diff --git a/notebooks/18-Missing-Values.ipynb b/notebooks/18-Missing-Values.ipynb
new file mode 100644
index 0000000..0e9f950
--- /dev/null
+++ b/notebooks/18-Missing-Values.ipynb
@@ -0,0 +1,711 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "import pandas as pd\n",
+    "import numpy as np"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style>\n",
+       "    .dataframe thead tr:only-child th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: left;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>first_name</th>\n",
+       "      <th>last_name</th>\n",
+       "      <th>score</th>\n",
+       "      <th>year</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>Tripoli</th>\n",
+       "      <td>Noureddin</td>\n",
+       "      <td>Sadawi</td>\n",
+       "      <td>422</td>\n",
+       "      <td>2015</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Birmingham</th>\n",
+       "      <td>Josef</td>\n",
+       "      <td>Baker</td>\n",
+       "      <td>322</td>\n",
+       "      <td>2009</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>London</th>\n",
+       "      <td>Mike</td>\n",
+       "      <td>Brooks</td>\n",
+       "      <td>233</td>\n",
+       "      <td>2013</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Islamabad</th>\n",
+       "      <td>Ali</td>\n",
+       "      <td>Shah</td>\n",
+       "      <td>223</td>\n",
+       "      <td>2016</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>New York</th>\n",
+       "      <td>Luke</td>\n",
+       "      <td>Brown</td>\n",
+       "      <td>401</td>\n",
+       "      <td>2014</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           first_name last_name  score  year\n",
+       "Tripoli     Noureddin    Sadawi    422  2015\n",
+       "Birmingham      Josef     Baker    322  2009\n",
+       "London           Mike    Brooks    233  2013\n",
+       "Islamabad         Ali      Shah    223  2016\n",
+       "New York         Luke     Brown    401  2014"
+      ]
+     },
+     "execution_count": 3,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "# here we create a simple dataframe\n",
+    "raw_data = {'first_name': ['Noureddin', 'Josef', 'Mike', 'Ali', 'Luke'],\n",
+    "        'last_name': ['Sadawi', 'Baker', 'Brooks', 'Shah', 'Brown'],\n",
+    "        'year': [2015,2009,2013,2016,2014],\n",
+    "        'score': [422,322,233,223,401]}\n",
+    "df = pd.DataFrame(raw_data, index = ['Tripoli', 'Birmingham', 'London', 'Islamabad', 'New York'])\n",
+    "df"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "m = df[df < 240]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 15,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style>\n",
+       "    .dataframe thead tr:only-child th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: left;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>first_name</th>\n",
+       "      <th>last_name</th>\n",
+       "      <th>score</th>\n",
+       "      <th>year</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>Tripoli</th>\n",
+       "      <td>Noureddin</td>\n",
+       "      <td>Sadawi</td>\n",
+       "      <td>1.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Birmingham</th>\n",
+       "      <td>Josef</td>\n",
+       "      <td>Baker</td>\n",
+       "      <td>1.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>London</th>\n",
+       "      <td>Mike</td>\n",
+       "      <td>Brooks</td>\n",
+       "      <td>233.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Islamabad</th>\n",
+       "      <td>Ali</td>\n",
+       "      <td>Shah</td>\n",
+       "      <td>223.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>New York</th>\n",
+       "      <td>Luke</td>\n",
+       "      <td>Brown</td>\n",
+       "      <td>1.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           first_name last_name  score  year\n",
+       "Tripoli     Noureddin    Sadawi    1.0   1.0\n",
+       "Birmingham      Josef     Baker    1.0   1.0\n",
+       "London           Mike    Brooks  233.0   1.0\n",
+       "Islamabad         Ali      Shah  223.0   1.0\n",
+       "New York         Luke     Brown    1.0   1.0"
+      ]
+     },
+     "execution_count": 15,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "# m is a dataframe that contains missing values ,, the NaNs\n",
+    "m"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 6,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "<bound method DataFrame.dropna of            first_name last_name  score  year\n",
