15 - Functions Basics - Part 2.ipynb

{"nbformat":4,"nbformat_minor":0,"metadata":{"colab":{"name":"function_types.ipynb","version":"0.3.2","provenance":[]},"kernelspec":{"display_name":"Python 3","language":"python","name":"python3"}},"cells":[{"metadata":{"id":"RqxIugMnDy18","colab_type":"text"},"cell_type":"markdown","source":["# Types Of Functions"]},{"metadata":{"id":"MeGY4QcFDy2B","colab_type":"text"},"cell_type":"markdown","source":["1. Built-in Functions\n","\n","2. User-defined Functions"]},{"metadata":{"id":"ilt0Wb4sDy2E","colab_type":"text"},"cell_type":"markdown","source":["# Built-in Functions"]},{"metadata":{"id":"ubtJWhwrDy2F","colab_type":"text"},"cell_type":"markdown","source":["# 1. abs()"]},{"metadata":{"id":"cs7rqfNGDy2H","colab_type":"code","colab":{},"outputId":"9b7c7119-c7ac-4687-c6d2-2c1f4beedb6b"},"cell_type":"code","source":["# find the absolute value\n","\n","num = -100\n","\n","print(abs(num))\n"],"execution_count":0,"outputs":[{"output_type":"stream","text":["100\n"],"name":"stdout"}]},{"metadata":{"id":"Ao4an2SJDy2V","colab_type":"text"},"cell_type":"markdown","source":["# 2. all()"]},{"metadata":{"id":"s7KNa-qjDy2X","colab_type":"text"},"cell_type":"markdown","source":["#return value of all() function\n","\n","True: if all elements in an iterable are true\n","\n","False: if any element in an iterable is false"]},{"metadata":{"id":"BUYpaNxDDy2Z","colab_type":"code","colab":{},"outputId":"4155af24-b996-48bc-f94f-96455fc6c295"},"cell_type":"code","source":["lst = [1, 2, 3, 4]\n","print(all(lst)) \n"],"execution_count":0,"outputs":[{"output_type":"stream","text":["True\n"],"name":"stdout"}]},{"metadata":{"id":"PMh2XjhmDy2g","colab_type":"code","colab":{},"outputId":"3fcc42c4-b996-4002-c2bc-4379c765ae57"},"cell_type":"code","source":["lst = (0, 2, 3, 4)    # 0 present in list \n","print(all(lst))\n"],"execution_count":0,"outputs":[{"output_type":"stream","text":["False\n"],"name":"stdout"}]},{"metadata":{"id":"A1612gmHDy2n","colab_type":"code","colab":{},"outputId":"5ab9f21d-d79d-43c0-e021-018ba8228f32"},"cell_type":"code","source":["lst = []              #empty list always true\n","print(all(lst))\n"],"execution_count":0,"outputs":[{"output_type":"stream","text":["True\n"],"name":"stdout"}]},{"metadata":{"id":"EFwmHv_kDy2v","colab_type":"code","colab":{},"outputId":"d466ad84-2d91-4ceb-bf13-c808f8dfcd2d"},"cell_type":"code","source":["lst = [False, 1, 2]   #False present in a list so all(lst) is False\n","print(all(lst))\n"],"execution_count":0,"outputs":[{"output_type":"stream","text":["False\n"],"name":"stdout"}]},{"metadata":{"id":"Vpyu5OLGDy2z","colab_type":"text"},"cell_type":"markdown","source":["# dir()"]},{"metadata":{"id":"hKSi83LiDy20","colab_type":"text"},"cell_type":"markdown","source":["The dir() tries to return a list of valid attributes of the object.\n","\n","If the object has __dir__() method, the method will be called and must return the list of attributes.\n","\n","If the object doesn't have __dir()__ method, this method tries to find information from the __dict__ attribute (if defined), and from type object. In this case, the list returned from dir() may not be complete.