{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Matplotlib 基础"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "在这节课中，我们将会学习到  Matplotlib 的相关内容。\n",
    "\n",
    "通过 Matplotlib，我们可以仅编写几行代码，就生成直方图，折现图，散点图等，高效美观的展示我们的数据。"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "\n",
    "\n",
    "导入 `matplotlib` 和 `numpy`："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "import matplotlib.pyplot as plt\n",
    "from numpy import *\n",
    "%matplotlib inline"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## plot 二维图"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "```python\n",
    "plt.plot(y)\n",
    "plt.plot(x, y)\n",
    "plt.plot(x, y, format_string)\n",
    "```\n",
    "\n",
    "只给定 `y` 值，默认以下标为 `x` 轴："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "x = linspace(0, 2 * pi, 50)\n",
    "plt.plot(sin(x));"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "给定 `x` 和 `y` 值："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "plt.plot(x, sin(x));"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "多条数据线："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "plt.plot(x, sin(x),\n",
    "    x, sin(2 * x));"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "使用字符串，给定线条参数："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "plt.plot(x, sin(x), 'r-^');"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "多线条："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "plt.plot(x, sin(x), 'b-o',\n",
    "    x, sin(2 * x), 'r-^');"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<img src='http://imgbed.momodel.cn/5cc1a0b8e3067ce9b6abf76f.jpg' width=16px height=16px>  **编程练习**\n",
    "\n",
    "在同一幅图中绘制 sin(x), sin(2\\*x), sin(3\\*x) 三条曲线。颜色分别为蓝色，红色，黄色。\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [],
   "source": [
    "# 请编写你的答案\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import matplotlib.pyplot as plt\n",
    "from numpy import *\n",
    "%matplotlib inline\n",
    "x = linspace(0, 2 * pi, 50)\n",
    "plt.plot(x, sin(x), 'b', x, sin(2 * x), 'r', x, sin(3 * x), 'y');\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## scatter 散点图"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "```python\n",
    "scatter(x, y)\n",
    "scatter(x, y, size)\n",
    "scatter(x, y, size, color)\n",
    "```\n",
    "\n",
    "假设我们想画二维散点图："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "plt.plot(x, sin(x), 'bo');"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "可以使用 `scatter` 达到同样的效果："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "plt.scatter(x, sin(x));"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "x = random.rand(200)\n",
    "y = random.rand(200)\n",
    "size = random.rand(200) * 30\n",
    "color = random.rand(200)\n",
    "plt.scatter(x, y, size, color)\n",
    "# 显示颜色条\n",
    "plt.colorbar();"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<img src='http://imgbed.momodel.cn/5cc1a0b8e3067ce9b6abf76f.jpg' width=16px height=16px>  **编程练习**\n",
    "\n",
    "要求：使用 scatter 绘制 sin(x)的二维散点图，把颜色设置为红色，散点形式设置为三角形."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 请编写你的答案\n",
    "\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import matplotlib.pyplot as plt\n",
    "x = linspace(0, 10, 30)\n",
    "plt.scatter(x, sin(x), marker='^', color='r');\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 多图"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "使用figure()命令产生新的图像："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "t = linspace(0, 2*pi, 50)\n",
    "x = sin(t)\n",
    "y = cos(t)\n",
    "plt.figure()\n",
    "plt.plot(x)\n",
    "plt.figure()\n",
    "plt.plot(y);"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "或者使用 `subplot` 在一幅图中画多幅子图：\n",
    "\n",
    "    subplot(row, column, index)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "plt.subplot(1, 2, 1)\n",
    "plt.plot(x)\n",
    "plt.subplot(1, 2, 2)\n",
    "plt.plot(y);"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<img src='http://imgbed.momodel.cn/5cc1a0b8e3067ce9b6abf76f.jpg' width=16px height=16px>  **编程练习**\n",
    "\n",
    "要求：在上下排布的2个子图中，显示sin(x)和cos(x)的图像，请编写代码实现。"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 请编写你的答案\n",
    "\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "fig = plt.figure()\n",
    "plt.subplot(2, 1, 1)\n",
    "plt.plot(x)\n",
    "plt.subplot(2, 1, 2)\n",
    "plt.plot(y);\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 向图中添加数据"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "默认多次 `plot` 会叠加："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "plt.plot(x)\n",
    "plt.plot(y);"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 标签"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "可以在 `plot` 中加入 `label` ，使用 `legend` 加上图例："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "plt.plot(x, label='sin')\n",
    "plt.plot(y, label='cos')\n",
    "plt.legend();"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "或者直接在 `legend`中加入："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "plt.plot(x)\n",
    "plt.plot(y)\n",
    "plt.legend(['sin', 'cos']);"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 坐标轴，标题，网格"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "可以设置坐标轴的标签和标题："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "x = linspace(0, 2 * pi, 50)\n",
    "plt.plot(x, sin(x))\n",
    "plt.xlabel('radians')\n",
    "# 可以设置字体大小\n",
    "plt.ylabel('amplitude', fontsize='large')\n",
    "plt.title('Sin(x)');"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "用 'grid()' 来显示网格："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "plt.plot(x, sin(x))\n",
    "plt.xlabel('radians')\n",
    "plt.ylabel('amplitude', fontsize='large')\n",
    "plt.title('Sin(x)')\n",
    "plt.grid();"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<img src='http://imgbed.momodel.cn/5cc1a0b8e3067ce9b6abf76f.jpg' width=16px height=16px>  **编程练习**\n",
    "\n",
    "要求：绘制 cos(x) 的图，包含坐标轴、标题和网格。"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 请编写你的答案\n",
    "\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "plt.plot(x, cos(x))\n",
    "plt.xlabel('radians')\n",
    "plt.ylabel('amplitude', fontsize='large')\n",
    "plt.title('Cos(x)')\n",
    "plt.grid();\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 直方图"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "从高斯分布随机生成1000个点得到的直方图："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "plt.hist(np.random.randn(1000));"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "更多例子请参考下列网站：\n",
    "\n",
    "http://matplotlib.org/gallery.html"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<img src='http://imgbed.momodel.cn/5cc1a0b8e3067ce9b6abf76f.jpg' width=16px height=16px>  **编程练习**\n",
    "\n",
    "要求： 已知某商店出售 3 种水果，当天的营业额分别为苹果：100，香蕉：200，葡萄：250，请绘制饼图，显示三种水果的占比。"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 请编写你的答案\n",
    "\n",
    "\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "labels = [u'苹果',u'香蕉',u'葡萄'] #定义标签\n",
    "sizes = [100,200,300,] #每块值\n",
    "plt.pie(sizes, labels=labels, autopct = '%3.2f%%');\n"
   ]
  }
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