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yijun_latitude
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2017.12.27 edit lesson 5
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‎python_basic/python_basic_lesson_05.ipynb‎

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"\n",
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"print(matches)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"---\n",
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"\n",
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"## 文件和目录操作之二\n",
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"\n",
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"读写文件是最常见的IO操作。Python内置了读写文件的函数，用法和C是兼容的。\n",
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"\n",
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"读写文件前，我们先必须了解一下，在磁盘上读写文件的功能都是由操作系统提供的，现代操作系统不允许普通的程序直接操作磁盘，所以，读写文件就是请求操作系统打开一个文件对象，然后，通过操作系统提供的接口从这个文件对象中读取数据，或者把数据写入这个文件对象。\n",
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"\n",
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"##### 读文件\n",
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"\n",
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"函数 `open()` 返回 文件对象，通常的用法需要两个参数：`open(filename, mode)`。分别是文件名和打开模式\n",
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"\n",
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"在做下面的例子前，我们要创建一个 `test.txt` 文件，并且保证其中的内容是如下样式，包含三行内容：\n",
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"\n",
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"> hello\n",
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"\n",
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"> hi\n",
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"\n",
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"> byebye\n",
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"\n",
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"文件保存在可以访问的目录，我这里就保存在和 notebook 同样的目录\n",
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"\n",
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"> 使用 jupyter 可以直接新建 Text File，来完成建立和编辑文本文件"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"import os\n",
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"\n",
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"# 获得当前路径\n",
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"cd = os.getcwd()\n",
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"\n",
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"print(cd)\n",
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"\n",
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"# 拼接完整文件名\n",
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"filename = os.path.join('/Users/Feng', 'test.txt')\n",
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"\n",
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"print(filename)\n",
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"\n",
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"try:\n",
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" # 打开文件\n",
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" f = open(filename, 'r')\n",
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" print(f.read())\n",
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"finally:\n",
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" if f:\n",
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" f.close()"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"# 简化调用方式\n",
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"# 省却了 try...finally，会有 with 来自动控制\n",
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"\n",
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"with open(filename, 'r') as f:\n",
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" print(f.read())"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"with open(filename, 'r') as f:\n",
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" lines = f.readlines()\n",
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"\n",
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"print(type(lines))\n",
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"print(lines)"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"for i in lines:\n",
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" print(i)"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"# 更简单的按行读取文件内容方法\n",
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"with open(filename, 'r') as f:\n",
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" for eachline in f:\n",
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" print(eachline)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"---\n",
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"\n",
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"##### 写文件\n",
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"\n",
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"写文件和读文件是一样的，唯一区别是调用 `open()` 函数时，传入标识符 `'w'` 或者 `'wb'` 表示写文本文件或写二进制文件。\n",
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"\n",
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"r 以读方式打开\n",
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"w 以写方式打开\n",
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"a 以追加模式打开（必要时候创建新文件）"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"# 写文件\n",
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"import os\n",
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"\n",
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"# 获得当前路径\n",
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"cd = os.getcwd()\n",
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"\n",
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"# 拼接完整文件名\n",
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"filename= os.path.join(cd, 'test2.txt')\n",
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"\n",
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"# 换行符\n",
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"br = os.linesep\n",
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"\n",
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"# 写文件\n",
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"with open(filename, 'w') as f:\n",
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" f.write('Hello, World!' + br)\n",
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" f.write('Hello, Shanghai!' + br)\n",
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" f.write('Hello, CHINA!' + br)\n",
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" \n",
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"with open(filename, 'r') as f:\n",
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" print(f.read())"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"##### 操作系统和文件系统差异处理\n",
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"\n",
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"`linesep` 文件中分隔行的字符串\n",
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"`path.sep` 分割文件路径名的字符串\n",
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"`curdir` 当前工作目录的字符串\n",
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"`pardir` 当前工作目录的父目录字符串"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"---\n",
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"\n",
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"##### 使用 glob 包查找文件\n",
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"\n",
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"glob 是 python 自己带的一个文件操作相关模块，很简洁，用它可以查找符合自己目的的文件，就类似于Windows下的文件搜索，而且也支持通配符: `*,?,[]` 这三个通配符，\\* 代表0个或多个字符，? 代表一个字符，[] 匹配指定范围内的字符，如[0-9]匹配数字。\n",
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"\n",
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"glob 的主要方法也叫 glob，该方法返回所有匹配的文件路径列表，该方法需要一个参数用来指定匹配的路径字符串"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"# 使用 glob 来遍历指定路径下的指定类型文件\n",
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"import glob\n",
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"\n",
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"# notebook 写法\n",
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"glob.glob('/Users/yijun/dev_python/*/*.py')\n",
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"\n",
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"# IDLE 写法\n",
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"l = glob.glob('/Users/yijun/dev_python/*/*.py')\n",
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"for i in l:\n",
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" print(i)"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"collapsed": true
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},
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"outputs": [],
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"source": [
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"l = glob.glob('/Users/yijun/dev_python/*/e2*.py')\n",
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"for i in l:\n",
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" print(i)"
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]
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}
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],
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"metadata": {
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"anaconda-cloud": {},
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"kernelspec": {
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"display_name": "Python 3",
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"display_name": "Python [default]",
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"language": "python",
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"name": "python3"
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},
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.4.5"
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"version": "3.5.2"
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}
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},
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"nbformat": 4,

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