+       "Tripoli     Noureddin    Sadawi    NaN   NaN\n",
+       "Birmingham      Josef     Baker    NaN   NaN\n",
+       "London           Mike    Brooks  233.0   NaN\n",
+       "Islamabad         Ali      Shah  223.0   NaN\n",
+       "New York         Luke     Brown    NaN   NaN>"
+      ]
+     },
+     "execution_count": 6,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "m.dropna"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style>\n",
+       "    .dataframe thead tr:only-child th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: left;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>first_name</th>\n",
+       "      <th>last_name</th>\n",
+       "      <th>score</th>\n",
+       "      <th>year</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>Tripoli</th>\n",
+       "      <td>Noureddin</td>\n",
+       "      <td>Sadawi</td>\n",
+       "      <td>NaN</td>\n",
+       "      <td>NaN</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Birmingham</th>\n",
+       "      <td>Josef</td>\n",
+       "      <td>Baker</td>\n",
+       "      <td>NaN</td>\n",
+       "      <td>NaN</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>London</th>\n",
+       "      <td>Mike</td>\n",
+       "      <td>Brooks</td>\n",
+       "      <td>233.0</td>\n",
+       "      <td>NaN</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Islamabad</th>\n",
+       "      <td>Ali</td>\n",
+       "      <td>Shah</td>\n",
+       "      <td>223.0</td>\n",
+       "      <td>NaN</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>New York</th>\n",
+       "      <td>Luke</td>\n",
+       "      <td>Brown</td>\n",
+       "      <td>NaN</td>\n",
+       "      <td>NaN</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           first_name last_name  score  year\n",
+       "Tripoli     Noureddin    Sadawi    NaN   NaN\n",
+       "Birmingham      Josef     Baker    NaN   NaN\n",
+       "London           Mike    Brooks  233.0   NaN\n",
+       "Islamabad         Ali      Shah  223.0   NaN\n",
+       "New York         Luke     Brown    NaN   NaN"
+      ]
+     },
+     "execution_count": 8,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "m.dropna(how='all')"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 9,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style>\n",
+       "    .dataframe thead tr:only-child th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: left;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>first_name</th>\n",
+       "      <th>last_name</th>\n",
+       "      <th>score</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>Tripoli</th>\n",
+       "      <td>Noureddin</td>\n",
+       "      <td>Sadawi</td>\n",
+       "      <td>NaN</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Birmingham</th>\n",
+       "      <td>Josef</td>\n",
+       "      <td>Baker</td>\n",
+       "      <td>NaN</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>London</th>\n",
+       "      <td>Mike</td>\n",
+       "      <td>Brooks</td>\n",
+       "      <td>233.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Islamabad</th>\n",
+       "      <td>Ali</td>\n",
+       "      <td>Shah</td>\n",
+       "      <td>223.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>New York</th>\n",
+       "      <td>Luke</td>\n",
+       "      <td>Brown</td>\n",
+       "      <td>NaN</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           first_name last_name  score\n",
+       "Tripoli     Noureddin    Sadawi    NaN\n",
+       "Birmingham      Josef     Baker    NaN\n",
+       "London           Mike    Brooks  233.0\n",
+       "Islamabad         Ali      Shah  223.0\n",
+       "New York         Luke     Brown    NaN"
+      ]
+     },
+     "execution_count": 9,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "m.dropna(how='all',axis=1)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 10,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style>\n",
+       "    .dataframe thead tr:only-child th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: left;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>first_name</th>\n",
+       "      <th>last_name</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>Tripoli</th>\n",
+       "      <td>Noureddin</td>\n",
+       "      <td>Sadawi</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Birmingham</th>\n",
