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    "# Programming and Data Analysis\n",
    "\n",
    "*Alla Tambovtseva, NRU HSE*\n",
    "\n",
    "\n",
    "## Seminar 2: lists"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Problem 0\n",
    "\n",
    "There are two lists `a` and `b` (see below).\n",
    "    \n",
    "1. Print the first element of `a`, the third element of `a`, and the last element of `a`.\n",
    "2. Add to the list `b` a number 7 (just write to the end).\n",
    "3. Change the fifth element of the list `a` to 8.\n",
    "4. Create the list `merged`, that includes all the elements of `a` and of `b`.\n",
    "5. Create the list `c` that can be obtained by changing the last element of `a` to 100. The list `a` should not be changed!"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "a = [1, 0, 9, 12, 18, 34, 89, 91, 33, 127]\n",
    "b = [2, 8, 9, 11, 76, 25, 44]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Problem 1\n",
    "\n",
    "There is a list of names:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "girls = [\"Ivetta\", \"Violetta\", \"Cassandra\", \n",
    "         \"Viktoria\", \"Amelia\", \"Rose\", \"Elizabeth\"] "
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Using `girls`, print the following lists:\n",
    "\n",
    "    [\"Violetta\", \"Cassandra\", \"Viktoria\", \"Amelia\"]\n",
    "    [\"Viktoria\", \"Amelia\", \"Rose\", \"Elizabeth\"]\n",
    "    [\"Ivetta\", \"Violetta\", \"Viktoria\", \"Amelia\"]\n",
    "    [\"Cassandra\", \"Amelia\", \"Rose\"]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Problem 2\n",
    "\n",
    "We have the list `L`. Print (one element from a new line): \n",
    "\n",
    "* all elements of `L`;\n",
    "* natural logarithms of elements of `L`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "L = [12, 3, 8, 125, 10, 98, 54, 199]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Change the fifth element of `L` to 0. Do the same operations as above. Why do you get such results?"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Problem 3\n",
    "\n",
    "In the list `age` we store respondents' age: \n",
    "\n",
    "    age = [24, 35, 42, 27, 45, 48, 33]\n",
    "    \n",
    "Create the list `age2` with values of respondents' age squared.\n",
    "\n",
    "**Hint:** use a for-loop."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Problem 4\n",
    "\n",
    "Python asks a user to enter an integer number $k$ from 1 to 10. Python takes this value $k$ and prints the $k$-th element of the list `numbers`, assuming that the numeration starts from 1.  "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "numbers = [1, 5, 6, 8, 10, 21, 25, 1, 0, -9, 9]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Example:**\n",
    "    \n",
    "*Input:*\n",
    "\n",
    "    Enter an integer from 1 to 10: 3\n",
    "    \n",
    "*Output:*\n",
    "\n",
    "    6"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Problem 5\n",
    "\n",
    "Explain, what the following code does and why it returns such results:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "5\n",
      "3\n",
      "5\n",
      "7\n"
     ]
    }
   ],
   "source": [
    "l = [1,2,3,4]\n",
    "\n",
    "for i in range(len(l)):\n",
    "    a = l[i] + l[i-1]\n",
    "    print(a)"
   ]
  }
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