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  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Python для сбора и анализа данных\n",
    "\n",
    "*Алла Тамбовцева, НИУ ВШЭ*\n",
    "\n",
    "*Данный ноутбук частично основан на [лекции](http://nbviewer.math-hse.info/github/ischurov/pythonhse/blob/master/Lecture%202.ipynb) Щурова И.В., курс «Программирование на языке Python для сбора и анализа данных» (НИУ ВШЭ).*"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Списки и цикл `for`"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Знакомство со списками"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Создадим список значений возраста респондентов, список `age`:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "age = [23, 25, 32, 48, 19] # возраст\n",
    "age"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "name = [\"Анна\", \"Виктор\", \"Дмитрий\", \"Алёна\", \"Павел\"] # имена"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "mix = [23, 25, \"нет ответа\", 32, \"нет ответа\"] # все вместе"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "type(mix)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "len(age) # пять элементов"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "empty = []\n",
    "len(empty)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(age[0]) # первый элемент age\n",
    "print(age[1])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(age[7])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(age[-1]) # последний элемент - он же первый с конца"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "age[-2]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Изменение и добавление элементов"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "age[0] = 32 # заменили первый элемент на 32\n",
    "age"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "nums = [1, 5, 8, 9]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "nums.append(10) # добавили 10\n",
    "nums"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "nums.extend([12, 13]) # добавили 12 и 13\n",
    "nums"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "L = []\n",
    "L.append(6)\n",
    "L.append(8)\n",
    "L"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "nums.extend(6) # случай 1: один элемент не добавится"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "[1, 2, 3] + [9, 10]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Срезы (slices)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(age) "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "age[1:3] # левый конец включается, а правый нет"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(age[1:])\n",
    "print(age[3:])\n",
    "print(age[:2])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "age[:] # опускаем все индексы"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "age[2:2] # пустой срез"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Изменение списков"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "На данный момент мы достаточно хорошо познакомились со списками. Но списки не так просты, как кажется. Давайте попробуем сделать следующее: скопировать один список в другой путем присваивания."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "L1 = [1, 8, 9, 4]\n",
    "L2 = L1 # сохранили список L1 в L2\n",
    "\n",
    "print(L1)\n",
    "print(L2)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "L2[3] = 5\n",
    "print(L2)\n",
    "print(L1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# дубль два\n",
    "L1 = [1, 8, 9, 4]\n",
    "L2 = L1.copy()\n",
    "\n",
    "# теперь делаем что угодно\n",
    "\n",
    "L2[3] = 100\n",
    "\n",
    "print(L1)\n",
    "print(L2) # все нормально"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Цикл `for`\n",
    "\n",
    "Раз есть списки, хочется научиться пробегаться по их элементам. Например, выводить на экран не весь список `age` сразу, а постепенно, каждый элемент с новой строчки. Для этого есть циклы. Рассмотрим цикл `for`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "for i in age:\n",
    "    print(i)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "list1 = [1, 3, 5, 9]\n",
    "list2 = [] # новый список\n",
    "\n",
    "for l in list1:\n",
    "    list2.append(l * 2) # добавляем в него значения из list1, умноженные на 2\n",
    "print(list2)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# создадим список с номерами дней\n",
    "\n",
    "days = [2, 3, 4, 5, 6, 7, 8, 9, 10]\n",
    "\n",
    "# начальное значение времени, которое питон проводит на солнце\n",
    "\n",
    "time = 1\n",
    "\n",
    "print(1, time)\n",
    "\n",
    "# теперь будем изменять значение time в цикле\n",
    "# и выводить на экран номер дня и время\n",
    "\n",
    "for d in days:\n",
    "    time = time + 3\n",
    "    print(d, time)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Функция `range()`"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# пример\n",
    "\n",
    "for j in range(0, 6):\n",
    "    print(j)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "time = 1\n",
    "print(1, time)\n",
    "\n",
    "for d in range(2, 11):\n",
    "    time = time + 3\n",
    "    print(d, time)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "range(0, 3) # не поспоришь, но бесполезно"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "list(range(0, 3)) # значения внутри range"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "list(range(5))"
   ]
  }
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