+       "      <td>Josef</td>\n",
+       "      <td>Baker</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>London</th>\n",
+       "      <td>Mike</td>\n",
+       "      <td>Brooks</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Islamabad</th>\n",
+       "      <td>Ali</td>\n",
+       "      <td>Shah</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>New York</th>\n",
+       "      <td>Luke</td>\n",
+       "      <td>Brown</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           first_name last_name\n",
+       "Tripoli     Noureddin    Sadawi\n",
+       "Birmingham      Josef     Baker\n",
+       "London           Mike    Brooks\n",
+       "Islamabad         Ali      Shah\n",
+       "New York         Luke     Brown"
+      ]
+     },
+     "execution_count": 10,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "m.dropna(how='all',axis=1,thresh=3)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style>\n",
+       "    .dataframe thead tr:only-child th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: left;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>first_name</th>\n",
+       "      <th>last_name</th>\n",
+       "      <th>score</th>\n",
+       "      <th>year</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>Tripoli</th>\n",
+       "      <td>Noureddin</td>\n",
+       "      <td>Sadawi</td>\n",
+       "      <td>1.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Birmingham</th>\n",
+       "      <td>Josef</td>\n",
+       "      <td>Baker</td>\n",
+       "      <td>1.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>London</th>\n",
+       "      <td>Mike</td>\n",
+       "      <td>Brooks</td>\n",
+       "      <td>233.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Islamabad</th>\n",
+       "      <td>Ali</td>\n",
+       "      <td>Shah</td>\n",
+       "      <td>223.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>New York</th>\n",
+       "      <td>Luke</td>\n",
+       "      <td>Brown</td>\n",
+       "      <td>1.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           first_name last_name  score  year\n",
+       "Tripoli     Noureddin    Sadawi    1.0   1.0\n",
+       "Birmingham      Josef     Baker    1.0   1.0\n",
+       "London           Mike    Brooks  233.0   1.0\n",
+       "Islamabad         Ali      Shah  223.0   1.0\n",
+       "New York         Luke     Brown    1.0   1.0"
+      ]
+     },
+     "execution_count": 12,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "m.fillna(1)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 13,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "m.fillna(1,inplace=True)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 14,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style>\n",
+       "    .dataframe thead tr:only-child th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: left;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>first_name</th>\n",
+       "      <th>last_name</th>\n",
+       "      <th>score</th>\n",
+       "      <th>year</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>Tripoli</th>\n",
+       "      <td>Noureddin</td>\n",
+       "      <td>Sadawi</td>\n",
+       "      <td>1.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Birmingham</th>\n",
+       "      <td>Josef</td>\n",
+       "      <td>Baker</td>\n",
+       "      <td>1.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>London</th>\n",
+       "      <td>Mike</td>\n",
+       "      <td>Brooks</td>\n",
+       "      <td>233.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Islamabad</th>\n",
+       "      <td>Ali</td>\n",
+       "      <td>Shah</td>\n",
+       "      <td>223.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>New York</th>\n",
+       "      <td>Luke</td>\n",
+       "      <td>Brown</td>\n",
+       "      <td>1.0</td>\n",
+       "      <td>1.0</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           first_name last_name  score  year\n",
+       "Tripoli     Noureddin    Sadawi    1.0   1.0\n",
+       "Birmingham      Josef     Baker    1.0   1.0\n",
+       "London           Mike    Brooks  233.0   1.0\n",
+       "Islamabad         Ali      Shah  223.0   1.0\n",
+       "New York         Luke     Brown    1.0   1.0"
+      ]
+     },
+     "execution_count": 14,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "m"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": []
+  }
+ ],
+ "metadata": {
