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   "source": [
    "# How do you explore what makes up an object?\n",
    "\n",
    "The `dir` built-in function in Python allows one to *explore the contents* of an object.\n",
    "\n",
    "<img src=\"../images/dir_doc.png\" style=\"padding: 0 1em; height: 6em;\">\n",
    "\n",
    "That is, the `dir` function returns a `list` of an object's *attributes*, which can be either *data* (i.e., variables) or *functions*."
   ]
  },
  {
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   "metadata": {
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   "source": [
    "## Everything in Python is an object!\n",
    "\n",
    "Don't believe me?  Try out the `dir` function on anything you can think of..."
   ]
  },
  {
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   "id": "037b6557-8519-493d-ba11-8f653b902cda",
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   "source": [
    "### Example: Strings have attributes"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "afa88f7d-bd5e-4242-93f6-acd2bfd9de17",
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
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    "tags": []
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   "outputs": [],
   "source": [
    "dir('string')"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "560c1817-77d6-4bf4-b19d-3f7e66dbf8eb",
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   "source": [
    "<div class=\"alert alert-info\">\n",
    "    <b>Note:</b>\n",
    "    <p>Some attributes have names that start with __ (double-underscore).  In Python, variables or functions that start with a double-underscore are treated as \"private.\"  In general, variables or functions that start with a double-underscore <em>and end with a double-underscore</em> typically have special meaning.  We'll get to that later.</p>\n",
    "</div>"
   ]
  },
  {
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   "id": "aa59784d-678d-42a0-9163-471ba3441438",
   "metadata": {
    "slideshow": {
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    "tags": []
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   "source": [
    "### Example: Numbers have attributes"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "44fc2b6f-b851-4440-8233-f173a0439e0f",
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    },
    "tags": []
   },
   "outputs": [],
   "source": [
    "dir(1)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "630529a1-9d08-48d1-bf80-b1e865ee3a75",
   "metadata": {
    "slideshow": {
     "slide_type": "subslide"
    },
    "tags": []
   },
   "source": [
    "### Exercise: Try it out with other data types..."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "9e4f7248-e29d-4e89-ada2-c11d724ead44",
   "metadata": {
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     "slide_type": "fragment"
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    "tags": []
   },
   "outputs": [],
   "source": [
    "# What attributes does a list have?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "447185b6-f454-4d36-9553-83958921b94b",
   "metadata": {},
   "outputs": [],
   "source": [
    "# What attributes does a dict have?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "e221812d-85d3-4567-9a97-b1b67bfb830b",
   "metadata": {},
   "outputs": [],
   "source": [
    "# What attributes does a function have?"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "0f9e2d8b-eb8e-4677-9309-5dbecddf1656",
   "metadata": {
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    "tags": []
   },
   "source": [
    "<div class=\"alert alert-warning\">\n",
    "    <b>Question:</b>\n",
    "    <p>Do you recognize any of the attributes listed above?</p>\n",
    "</div>"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a46483b3-fc71-457e-88c6-20800710ccb2",
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   "source": [
    "## Tab Completion in Jupyter Notebooks!\n",
    "\n",
    "Jupyter Notebooks have the wonderful ability to *show* you an object's attributes just by adding a \"dot\" and then hitting tab.  Jupyter's built-in **tab completion** capability will then pop up a window to show you the attributes of the object!"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "429809e6-5841-4c54-9b06-7be301aa2e5b",
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   "source": [
    "### Example: Tab completion to show an integer's attributes"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "bc8c9e18-cec3-4a6a-863f-d18ffbf98e20",
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   "source": [
    "i = 2"
   ]
  },
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   "cell_type": "code",
   "execution_count": null,
   "id": "8c6d10e5-ffbf-4f3c-ba9f-7673808a4e99",
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   "source": [
    "i."
   ]
  },
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   "cell_type": "markdown",
   "id": "dbdc57f8-9565-4006-aa1d-ef9e2fcad0b3",
   "metadata": {
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   "source": [
    "<div class=\"alert alert-info\">\n",
    "    <b>Note:</b>\n",
    "    <p>Jupyter's visual \"pop-up\" shows an object's <em>public</em> attributes only.  If you are using JupyterLab, you will see that each attribute is labeled as either an <em>instance</em> (i.e., <em>data</em>) or a <em>function</em>.  If you are using classic Jupyter Notebooks, then you will just see a list of the attributes (without additional labeling).</p>\n",
    "</div>"
   ]
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  {
   "cell_type": "markdown",
   "id": "872a9897-599e-4476-a5f1-f73cad882434",
   "metadata": {
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    },
    "tags": []
   },
   "source": [
    "<div class=\"alert alert-info\">\n",
    "    <b>Note:</b>\n",
    "    <p>Jupyter can't give you a pop-up window unless the variable you are using to tab-complete is already defined and created!</p>\n",
    "</div>"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "ce84dbd3-9c9c-4a85-90da-ff60fa52d183",
   "metadata": {},
   "source": [
    "|    |    |    |\n",
    "| :- | -- | -: |\n",
    "| [[Home]](../index.ipynb) | <img width=\"100%\" height=\"1\" src=\"../images/empty.png\"/> | [&laquo;&nbsp;Previous](01.ipynb)&nbsp;\\|&nbsp;[Next&nbsp;&raquo;](03.ipynb) |"
   ]
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