{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Simple while loop"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "n = 23\n",
    "r = True\n",
    "\n",
    "while r:\n",
    "    guess= int(input('Enter an integer: '))\n",
    "    \n",
    "    if guess == n:\n",
    "        print('yes')\n",
    "        r = False\n",
    "    elif guess < n:\n",
    "        print('no')\n",
    "    else:\n",
    "        print('no1')\n",
    "else:\n",
    "    print('done')\n",
    "    \n",
    "print('yes done')        "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Simple backup"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "created today\n",
      "Zip command is:\n",
      "zip -r /home/akash/funny3zip/20200624/145038.zip / h o m e / a k a s h / f u n n y 3\n",
      "Running:\n",
      "Backup FAILED\n"
     ]
    }
   ],
   "source": [
    "import os\n",
    "import time\n",
    "\n",
    "source = '/home/akash/funny3'\n",
    "\n",
    "target = '/home/akash/funny3zip'\n",
    "\n",
    "if not os.path.exists(target): \n",
    "    os.mkdir(target)\n",
    "    \n",
    "today = target + os.sep + time.strftime('%Y%m%d')\n",
    "\n",
    "now = time.strftime('%H%M%S')\n",
    "\n",
    "target = today+os.sep+now+'.zip'\n",
    "\n",
    "if not os.path.exists(today): \n",
    "    os.mkdir(today)\n",
    "    print('created today')\n",
    "    \n",
    "zip_command = \"zip -r {0} {1}\".format(target, ' '.join(source)) \n",
    "# Run the backup \n",
    "print (\"Zip command is:\")\n",
    "print(zip_command)\n",
    "print(\"Running:\")\n",
    "if os.system(zip_command) == 0:\n",
    "    print('Successful backup to', target)\n",
    "else:\n",
    "    print('Backup FAILED')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## A simple class"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [],
   "source": [
    "class Robot:\n",
    "    \n",
    "    # a class variable\n",
    "    \n",
    "    population = 0\n",
    "    \n",
    "    def __init__(self, name):\n",
    "        # initialized the data\n",
    "        self.name = name\n",
    "        print(\"(Initializing {})\".format(self.name))\n",
    "        \n",
    "        Robot.population += 1\n",
    "        \n",
    "    def die(self):\n",
    "        # Dying\n",
    "        \n",
    "        print(\"{} is being destroyed\".format(self.name))\n",
    "        \n",
    "        Robot.population -= 1\n",
    "        \n",
    "        if Robot.population == 0:\n",
    "            print(\"{} was the last one\".format(self.name))\n",
    "        else:\n",
    "            print(\"There are still {:d} robots working\".format(Robot.population))\n",
    "            \n",
    "    def say_hi(self):\n",
    "        # greeting\n",
    "        \n",
    "        print(\"Greetings, i am\".format(self.name))\n",
    "        \n",
    "    @classmethod\n",
    "    def how_many(cls):\n",
    "        ## prints current population\n",
    "        print(\" we have {:d} robots. \". format(cls.population))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(Initializing R2)\n",
      "Greetings, i am\n",
      " we have 1 robots. \n",
      "(Initializing R3)\n",
      "Greetings, i am\n",
      " we have 2 robots. \n",
      "they can work now\n",
      "destroyinnng...\n",
      "R2 is being destroyed\n",
      "There are still 1 robots working\n",
      "R3 is being destroyed\n",
      "R3 was the last one\n",
      " we have 0 robots. \n"
     ]
    }
   ],
   "source": [
    "droid1 = Robot(\"R2\")\n",
    "droid1.say_hi()\n",
    "Robot.how_many()\n",
    "\n",
    "droid2 = Robot(\"R3\")\n",
    "droid2.say_hi()\n",
    "Robot.how_many()\n",
    "\n",
    "print(\"they can work now\")\n",
    "\n",
    "print(\"destroyinnng...\")\n",
    "\n",
    "droid1.die()\n",
    "droid2.die()\n",
    "\n",
    "Robot.how_many()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Inheritance"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 42,
   "metadata": {},
   "outputs": [],
   "source": [
    "class SchoolMember:\n",
    "    def __init__(self, name, age):\n",
    "        self.name = name\n",
    "        self.age = age\n",
    "        print('Initialized SchoolMember: {})'.format(self.name))\n",
    "        \n",
    "    def tell(self):\n",
    "        '''Tell my details.''' \n",
    "        print('Name:\"{}\" Age:\"{}\"'.format(self.name, self.age))\n",
    "        \n",
    "        \n",
    "class Teacher(SchoolMember):\n",
    "    \n",
    "    def __init__(self, name, age, salary):\n",
    "        SchoolMember.__init__(self, name, age)\n",