+  "anaconda-cloud": {},
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.6.1"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 1
+}
diff --git a/notebooks/19-Sorting.ipynb b/notebooks/19-Sorting.ipynb
new file mode 100644
index 0000000..56ef0e5
--- /dev/null
+++ b/notebooks/19-Sorting.ipynb
@@ -0,0 +1,600 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": 7,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "import pandas as pd\n",
+    "import numpy as np"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 10,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style>\n",
+       "    .dataframe thead tr:only-child th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: left;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>col1</th>\n",
+       "      <th>col2</th>\n",
+       "      <th>col3</th>\n",
+       "      <th>col4</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>r1</th>\n",
+       "      <td>-0.536807</td>\n",
+       "      <td>-0.404254</td>\n",
+       "      <td>-0.159271</td>\n",
+       "      <td>-0.775606</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>r2</th>\n",
+       "      <td>-0.940191</td>\n",
+       "      <td>0.081161</td>\n",
+       "      <td>-0.269135</td>\n",
+       "      <td>0.081723</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>r3</th>\n",
+       "      <td>0.062271</td>\n",
+       "      <td>-0.340631</td>\n",
+       "      <td>-1.768370</td>\n",
+       "      <td>0.303790</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>r4</th>\n",
+       "      <td>0.471436</td>\n",
+       "      <td>-2.476170</td>\n",
+       "      <td>0.457263</td>\n",
+       "      <td>0.547299</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>r5</th>\n",
+       "      <td>0.239387</td>\n",
+       "      <td>-0.210741</td>\n",
+       "      <td>0.227696</td>\n",
+       "      <td>0.294547</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "        col1      col2      col3      col4\n",
+       "r1 -0.536807 -0.404254 -0.159271 -0.775606\n",
+       "r2 -0.940191  0.081161 -0.269135  0.081723\n",
+       "r3  0.062271 -0.340631 -1.768370  0.303790\n",
+       "r4  0.471436 -2.476170  0.457263  0.547299\n",
+       "r5  0.239387 -0.210741  0.227696  0.294547"
+      ]
+     },
+     "execution_count": 10,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "# here we create a simple dataframe with random values\n",
+    "raw_data = {\n",
+    "    'col1' : np.random.normal(size=5),\n",
+    "    'col2' : np.random.normal(size=5),\n",
+    "    'col3' : np.random.normal(size=5),\n",
+    "    'col4' : np.random.normal(size=5)\n",
+    "}\n",
+    "my_df = pd.DataFrame(raw_data, index = ['r1', 'r2', 'r3', 'r4', 'r5'])\n",
+    "my_df"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 12,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style>\n",
+       "    .dataframe thead tr:only-child th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: left;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>col1</th>\n",
+       "      <th>col2</th>\n",
+       "      <th>col3</th>\n",
+       "      <th>col4</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>r2</th>\n",
+       "      <td>-0.940191</td>\n",
+       "      <td>0.081161</td>\n",
+       "      <td>-0.269135</td>\n",
+       "      <td>0.081723</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>r1</th>\n",
+       "      <td>-0.536807</td>\n",
+       "      <td>-0.404254</td>\n",
+       "      <td>-0.159271</td>\n",
+       "      <td>-0.775606</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>r3</th>\n",
+       "      <td>0.062271</td>\n",
+       "      <td>-0.340631</td>\n",
+       "      <td>-1.768370</td>\n",
+       "      <td>0.303790</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>r5</th>\n",
+       "      <td>0.239387</td>\n",
+       "      <td>-0.210741</td>\n",
+       "      <td>0.227696</td>\n",
+       "      <td>0.294547</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>r4</th>\n",
+       "      <td>0.471436</td>\n",
+       "      <td>-2.476170</td>\n",
+       "      <td>0.457263</td>\n",
+       "      <td>0.547299</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "        col1      col2      col3      col4\n",
+       "r2 -0.940191  0.081161 -0.269135  0.081723\n",
+       "r1 -0.536807 -0.404254 -0.159271 -0.775606\n",
+       "r3  0.062271 -0.340631 -1.768370  0.303790\n",
+       "r5  0.239387 -0.210741  0.227696  0.294547\n",
