4. Lambdas & Functions.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Lambdas"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Python lambdas are little, anonymous functions, subject to a more restrictive but more concise syntax than regular Python functions."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "4"
      ]
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "def square(i):\n",
    "    return i*i\n",
    "\n",
    "square(2)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
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       "4"
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     "execution_count": 2,
     "metadata": {},
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   ],
   "source": [
    "func = lambda x: x*x\n",
    "func(2)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Immediately Invoked Function Expression(IFFE)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "This style is very much popular in languages like JavaScript where w function is called as soon as it is defined"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "3"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "(lambda x: x + 1)(2)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Functions & it's arguments"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Positional arguments"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "2\n"
     ]
    }
   ],
   "source": [
    "def custom_function(param1, param2):\n",
    "    print(param1)\n",
    "    print(param2)\n",
    "\n",
    "\n",
    "custom_function(1, 2)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Keyword Arguments"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "2\n",
      "2\n",
      "1\n"
     ]
    }
   ],
   "source": [
    "def custom_function(param1, param2):\n",
    "    print(param1)\n",
    "    print(param2)\n",
    "\n",
    "\n",
    "custom_function(param1=1, param2=2)\n",
    "custom_function(param2=1, param1=2)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Default arguments"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "2\n",
      "1\n",
      "2\n",
      "1\n",
      "2\n"
     ]
    }
   ],
   "source": [
    "def custom_function(param1, param2=2):\n",
    "    print(param1)\n",
    "    print(param2)\n",
    "\n",
    "\n",
    "custom_function(1, 2)\n",
    "custom_function(1)\n",
    "custom_function(1, param2=2)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Arbitrary Arguments"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "(1, 2)\n",
      "(1, 2, 3)\n"
     ]
    }
   ],
   "source": [
    "def custom_function(*args):\n",
    "    print(args)\n",
    "\n",
    "\n",
    "custom_function(1, 2)\n",
    "custom_function(1, 2, 3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Arbitrary Keyword Arguments"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'a': 1, 'b': 2}\n",
      "{'a': 1, 'b': 2, 'c': 3}\n"
     ]
    }
   ],
   "source": [
    "def custom_function(**kwargs):\n",
    "    print(kwargs)\n",
    "\n",
    "\n",
    "custom_function(a=1, b=2)\n",
    "custom_function(a=1, b=2, c=3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Positional-only parameters"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "1\n",
      "2\n",
      "3\n",
      "4\n"
     ]
    },
    {
     "ename": "TypeError",
     "evalue": "custom_function() got some positional-only arguments passed as keyword arguments: 'param1, param2'",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-9-d26406439044>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[1;32m      7\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m      8\u001b[0m \u001b[0mcustom_function\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;36m2\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mkwparam1\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m3\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mkwparam2\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m4\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 9\u001b[0;31m \u001b[0mcustom_function\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mparam2\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mparam1\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m2\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mkwparam1\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m3\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mkwparam2\u001b[0m\u001b[0;34m=\u001b[0m\u001b[0;36m4\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: custom_function() got some positional-only arguments passed as keyword arguments: 'param1, param2'"
     ]
    }
   ],
   "source": [
    "def custom_function(param1, param2, /, kwparam1, kwparam2):\n",
    "    print(param1)\n",
    "    print(param2)\n",
    "    print(kwparam1)\n",
    "    print(kwparam2)\n",
    "\n",
    "\n",
    "custom_function(1, 2, kwparam1=3, kwparam2=4)\n",
    "custom_function(param2=1, param1=2, kwparam1=3, kwparam2=4)"
   ]
  }
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