\n"]},{"metadata":{"id":"x3-LaQj8Dy22","colab_type":"code","colab":{},"outputId":"fadf0dbd-4c71-41bd-b759-968236a0a696"},"cell_type":"code","source":["numbers = [1, 2, 3]\n","\n","print(dir(numbers))\n"],"execution_count":0,"outputs":[{"output_type":"stream","text":["['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'append', 'clear', 'copy', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']\n"],"name":"stdout"}]},{"metadata":{"id":"qAkLDrzDDy27","colab_type":"text"},"cell_type":"markdown","source":["# divmod()"]},{"metadata":{"id":"Z7PAJz9RDy28","colab_type":"text"},"cell_type":"markdown","source":["The divmod() method takes two numbers and returns a pair of numbers (a tuple) consisting of their quotient and remainder."]},{"metadata":{"id":"6V3UUIj-Dy29","colab_type":"code","colab":{},"outputId":"51645660-aa7a-4d6d-b162-effe6e5db99b"},"cell_type":"code","source":["print(divmod(9, 2)) #print quotient and remainder as a tuple\n","\n","#try with other number\n"],"execution_count":0,"outputs":[{"output_type":"stream","text":["(4, 1)\n"],"name":"stdout"}]},{"metadata":{"id":"3XcOj4ahDy3A","colab_type":"text"},"cell_type":"markdown","source":["# enumerate()"]},{"metadata":{"id":"sPGIxThfDy3C","colab_type":"text"},"cell_type":"markdown","source":["The enumerate() method adds counter to an iterable and returns it "]},{"metadata":{"id":"PsPTJ9w3Dy3C","colab_type":"text"},"cell_type":"markdown","source":["syntax: enumerate(iterable, start=0)"]},{"metadata":{"id":"LzYe1WyTDy3E","colab_type":"code","colab":{},"outputId":"d97df55a-531b-4f3f-c4b9-09053c31f337"},"cell_type":"code","source":["numbers = [10, 20, 30, 40]\n","\n","for index, num in enumerate(numbers,10):\n","    print(\"index {0} has value {1}\".format(index, num))\n","    "],"execution_count":0,"outputs":[{"output_type":"stream","text":["index 10 has value 10\n","index 11 has value 20\n","index 12 has value 30\n","index 13 has value 40\n"],"name":"stdout"}]},{"metadata":{"id":"Qv7BOrOjDy3I","colab_type":"text"},"cell_type":"markdown","source":["# filter()"]},{"metadata":{"id":"K8_DVZ2uDy3J","colab_type":"text"},"cell_type":"markdown","source":["The filter() method constructs an iterator from elements of an iterable for which a function returns true."]},{"metadata":{"id":"Xsq_-ITBDy3K","colab_type":"text"},"cell_type":"markdown","source":["syntax: filter(function, iterable)"]},{"metadata":{"id":"-Nclc6WjDy3L","colab_type":"code","colab":{}},"cell_type":"code","source":["def find_positive_number(num):\n","    \"\"\"\n","    This function returns the positive number if num is positive\n","    \"\"\"\n","    if num > 0:\n","        return num\n","    "],"execution_count":0,"outputs":[]},{"metadata":{"id":"ef_Se6snDy3Q","colab_type":"code","colab":{},"outputId":"8fb2019e-3862-47e5-ff75-8be51c7ca567"},"cell_type":"code","source":["number_list = range(-10, 10) #create a list with numbers from -10 to 10\n","print(list(number_list))\n","\n","positive_num_lst = list(filter(find_positive_number, number_list))\n","\n","print(positive_num_lst)\n"],"execution_count":0,"outputs":[{"output_type":"stream","text":["[-10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]\n","[1, 2, 3, 4, 5, 6, 7, 8, 9]\n"],"name":"stdout"}]},{"metadata":{"id":"i1jHDq_5Dy3Z","colab_type":"text"},"cell_type":"markdown","source":["# isinstance()"]},{"metadata":{"id":"eSZpUEYnDy3b","colab_type":"text"},"cell_type":"markdown","source":["The isinstance() function checks if the object (first argument) is an instance or subclass of classinfo class (second argument)."]