5.1 Creating and Calling Functions.ipynb

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   "source": [
    "<center><em>Copyright! This material is protected, please do not copy or distribute.    by:Taher Assaf</em></center>"
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   "source": [
    "***\n",
    "<h1 align=\"center\">Udemy course : Python Bootcamp for Data Science 2021 Numpy Pandas & Seaborn</h1> \n",
    "\n",
    "***"
   ]
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   "source": [
    "## 5.1 Creating and Calling Functions"
   ]
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   "source": [
    "We can create a simple function that adds to number like this:"
   ]
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   "source": [
    "def sum_function(a, b):\n",
    "    sum = a + b\n",
    "    return sum"
   ]
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   "source": [
    "We can call a function like this:"
   ]
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    "sum_function(4,5)"
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   "source": [
    "We can add an optional argument, if we specify its value, for example (c=1) in this example:"
   ]
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   "source": [
    "def sum_function(a, b, c= 1):\n",
    "    sum1 = a + b\n",
    "    weighted_sum = sum1/c \n",
    "    return weighted_sum"
   ]
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   "source": [
    "We can call the function without the optional argument"
   ]
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   "source": [
    "sum_function(4,5)"
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   "source": [
    "Also we can call the function with the optional argument, the new value is used for the optional argument."
   ]
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   "execution_count": 5,
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   "outputs": [
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     "data": {
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       "4.5"
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     "execution_count": 5,
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   "source": [
    "sum_function(4,5,2)"
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   "source": [
    "For calrity, we can use the name of the arguments as well:"
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       "4.5"
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     "execution_count": 6,
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   "source": [
    "sum_function(a = 4, b = 5, c= 2)"
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   "source": [
    "The variable insdie the function cannot be accesses from ouside, because it is a local variable. if we try to access a local variable we get an **error**:"
   ]
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   "execution_count": 7,
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   "outputs": [
    {
     "ename": "NameError",
     "evalue": "name 'sum1' is not defined",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mNameError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-7-24dd84727fca>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m\u001b[0m\n\u001b[1;32m----> 1\u001b[1;33m \u001b[0msum1\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[1;31mNameError\u001b[0m: name 'sum1' is not defined"
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    "sum1"
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    "We can declare a local variable to be a global variable like this:"
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    "sum1 = None"
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   "source": [
    "def sum_function(a, b, c= 1):\n",
    "    global sum1\n",
    "    sum1 = a + b\n",
    "    weighted_sum = sum1/c \n",
    "    return weighted_sum"
   ]
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   "source": [
    "The function can be called normally:"
   ]
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   "execution_count": 10,
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    "sum_function(4,5)"
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   "source": [
    "And we can now also access the variable inside the function without any problem:"
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    "sum1"
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   "source": [
    "***\n",
    "\n",
    "<h1 align=\"center\">Thank You</h1> \n",
    "\n",
    "***"
   ]
  }
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