+       "r4  0.471436 -2.476170  0.457263  0.547299"
+      ]
+     },
+     "execution_count": 12,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "my_df.sort_values(by='col1')"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 13,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style>\n",
+       "    .dataframe thead tr:only-child th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: left;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>col1</th>\n",
+       "      <th>col2</th>\n",
+       "      <th>col3</th>\n",
+       "      <th>col4</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>r2</th>\n",
+       "      <td>-0.940191</td>\n",
+       "      <td>0.081161</td>\n",
+       "      <td>-0.269135</td>\n",
+       "      <td>0.081723</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>r1</th>\n",
+       "      <td>-0.536807</td>\n",
+       "      <td>-0.404254</td>\n",
+       "      <td>-0.159271</td>\n",
+       "      <td>-0.775606</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>r3</th>\n",
+       "      <td>0.062271</td>\n",
+       "      <td>-0.340631</td>\n",
+       "      <td>-1.768370</td>\n",
+       "      <td>0.303790</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>r5</th>\n",
+       "      <td>0.239387</td>\n",
+       "      <td>-0.210741</td>\n",
+       "      <td>0.227696</td>\n",
+       "      <td>0.294547</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>r4</th>\n",
+       "      <td>0.471436</td>\n",
+       "      <td>-2.476170</td>\n",
+       "      <td>0.457263</td>\n",
+       "      <td>0.547299</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "        col1      col2      col3      col4\n",
+       "r2 -0.940191  0.081161 -0.269135  0.081723\n",
+       "r1 -0.536807 -0.404254 -0.159271 -0.775606\n",
+       "r3  0.062271 -0.340631 -1.768370  0.303790\n",
+       "r5  0.239387 -0.210741  0.227696  0.294547\n",
+       "r4  0.471436 -2.476170  0.457263  0.547299"
+      ]
+     },
+     "execution_count": 13,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "my_df.sort_values(by=['col1','col4'])"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": []
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 14,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style>\n",
+       "    .dataframe thead tr:only-child th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: left;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>first_name</th>\n",
+       "      <th>last_name</th>\n",
+       "      <th>score</th>\n",
+       "      <th>year</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>Tripoli</th>\n",
+       "      <td>Noureddin</td>\n",
+       "      <td>Sadawi</td>\n",
+       "      <td>422</td>\n",
+       "      <td>2015</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Birmingham</th>\n",
+       "      <td>Josef</td>\n",
+       "      <td>Baker</td>\n",
+       "      <td>322</td>\n",
+       "      <td>2009</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>London</th>\n",
+       "      <td>Mike</td>\n",
+       "      <td>Brooks</td>\n",
+       "      <td>233</td>\n",
+       "      <td>2013</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Islamabad</th>\n",
+       "      <td>Ali</td>\n",
+       "      <td>Shah</td>\n",
+       "      <td>223</td>\n",
+       "      <td>2016</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>New York</th>\n",
+       "      <td>Luke</td>\n",
+       "      <td>Brown</td>\n",
+       "      <td>401</td>\n",
+       "      <td>2014</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           first_name last_name  score  year\n",
+       "Tripoli     Noureddin    Sadawi    422  2015\n",
+       "Birmingham      Josef     Baker    322  2009\n",
+       "London           Mike    Brooks    233  2013\n",
+       "Islamabad         Ali      Shah    223  2016\n",
+       "New York         Luke     Brown    401  2014"
+      ]
+     },
+     "execution_count": 14,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "raw_data = {'first_name': ['Noureddin', 'Josef', 'Mike', 'Ali', 'Luke'],\n",
+    "        'last_name': ['Sadawi', 'Baker', 'Brooks', 'Shah', 'Brown'],\n",
+    "        'year': [2015,2009,2013,2016,2014],\n",
+    "        'score': [422,322,233,223,401]}\n",
+    "df = pd.DataFrame(raw_data, index = ['Tripoli', 'Birmingham', 'London', 'Islamabad', 'New York'])\n",
+    "df"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 19,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style>\n",