    "        self.salary = salary\n",
    "        print('Initialized Teacher: {})'.format(self.name))\n",
    "              \n",
    "    def tell(self):\n",
    "        SchoolMember.tell(self)\n",
    "        print('Salary: \"{:d}\"'.format(self.salary))\n",
    "\n",
    "class Student(SchoolMember):\n",
    "    \n",
    "    def __init__(self, name, age, marks):\n",
    "        SchoolMember.__init__(self, name, age)\n",
    "        self.marks = marks\n",
    "        print('Initialized Student: {})'.format(self.name))\n",
    "              \n",
    "    def tell(self):\n",
    "        \n",
    "        SchoolMember.tell(self)\n",
    "        print('Marks: \"{:d}\"'.format(self.marks)) "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 44,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Initialized SchoolMember: A)\n",
      "Initialized Teacher: A)\n",
      "Initialized SchoolMember: me)\n",
      "Initialized Student: me)\n",
      "Name:\"A\" Age:\"40\"\n",
      "Salary: \"20000\"\n",
      "Name:\"me\" Age:\"25\"\n",
      "Marks: \"75\"\n"
     ]
    }
   ],
   "source": [
    "t = Teacher('A', 40, 20000)\n",
    "\n",
    "s = Student('me', 25, 75)\n",
    "\n",
    "m = [t, s]\n",
    "\n",
    "for members in m:\n",
    "    members.tell()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Exceptions"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 47,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "enter-->sd\n",
      "you entered sd\n"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    text = input(\"enter-->\")\n",
    "except EOFError:\n",
    "    print('why eof')\n",
    "else:\n",
    "    print(\"you entered {}\".format(text))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Finally"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import sys\n",
    "import time \n",
    "f = None\n",
    "\n",
    "try:\n",
    "    f = open(\"poem.txt\") # Our usual file-reading idiom \n",
    "    while True:\n",
    "        line = f.readline()\n",
    "        if len(line) == 0:\n",
    "            break\n",
    "        print line, sys.stdout.flush()\n",
    "        print \"Press ctrl+c now\" # To make sure it runs for a while\n",
    "        time.sleep(2) \n",
    "except IOError:\n",
    "    print \"Could not find file poem.txt\" \n",
    "except KeyboardInterrupt:\n",
    "    print \"!! You cancelled the reading from the file.\"\n",
    "finally: \n",
    "    if f: f.close()\n",
    "        print \"(Cleaning up: Closed the file)\""
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## With statement"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "with open('file.txt') as w:\n",
    "    for line in w:\n",
    "        print(line)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Standard Libraries"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 49,
   "metadata": {},
   "outputs": [],
   "source": [
    "## sys module - system specific \n",
    "\n",
    "# print(sys.argv)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 50,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "sys.version_info(major=3, minor=7, micro=3, releaselevel='final', serial=0)"
      ]
     },
     "execution_count": 50,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "sys.version_info"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "## Loggin module\n",
    "\n",
    "\n",
    "import os, platform, logging\n",
    "\n",
    "if platform.platform().startswith('Windows'):\n",
    "    logging_file = os.path.join(os.getenv('HOMEDRIVE'), os.getenv('HOMEPATH'), 'test.log')\n",
    "else: logging_file = os.path.join(os.getenv('HOME'), 'test.log')\n",
    "\n",
    "print \"Logging to\", logging_file\n",
    "\n",
    "logging.basicConfig( level=logging.DEBUG, format='%(asctime)s : %(levelname)s : %(message)s', filename = logging_file, filemode = 'w', )\n",
    "\n",
    "logging.debug(\"Start of the program\")\n",
    "logging.info(\"Doing something\")\n",
    "logging.warning(\"Dying now\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Lambda Forms"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 51,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[{'x': 4, 'y': 1}, {'x': 2, 'y': 3}]\n"
     ]
    }
   ],
   "source": [
    "points = [ { 'x' : 2, 'y' : 3 }, { 'x' : 4, 'y' : 1 } ]\n",
    "points.sort(key=lambda i : i['y'])\n",
    "print(points)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### List Comprehensions"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 52,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[6, 8]"
      ]
     },
