\"red\", linewidth=2.5, linestyle=\"-\")\n",
    "\n",
    "# Set x limits\n",
    "plt.xlim(X.min() * 1.1, X.max() * 1.1)\n",
    "\n",
    "# Set x ticks\n",
    "#plt.xticks(np.linspace(-4, 4, 9, endpoint=True))\n",
    "#plt.xticks([-np.pi, -np.pi/2, 0, np.pi/2, np.pi])\n",
    "plt.xticks([-np.pi, -np.pi/2, 0, np.pi/2, np.pi],\n",
    "          [r'$-\\pi$', r'$-\\pi/2$', r'$0$', r'$+\\pi/2$', r'$+\\pi$'])\n",
    "\n",
    "# Set y limits\n",
    "plt.ylim(C.min() * 1.1, C.max() * 1.1)\n",
    "\n",
    "# Set y ticks\n",
    "#plt.yticks(np.linspace(-1, 1, 5, endpoint=True))\n",
    "#plt.yticks([-1, 0, +1])\n",
    "plt.yticks([-1, 0, +1],\n",
    "          [r'$-1$', r'$0$', r'$+1$'])\n",
    "\n",
    "# Save figure using 72 dots per inch\n",
    "#plt.savefig(\"exercice_2.png\", dpi=72)\n",
    "\n",
    "ax = plt.gca()  # gca stands for 'get current axis'\n",
    "ax.spines['right'].set_color('none')\n",
    "ax.spines['top'].set_color('none')\n",
    "ax.xaxis.set_ticks_position('bottom')\n",
    "ax.spines['bottom'].set_position(('data',0))\n",
    "ax.yaxis.set_ticks_position('left')\n",
    "ax.spines['left'].set_position(('data',0))\n",
    "\n",
    "\n",
    "# Show result on screen\n",
    "plt.show()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot8.py\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "# Create a figure of size 8x6 inches, 80 dots per inch\n",
    "plt.figure(figsize=(10, 6), dpi=80)\n",
    "\n",
    "# Create a new subplot from a grid of 1x1\n",
    "plt.subplot(1, 1, 1)\n",
    "\n",
    "X = np.linspace(-np.pi, np.pi, 256, endpoint=True)\n",
    "C, S = np.cos(X), np.sin(X)\n",
    "\n",
    "# Plot cosine with a blue continuous line of width 1 (pixels)\n",
    "#plt.plot(X, C, color=\"blue\", linewidth=2.5, linestyle=\"-\")\n",
    "plt.plot(X, C, color=\"blue\", linewidth=2.5, linestyle=\"-\", label=\"cosine\")\n",
    "\n",
    "# Plot sine with a green continuous line of width 1 (pixels)\n",
    "#plt.plot(X, S, color=\"red\", linewidth=2.5, linestyle=\"-\")\n",
    "plt.plot(X, S, color=\"red\",  linewidth=2.5, linestyle=\"-\", label=\"sine\")\n",
    "\n",
    "\n",
    "# Set x limits\n",
    "plt.xlim(X.min() * 1.1, X.max() * 1.1)\n",
    "\n",
    "# Set x ticks\n",
    "#plt.xticks(np.linspace(-4, 4, 9, endpoint=True))\n",
    "#plt.xticks([-np.pi, -np.pi/2, 0, np.pi/2, np.pi])\n",
    "plt.xticks([-np.pi, -np.pi/2, 0, np.pi/2, np.pi],\n",
    "          [r'$-\\pi$', r'$-\\pi/2$', r'$0$', r'$+\\pi/2$', r'$+\\pi$'])\n",
    "\n",
    "# Set y limits\n",
    "plt.ylim(C.min() * 1.1, C.max() * 1.1)\n",
    "\n",
    "# Set y ticks\n",
    "#plt.yticks(np.linspace(-1, 1, 5, endpoint=True))\n",
    "#plt.yticks([-1, 0, +1])\n",
    "plt.yticks([-1, 0, +1],\n",
    "          [r'$-1$', r'$0$', r'$+1$'])\n",
    "\n",
    "# Save figure using 72 dots per inch\n",
    "#plt.savefig(\"exercice_2.png\", dpi=72)\n",
    "\n",
    "ax = plt.gca()  # gca stands for 'get current axis'\n",
    "ax.spines['right'].set_color('none')\n",
    "ax.spines['top'].set_color('none')\n",
    "ax.xaxis.set_ticks_position('bottom')\n",
    "ax.spines['bottom'].set_position(('data',0))\n",
    "ax.yaxis.set_ticks_position('left')\n",
    "ax.spines['left'].set_position(('data',0))\n",
    "\n",
    "# Print legend\n",
    "plt.legend(loc='upper right')\n",
    "\n",
    "# Show result on screen\n",
