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   "source": [
    "### Special characters\n",
    "\n",
    "When we use strings, you will notice that we often want to use some \"_special characters_\". These special characters consist of the backslash character (`\\`) followed by another character.\n",
    "\n",
    "**Tab character** `\\t`: For example, if we want to create an output of multiple columns, with each columns being separated with a tab from each other, we can use the tab character, which is represented as `\\t`. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Example: List the first name, last name, and email of a person, in columns\n",
    "# Separate the columns using a tab character\n",
    "str_4a =\"First Name\\tLast Name\\tEmail\"\n",
    "str_4b =\"Panagiotis\\tIpeirotis\\tpanos@nyu.edu\"\n",
    "str_4c =\"Kristaps\\tPorzingis\\tkporzee@nba.com\"\n",
    "print(str_4a)\n",
    "print(str_4b)\n",
    "print(str_4c)\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**New line character** `\\n`: This is a special character that we use to represent a new line."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Notice that we end the strings below with the \\n character, \n",
    "# which is the \"new line\" special character\n",
    "str_5 = \"Hello World!\\nHello World Twice!\"\n",
    "print(str_5)\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Backslash character** `\\\\`: In general, backslash (`\\`) is used to introduce special characters. If we want to type the backslash character itself, we do it by typing backslash twice in a row: `\\\\`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(\"I want to print backslash: \\\\\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Quotes**: "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "str_4 = 'This is a string within single quotes that can contain \"double quotes\" as part of the string'\n",
    "print(str_4)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "str_5 = 'If we want to have \\'single quotes\\' in single quoted string we should escape them'\n",
    "print(str_5)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "str_6 = \"Similarly, if we want to have \\\"double quotes\\\" in double quoted string we should escape them\\n\"\n",
    "print(str_6)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Splitting Strings: `split` and `join`\n",
    "\n",
    "Since we talked about special characters, let’s talk now about splitting strings, using the `split()` function.\n",
    "\n",
    "\n",
    "+ `longstring.split(separator)`: split the first string (longstring) at every occurrence of the second string (separator) Outputs a list (see below).\n",
    "+ `connector.join(list)`:  join is the \"reverse\" of split, and joins all  the elements of the list, using the `connector` string in front."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(\"practical data science\".split(\" \"))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(\"billgates@microsoft.com\".split(\"@\"))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Or let's take the example from above:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "str_a =\"First Name\\tLast Name\\tEmail\"\n",
    "str_b =\"Panagiotis\\tIpeirotis\\tpanos@nyu.edu\"\n",
    "str_c =\"Kristaps\\tPorzingis\\tkporzee@nba.com\"\n",
    "print(str_a.split('\\t'))\n",
    "print(str_b.split('\\t'))\n",
    "print(str_c.split('\\t'))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Notice that when we split a string and the delimeter character\n",
    "does not appear, then we get back the string itself, but converted\n",
    "into a list with a single element. (We will talk about lists in a \n",
    " couple of weeks)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "print(\"hello\".split(\" \"))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "  Join is the \"reverse\" of split, and joins all\n",
    " the elements of the list, using the \"string\" in front.\n",
    " The command below joins the elements of the `line` variable using the \n",
    " characters `###` as the connecting element."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "line = ['Panagiotis', 'Ipeirotis', 'panos@nyu.edu']\n",
    "\"###\".join(line)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Exercise\n",
    "\n",
    "Consider the string `billgates@microsoft.com`. Write code that finds the username of the email address and the domain of the email address, using the `split()` command."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "email = \"billgates@microsoft.com\"\n",
    "result = email.split(\"@\")\n",
    "print(result)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# We can also access the individual elements of a list using indexing\n",
    "print(\"Username:\", result[0])\n",
    "print(\"Domain:\", result[1])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "email = \"billgates@microsoft.com\"\n",
    "result = email.split(\"@\")\n",
    "print(result)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# And if we want to access the individual elements of a list we can use the indexing notation, as in the case of strings:\n",
    "print(\"Username:\", result[0])\n",
    "print(\"Domain:\", result[1])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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