     "execution_count": 52,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "listone = [2, 3, 4]\n",
    "listtwo = [2*i for i in listone if i > 2]\n",
    "listtwo"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Assert"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 53,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'item'"
      ]
     },
     "execution_count": 53,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "mylist = ['item']\n",
    "assert len(mylist) >= 1\n",
    "mylist.pop()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 54,
   "metadata": {},
   "outputs": [
    {
     "ename": "AssertionError",
     "evalue": "",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mAssertionError\u001b[0m                            Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-54-927142ca25aa>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0;32massert\u001b[0m \u001b[0mlen\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mmylist\u001b[0m\u001b[0;34m)\u001b[0m \u001b[0;34m>=\u001b[0m \u001b[0;36m1\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mAssertionError\u001b[0m: "
     ]
    }
   ],
   "source": [
    "assert len(mylist) >= 1"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Decorators"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from time import sleep\n",
    "from functools import wraps\n",
    "import logging\n",
    "logging.basicConfig()\n",
    "log = logging.getLogger(\"retry\")\n",
    "\n",
    "\n",
    "def retry(f):\n",
    "    @wraps(f)\n",
    "    def wrapped_f(*args, **kwargs):\n",
    "        MAX_ATTEMPTS = 5\n",
    "        for attempt in range(1, MAX_ATTEMPTS + 1):\n",
    "            try:\n",
    "                return f(*args, **kwargs)\n",
    "            except:\n",
    "                log.exception(\"Attempt %s/%s failed : %s\", attempt, MAX_ATTEMPTS, (args, kwargs))\n",
    "                sleep(10 * attempt)\n",
    "            log.critical(\"All %s attempts failed : %s\", MAX_ATTEMPTS, (args, kwargs))\n",
    "        return wrapped_f\n",
    "    counter = 0\n",
    "\n",
    "\n",
    "    \n",
    "@retry\n",
    "def save_to_database(arg):\n",
    "    print \"Write to a database or make a network call or etc.\"\n",
    "    print \"This will be automatically retried if exception is thrown.\"\n",
    "    global counter\n",
    "    counter += 1 # This will throw an exception in the first call # And will work fine in the second call (i.e. a retry)\n",
    "    if counter < 2:\n",
    "        raise ValueError(arg)\n",
    "    \n",
    "if __name__ == '__main__':\n",
    "    save_to_database(\"Some bad value\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Command line arguments"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#!/usr/bin/python\n",
    "\n",
    "import sys\n",
    "\n",
    "# it's easy to print this list of course:\n",
    "print(sys.argv)\n",
    "\n",
    "# or it can be iterated via a for loop:\n",
    "\n",
    "for i in range(len(sys.argv)):\n",
    "    if i == 0:\n",
    "        print(\"Function name: %s\" % sys.argv[0])\n",
    "    else:\n",
    "        print(\"%d. argument: %s\" % (i,sys.argv[i]))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "## OUTPUT \n",
    "\n",
    "$ python arguments.py arg1 arg2\n",
    "['arguments.py', 'arg1', 'arg2']\n",
    "Function name: arguments.py\n",
    "1. argument: arg1\n",
    "2. argument: arg2\n",
    "$"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### System programming and Python"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "## Packages:\n",
    "\n",
    "os\n",
    "platform\n",
    "subprocess\n",
    "shutils\n",
    "glob\n",
    "sys"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 55,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "posix\n"
     ]
    }
   ],
   "source": [
    "import os\n",
    "\n",
    "print(os.name)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "These names define the following operating systems:\n",
    "\n",
    "posix\n",
    "Unix-like operating systems like Unix, Linux, BSD, Minix and others.\n",
    "nt\n",
    "Windows systems like \"Windows 10\", \"Windows 8.1\", \"Windows 8\", \"Windows 7\" and so on.\n",
    "java\n",
    "Java operating system."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "## Other common commands:\n",
    "\n",
    "print(os.getcwd())\n",
    "os.chdir(\"\") ## Changes to the path mentioned\n",
    "print(os.getcwd())\n",
    "\n",
    "print(os.listdir()) ## names of the files of directory"
   ]
  }
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