    "plt.show()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot9.py\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "# Create a figure of size 8x6 inches, 80 dots per inch\n",
    "plt.figure(figsize=(10, 6), dpi=80)\n",
    "\n",
    "# Create a new subplot from a grid of 1x1\n",
    "plt.subplot(1, 1, 1)\n",
    "\n",
    "X = np.linspace(-np.pi, np.pi, 256, endpoint=True)\n",
    "C, S = np.cos(X), np.sin(X)\n",
    "\n",
    "# Plot cosine with a blue continuous line of width 1 (pixels)\n",
    "#plt.plot(X, C, color=\"blue\", linewidth=2.5, linestyle=\"-\")\n",
    "plt.plot(X, C, color=\"blue\", linewidth=2.5, linestyle=\"-\", label=\"cosine\")\n",
    "\n",
    "# Plot sine with a green continuous line of width 1 (pixels)\n",
    "#plt.plot(X, S, color=\"red\", linewidth=2.5, linestyle=\"-\")\n",
    "plt.plot(X, S, color=\"red\",  linewidth=2.5, linestyle=\"-\", label=\"sine\")\n",
    "\n",
    "\n",
    "# Set x limits\n",
    "plt.xlim(X.min() * 1.1, X.max() * 1.1)\n",
    "\n",
    "# Set x ticks\n",
    "#plt.xticks(np.linspace(-4, 4, 9, endpoint=True))\n",
    "#plt.xticks([-np.pi, -np.pi/2, 0, np.pi/2, np.pi])\n",
    "plt.xticks([-np.pi, -np.pi/2, 0, np.pi/2, np.pi],\n",
    "          [r'$-\\pi$', r'$-\\pi/2$', r'$0$', r'$+\\pi/2$', r'$+\\pi$'])\n",
    "\n",
    "# Set y limits\n",
    "plt.ylim(C.min() * 1.1, C.max() * 1.1)\n",
    "\n",
    "# Set y ticks\n",
    "#plt.yticks(np.linspace(-1, 1, 5, endpoint=True))\n",
    "#plt.yticks([-1, 0, +1])\n",
    "plt.yticks([-1, 0, +1],\n",
    "          [r'$-1$', r'$0$', r'$+1$'])\n",
    "\n",
    "# Save figure using 72 dots per inch\n",
    "#plt.savefig(\"exercice_2.png\", dpi=72)\n",
    "\n",
    "ax = plt.gca()  # gca stands for 'get current axis'\n",
    "ax.spines['right'].set_color('none')\n",
    "ax.spines['top'].set_color('none')\n",
    "ax.xaxis.set_ticks_position('bottom')\n",
    "ax.spines['bottom'].set_position(('data',0))\n",
    "ax.yaxis.set_ticks_position('left')\n",
    "ax.spines['left'].set_position(('data',0))\n",
    "\n",
    "# annotate some points\n",
    "t = 2 * np.pi / 3\n",
    "plt.plot([t, t], [0, np.cos(t)], color='blue', linewidth=2.5, linestyle=\"--\")\n",
    "plt.scatter([t, ], [np.cos(t), ], 50, color='blue')\n",
    "\n",
    "plt.annotate(r'$sin(\\frac{2\\pi}{3})=\\frac{\\sqrt{3}}{2}$',\n",
    "             xy=(t, np.sin(t)), xycoords='data',\n",
    "             xytext=(+10, +30), textcoords='offset points', fontsize=16,\n",
    "             arrowprops=dict(arrowstyle=\"->\", connectionstyle=\"arc3,rad=.2\"))\n",
    "\n",
    "plt.plot([t, t],[0, np.sin(t)], color='red', linewidth=2.5, linestyle=\"--\")\n",
    "plt.scatter([t, ],[np.sin(t), ], 50, color='red')\n",
    "\n",
    "plt.annotate(r'$cos(\\frac{2\\pi}{3})=-\\frac{1}{2}$',\n",
    "             xy=(t, np.cos(t)), xycoords='data',\n",
    "             xytext=(-90, -50), textcoords='offset points', fontsize=16,\n",
    "             arrowprops=dict(arrowstyle=\"->\", connectionstyle=\"arc3,rad=.2\"))\n",
    "\n",
    "# Print legend\n",
    "plt.legend(loc='upper left')\n",
    "\n",
    "# Show result on screen\n",
    "plt.show()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot10.py\n",
    "\n",
    "\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "# Create a figure of size 8x6 inches, 80 dots per inch\n",
    "plt.figure(figsize=(10, 6), dpi=80)\n",
    "\n",
    "# Create a new subplot from a grid of 1x1\n",
    "plt.subplot(1, 1, 1)\n",
    "\n",
    "X = np.linspace(-np.pi, np.pi, 256, endpoint=True)\n",
