02-intro-to-pandas-part-2-answers.ipynb

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    "(c) 2016 - present. Enplus Advisors, Inc."
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   "source": [
    "import numpy as np\n",
    "import pandas as pd"
   ]
  },
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    "df = pd.DataFrame({\n",
    "    'ticker': ['AAPL', 'AAPL', 'MSFT', 'IBM', 'YHOO'],\n",
    "    'date': ['2015-12-30', '2015-12-31', '2015-12-30', '2015-12-30', '2015-12-30'],\n",
    "    'open': [426.23, 427.81, 42.3, 101.65, 35.53]\n",
    "})"
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   "source": [
    "**Exercise:**\n",
    "\n",
    "* Select the `open` column as a `Series` using attribute lookup\n",
    "* Select the `open` column as a `Series` using `dict`-style lookup\n",
    "* Select the `date` column as a `DataFrame`"
   ]
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   "source": [
    "res1a = df.open\n",
    "res1b = df['open']\n",
    "res1c = df[['open']]"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
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   "source": [
    "**Exercise:**\n",
    "\n",
    "* Select all rows with the `AAPL` ticker and the `date` and `open`\n",
    "  columns.\n",
    "* Assign to the variable `df1` a new `DataFrame` with `ticker` as\n",
    "  the index.\n",
    "* Assign to the variable `df2` a new `DataFrame` with `date` as\n",
    "  the index. Create this `DataFrame` from `df1` with a single\n",
    "  statement.\n",
    "* Sort `df2` by the index values."
   ]
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   "cell_type": "code",
   "execution_count": 4,
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   "source": [
    "res2a = df.loc[df.ticker == 'AAPL', ['date', 'open']]\n",
    "df1 = df.set_index('ticker')\n",
    "df2 = df1.reset_index().set_index('date')"
   ]
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   "cell_type": "code",
   "execution_count": 5,
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   "source": [
    "df2_sorted = df2.sort_index()"
   ]
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   "cell_type": "markdown",
   "metadata": {
    "tags": [
     "exercise"
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   "source": [
    "**Exercise:**\n",
    "\n",
    "* Create a copy of `df` called `df3`. Add a new column of `NaNs` \n",
    "  to `df3` called `close`. Assign `close` the same value as `open`\n",
    "  for all `open` values greater than 100.\n",
    "* Sort `df3` by its `close` values."
   ]
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       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>ticker</th>\n",
       "      <th>date</th>\n",
       "      <th>open</th>\n",
       "      <th>close</th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>0</th>\n",
       "      <td>AAPL</td>\n",
       "      <td>2015-12-30</td>\n",
       "      <td>426.23</td>\n",
       "      <td>426.23</td>\n",
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       "      <th>1</th>\n",
       "      <td>AAPL</td>\n",
       "      <td>2015-12-31</td>\n",
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       "      <td>427.81</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>MSFT</td>\n",
       "      <td>2015-12-30</td>\n",
       "      <td>42.30</td>\n",
       "      <td>NaN</td>\n",
       "    </tr>\n",
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       "      <th>3</th>\n",
       "      <td>IBM</td>\n",
       "      <td>2015-12-30</td>\n",
       "      <td>101.65</td>\n",
       "      <td>101.65</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>4</th>\n",
       "      <td>YHOO</td>\n",
       "      <td>2015-12-30</td>\n",
       "      <td>35.53</td>\n",
       "      <td>NaN</td>\n",
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       "  ticker        date    open   close\n",
       "0   AAPL  2015-12-30  426.23  426.23\n",
       "1   AAPL  2015-12-31  427.81  427.81\n",
       "2   MSFT  2015-12-30   42.30     NaN\n",
       "3    IBM  2015-12-30  101.65  101.65\n",
       "4   YHOO  2015-12-30   35.53     NaN"
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   "source": [
    "df3 = df.copy()\n",
    "\n",
    "# this could be skipped from a functional standpoint, though\n",
    "# the instructions say to do it\n",
    "df3['close'] = np.nan \n",
    "\n",
    "gt100 = df3.open[df3.open > 100]\n",
    "df3.close = gt100 # you can use dot syntax b/c `close` already exists\n",
    "df3"
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