+       "    .dataframe thead tr:only-child th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: left;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>first_name</th>\n",
+       "      <th>last_name</th>\n",
+       "      <th>score</th>\n",
+       "      <th>year</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>Islamabad</th>\n",
+       "      <td>Ali</td>\n",
+       "      <td>Shah</td>\n",
+       "      <td>223</td>\n",
+       "      <td>2016</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Tripoli</th>\n",
+       "      <td>Noureddin</td>\n",
+       "      <td>Sadawi</td>\n",
+       "      <td>422</td>\n",
+       "      <td>2015</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>New York</th>\n",
+       "      <td>Luke</td>\n",
+       "      <td>Brown</td>\n",
+       "      <td>401</td>\n",
+       "      <td>2014</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>London</th>\n",
+       "      <td>Mike</td>\n",
+       "      <td>Brooks</td>\n",
+       "      <td>233</td>\n",
+       "      <td>2013</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Birmingham</th>\n",
+       "      <td>Josef</td>\n",
+       "      <td>Baker</td>\n",
+       "      <td>322</td>\n",
+       "      <td>2009</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           first_name last_name  score  year\n",
+       "Islamabad         Ali      Shah    223  2016\n",
+       "Tripoli     Noureddin    Sadawi    422  2015\n",
+       "New York         Luke     Brown    401  2014\n",
+       "London           Mike    Brooks    233  2013\n",
+       "Birmingham      Josef     Baker    322  2009"
+      ]
+     },
+     "execution_count": 19,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "df.sort_values(by='last_name',ascending=False)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 20,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<div>\n",
+       "<style>\n",
+       "    .dataframe thead tr:only-child th {\n",
+       "        text-align: right;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe thead th {\n",
+       "        text-align: left;\n",
+       "    }\n",
+       "\n",
+       "    .dataframe tbody tr th {\n",
+       "        vertical-align: top;\n",
+       "    }\n",
+       "</style>\n",
+       "<table border=\"1\" class=\"dataframe\">\n",
+       "  <thead>\n",
+       "    <tr style=\"text-align: right;\">\n",
+       "      <th></th>\n",
+       "      <th>first_name</th>\n",
+       "      <th>last_name</th>\n",
+       "      <th>score</th>\n",
+       "      <th>year</th>\n",
+       "    </tr>\n",
+       "  </thead>\n",
+       "  <tbody>\n",
+       "    <tr>\n",
+       "      <th>Birmingham</th>\n",
+       "      <td>Josef</td>\n",
+       "      <td>Baker</td>\n",
+       "      <td>322</td>\n",
+       "      <td>2009</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>London</th>\n",
+       "      <td>Mike</td>\n",
+       "      <td>Brooks</td>\n",
+       "      <td>233</td>\n",
+       "      <td>2013</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>New York</th>\n",
+       "      <td>Luke</td>\n",
+       "      <td>Brown</td>\n",
+       "      <td>401</td>\n",
+       "      <td>2014</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Tripoli</th>\n",
+       "      <td>Noureddin</td>\n",
+       "      <td>Sadawi</td>\n",
+       "      <td>422</td>\n",
+       "      <td>2015</td>\n",
+       "    </tr>\n",
+       "    <tr>\n",
+       "      <th>Islamabad</th>\n",
+       "      <td>Ali</td>\n",
+       "      <td>Shah</td>\n",
+       "      <td>223</td>\n",
+       "      <td>2016</td>\n",
+       "    </tr>\n",
+       "  </tbody>\n",
+       "</table>\n",
+       "</div>"
+      ],
+      "text/plain": [
+       "           first_name last_name  score  year\n",
+       "Birmingham      Josef     Baker    322  2009\n",
+       "London           Mike    Brooks    233  2013\n",
+       "New York         Luke     Brown    401  2014\n",
+       "Tripoli     Noureddin    Sadawi    422  2015\n",
+       "Islamabad         Ali      Shah    223  2016"
+      ]
+     },
+     "execution_count": 20,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "df.sort_values(by=['last_name','score'])"
+   ]
+  }
+ ],
+ "metadata": {
+  "anaconda-cloud": {},
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.6.1"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 1
+}