    "C, S = np.cos(X), np.sin(X)\n",
    "\n",
    "# Plot cosine with a blue continuous line of width 1 (pixels)\n",
    "#plt.plot(X, C, color=\"blue\", linewidth=2.5, linestyle=\"-\")\n",
    "plt.plot(X, C, color=\"blue\", linewidth=2.5, linestyle=\"-\", label=\"cosine\")\n",
    "\n",
    "# Plot sine with a green continuous line of width 1 (pixels)\n",
    "#plt.plot(X, S, color=\"red\", linewidth=2.5, linestyle=\"-\")\n",
    "plt.plot(X, S, color=\"red\",  linewidth=2.5, linestyle=\"-\", label=\"sine\")\n",
    "\n",
    "\n",
    "# Set x limits\n",
    "plt.xlim(X.min() * 1.1, X.max() * 1.1)\n",
    "\n",
    "# Set x ticks\n",
    "#plt.xticks(np.linspace(-4, 4, 9, endpoint=True))\n",
    "#plt.xticks([-np.pi, -np.pi/2, 0, np.pi/2, np.pi])\n",
    "plt.xticks([-np.pi, -np.pi/2, 0, np.pi/2, np.pi],\n",
    "          [r'$-\\pi$', r'$-\\pi/2$', r'$0$', r'$+\\pi/2$', r'$+\\pi$'])\n",
    "\n",
    "# Set y limits\n",
    "plt.ylim(C.min() * 1.1, C.max() * 1.1)\n",
    "\n",
    "# Set y ticks\n",
    "#plt.yticks(np.linspace(-1, 1, 5, endpoint=True))\n",
    "#plt.yticks([-1, 0, +1])\n",
    "plt.yticks([-1, 0, +1],\n",
    "          [r'$-1$', r'$0$', r'$+1$'])\n",
    "\n",
    "# Save figure using 72 dots per inch\n",
    "#plt.savefig(\"exercice_2.png\", dpi=72)\n",
    "\n",
    "ax = plt.gca()  # gca stands for 'get current axis'\n",
    "ax.spines['right'].set_color('none')\n",
    "ax.spines['top'].set_color('none')\n",
    "ax.xaxis.set_ticks_position('bottom')\n",
    "ax.spines['bottom'].set_position(('data',0))\n",
    "ax.yaxis.set_ticks_position('left')\n",
    "ax.spines['left'].set_position(('data',0))\n",
    "\n",
    "# annotate some points\n",
    "t = 2 * np.pi / 3\n",
    "plt.plot([t, t], [0, np.cos(t)], color='blue', linewidth=2.5, linestyle=\"--\")\n",
    "plt.scatter([t, ], [np.cos(t), ], 50, color='blue')\n",
    "\n",
    "plt.annotate(r'$sin(\\frac{2\\pi}{3})=\\frac{\\sqrt{3}}{2}$',\n",
    "             xy=(t, np.sin(t)), xycoords='data',\n",
    "             xytext=(+10, +30), textcoords='offset points', fontsize=16,\n",
    "             arrowprops=dict(arrowstyle=\"->\", connectionstyle=\"arc3,rad=.2\"))\n",
    "\n",
    "plt.plot([t, t],[0, np.sin(t)], color='red', linewidth=2.5, linestyle=\"--\")\n",
    "plt.scatter([t, ],[np.sin(t), ], 50, color='red')\n",
    "\n",
    "plt.annotate(r'$cos(\\frac{2\\pi}{3})=-\\frac{1}{2}$',\n",
    "             xy=(t, np.cos(t)), xycoords='data',\n",
    "             xytext=(-90, -50), textcoords='offset points', fontsize=16,\n",
    "             arrowprops=dict(arrowstyle=\"->\", connectionstyle=\"arc3,rad=.2\"))\n",
    "\n",
    "# Print legend\n",
    "plt.legend(loc='upper left')\n",
    "\n",
    "# reset x-labels\n",
    "for label in ax.get_xticklabels() + ax.get_yticklabels():\n",
    "    label.set_fontsize(16)\n",
    "    label.set_bbox(dict(facecolor='white', edgecolor='None', alpha=0.65))\n",
    "\n",
    "# Show result on screen\n",
    "plt.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot11.py\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "n = 256\n",
    "X = np.linspace(-np.pi, np.pi, n, endpoint=True)\n",
    "Y = np.sin(2 * X)\n",
    "\n",
    "plt.axes([0.025, 0.025, 0.95, 0.95])\n",
    "\n",
    "plt.plot(X, Y + 1, color='blue', alpha=1.00)\n",
    "plt.fill_between(X, 1, Y + 1, color='blue', alpha=.25)\n",
    "\n",
    "plt.plot(X, Y - 1, color='blue', alpha=1.00)\n",
