07-python_modules.ipynb

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    "## 7. Python Modules\n",
    "**What is a Module?**\n",
    "Consider a module to be the same as a code library.\n",
    "A file containing a set of functions you want to include in your application.\n",
    "### Import - Getting Code from Modules\n",
    "The module called `math`, which provides access to many mathematical functions."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import math"
   ]
  },
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   "source": [
    "# You may use the `sqrt` function within the `math` module:\n",
    "math.sqrt(9)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "builtin_function_or_method"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "type(math.sqrt)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
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       "3.141592653589793"
      ]
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     "execution_count": 4,
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     "output_type": "execute_result"
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   ],
   "source": [
    "math.pi"
   ]
  },
  {
   "cell_type": "code",
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       "float"
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   "source": [
    "type(math.pi)"
   ]
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   "source": [
    "# using the `pow` function from the `math` module:\n",
    "math.pow(10,2)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
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     "text": [
      "Help on built-in function pow in module math:\n",
      "\n",
      "pow(x, y, /)\n",
      "    Return x**y (x to the power of y).\n",
      "\n"
     ]
    }
   ],
   "source": [
    "help(math.pow)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
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     "execution_count": 8,
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   "source": [
    "# using the `prod` to calculate the product of of all elements in a number list \n",
    "\n",
    "no_list = [1, 2, 3, 4, 5] \n",
    "  \n",
    "math.prod(no_list) "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "100"
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     "execution_count": 10,
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   ],
   "source": [
    "# Use the 'tab' key to view the list of attributes and methods of the module\n",
    "math.lcm(10,100)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Use help to get the detail of the function in math module\n",
    "help(math.pow)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# For example you may access e constant (Euler's number)\n",
    "math.e"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# pi from math module\n",
    "math.pi"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#import the statistic library\n",
    "\n",
    "import statistics"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Calculate the mean using mean method in statistics\n",
    "statistics.mean(no_list)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "help(statistics)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "statistics.mean([1,2,3])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "statistics.median([1, 3, 5])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<font color=\"blue\">Exercise</font>: Define a function called `cal_sphere_volume` that accepts one argument called `radius`. The function should return the volume of the sphere.\n",
    "\n",
    "The function should use the `pi` value from math module and the function `math.pow` above to implement the formula $\\frac{4}{3}\\pi r^3$:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# YOUR CODE HERE\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "cal_sphere_volume(2)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Another built in Module: The `random` Module\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import random"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# The randint() method returns an integer number selected element from the specified range.\n",
    "#Return a number between 0 and 20 (both included):\n",
    "random.randint(0,20)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# The following code demonstrate that if you use the same seed value twice, you will get the same random number twice.\n",
    "# Re-run the codes and you will get the same value\n",
    "\n",
    "random.seed(100)\n",
    "random.randint(0,1000)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "#The shuffle() method takes a sequence (list, string, or tuple) and reorganize the order of the items.\n",
    "number_list = [1,2,3,4,5,6,7]\n",
    "random.shuffle(number_list)\n",
    "number_list"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "help(random)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Return a list that contains any k of the items from a list:\n",
    "\n",
    "number_list = [1,2,3,4,5,6,7,8,9,10]\n",
    "#random.seed(8)\n",
    "print(random.sample(k=4,population=number_list))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "random.sample"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### differrent way of import\n",
    "If we just want to use the `randint` function from the `random` module, we can import it a different way:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "from random import randint"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Then we are allowed to call the randint function without typing the module name.\n",
    "randint(0,1000)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# The earlier way of calling the method without using 'from random import randint'\n",
    "random.randint(0,1000)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# similar way of importing mean from statistics module\n",
    "from statistics import mean"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "mean([1,2,5,6,8])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import statistics"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "statistics.mean([1,2,5,6,8])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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