    "plt.fill_between(X, -1, Y - 1, (Y - 1) > -1, color='blue', alpha=.25)\n",
    "plt.fill_between(X, -1, Y - 1, (Y - 1) < -1, color='red',  alpha=.25)\n",
    "\n",
    "plt.xlim(-np.pi, np.pi)\n",
    "plt.xticks(())\n",
    "plt.ylim(-2.5, 2.5)\n",
    "plt.yticks(())\n",
    "\n",
    "plt.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot12.py\n",
    "\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "n = 1024\n",
    "X = np.random.normal(0, 1, n)\n",
    "Y = np.random.normal(0, 1, n)\n",
    "T = np.arctan2(Y, X)\n",
    "\n",
    "plt.axes([0.025, 0.025, 0.95, 0.95])\n",
    "plt.scatter(X, Y, s=75, c=T, alpha=.5)\n",
    "\n",
    "plt.xlim(-1.5, 1.5)\n",
    "plt.xticks(())\n",
    "plt.ylim(-1.5, 1.5)\n",
    "plt.yticks(())\n",
    "\n",
    "plt.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot13.py\n",
    "\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "n = 12\n",
    "X = np.arange(n)\n",
    "Y1 = (1 - X / float(n)) * np.random.uniform(0.5, 1.0, n)\n",
    "Y2 = (1 - X / float(n)) * np.random.uniform(0.5, 1.0, n)\n",
    "\n",
    "plt.axes([0.025, 0.025, 0.95, 0.95])\n",
    "plt.bar(X, +Y1, facecolor='#9999ff', edgecolor='white')\n",
    "plt.bar(X, -Y2, facecolor='#ff9999', edgecolor='white')\n",
    "\n",
    "for x, y in zip(X, Y1):\n",
    "    plt.text(x + 0.4, y + 0.05, '%.2f' % y, ha='center', va= 'bottom')\n",
    "\n",
    "for x, y in zip(X, Y2):\n",
    "    plt.text(x + 0.4, -y - 0.05, '%.2f' % y, ha='center', va= 'top')\n",
    "\n",
    "plt.xlim(-.5, n)\n",
    "plt.xticks(())\n",
    "plt.ylim(-1.25, 1.25)\n",
    "plt.yticks(())\n",
    "\n",
    "plt.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot14.py\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "def f(x,y):\n",
    "    return (1 - x / 2 + x**5 + y**3) * np.exp(-x**2 -y**2)\n",
    "\n",
    "n = 256\n",
    "x = np.linspace(-3, 3, n)\n",
    "y = np.linspace(-3, 3, n)\n",
    "X,Y = np.meshgrid(x, y)\n",
    "\n",
    "plt.axes([0.025, 0.025, 0.95, 0.95])\n",
    "\n",
    "plt.contourf(X, Y, f(X, Y), 8, alpha=.75, cmap=plt.cm.hot)\n",
    "C = plt.contour(X, Y, f(X, Y), 8, colors='black', linewidth=.5)\n",
    "plt.clabel(C, inline=1, fontsize=10)\n",
    "\n",
    "plt.xticks(())\n",
    "plt.yticks(())\n",
    "plt.show()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot15.py\n",
    "\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "\n",
    "n = 20\n",
    "Z = np.ones(n)\n",
    "Z[-1] *= 2\n",
    "\n",
    "plt.axes([0.025, 0.025, 0.95, 0.95])\n",
    "\n",
    "plt.pie(Z, explode=Z*.05, colors = ['%f' % (i/float(n)) for i in range(n)])\n",
    "plt.axis('equal')\n",
    "plt.xticks(())\n",
    "plt.yticks()\n",
    "\n",
    "plt.show()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# plot16.py\n",
    "\n",
    "import numpy as np\n",
    "import matplotlib.pyplot as plt\n",
    "from mpl_toolkits.mplot3d import Axes3D\n",
    "\n",
    "fig = plt.figure()\n",
    "ax = Axes3D(fig)\n",
    "X = np.arange(-4, 4, 0.25)\n",
    "Y = np.arange(-4, 4, 0.25)\n",
    "X, Y = np.meshgrid(X, Y)\n",
    "R = np.sqrt(X ** 2 + Y ** 2)\n",
    "Z = np.sin(R)\n",
    "\n",
    "ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=plt.cm.hot)\n",
    "ax.contourf(X, Y, Z, zdir='z', offset=-2, cmap=plt.cm.hot)\n",
    "ax.set_zlim(-2, 2)\n",
    "\n",
    "plt.show()\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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