},{"metadata":{"id":"JYB_W3vfDy3e","colab_type":"text"},"cell_type":"markdown","source":["syntax: isinstance(object, classinfo)"]},{"metadata":{"id":"JMAYKKXZDy3f","colab_type":"code","colab":{},"outputId":"42dc66ee-8ee9-434e-c523-c35ed9653b09"},"cell_type":"code","source":["lst = [1, 2, 3, 4]\n","print(isinstance(lst, list))\n","\n","#try with other datatypes tuple, set\n","t = (1,2,3,4)\n","print(isinstance(t, list))"],"execution_count":0,"outputs":[{"output_type":"stream","text":["True\n","False\n"],"name":"stdout"}]},{"metadata":{"id":"0SzHgv87Dy3k","colab_type":"text"},"cell_type":"markdown","source":["# map()"]},{"metadata":{"id":"eAqVlxbtDy3m","colab_type":"text"},"cell_type":"markdown","source":["Map applies a function to all the items in an input_list."]},{"metadata":{"id":"oHivUTbRDy3m","colab_type":"text"},"cell_type":"markdown","source":["syntax: map(function_to_apply, list_of_inputs)"]},{"metadata":{"id":"YrzZKvFMDy3n","colab_type":"code","colab":{},"outputId":"bdcc45b2-5a0e-43e7-be55-cc3749c03498"},"cell_type":"code","source":["numbers = [1, 2, 3, 4]\n","\n","#normal method of computing num^2 for each element in the list.\n","squared = []\n","for num in numbers:\n","    squared.append(num ** 2)\n","\n","print(squared)\n"],"execution_count":0,"outputs":[{"output_type":"stream","text":["[1, 4, 9, 16]\n"],"name":"stdout"}]},{"metadata":{"id":"SWKg9_nYDy3r","colab_type":"code","colab":{},"outputId":"50395f75-d023-4dca-ca24-431a527e1e97"},"cell_type":"code","source":["numbers = [1, 2, 3, 4]\n","\n","def powerOfTwo(num):\n","    return num ** 2\n","\n","#using map() function\n","squared = list(map(powerOfTwo, numbers))\n","print(squared)\n"],"execution_count":0,"outputs":[{"output_type":"stream","text":["[1, 4, 9, 16]\n"],"name":"stdout"}]},{"metadata":{"id":"-ZZiI7m5Dy3t","colab_type":"text"},"cell_type":"markdown","source":["# reduce()"]},{"metadata":{"id":"u_pxdMIcDy3v","colab_type":"text"},"cell_type":"markdown","source":["reduce() function is for performing some computation on a list and returning the result. \n","\n","It applies a rolling computation to sequential pairs of values in a list. "]},{"metadata":{"id":"jqx-xAf7Dy3w","colab_type":"code","colab":{},"outputId":"182c1097-2ed9-4197-bdaf-8b7866401a4d"},"cell_type":"code","source":["#product of elemnts in a list\n","product = 1\n","lst = [1, 2, 3, 4]\n","\n","# traditional program without reduce()\n","for num in lst:\n","    product *= num\n","print(product)\n"],"execution_count":0,"outputs":[{"output_type":"stream","text":["24\n"],"name":"stdout"}]},{"metadata":{"id":"c-_BNfapDy3y","colab_type":"code","colab":{},"outputId":"8858e5be-5ad5-4979-da7e-4ef51283a04d"},"cell_type":"code","source":["#with reduce()\n","from functools import reduce # in Python 3.\n","\n","def multiply(x,y):\n","    return x*y;\n","\n","product = reduce(multiply, lst)\n","print(product)\n"],"execution_count":0,"outputs":[{"output_type":"stream","text":["24\n"],"name":"stdout"}]},{"metadata":{"id":"PlBjfKeLDy33","colab_type":"text"},"cell_type":"markdown","source":["# 2. User-defined Functions"]},{"metadata":{"id":"-jG1cIkIDy33","colab_type":"text"},"cell_type":"markdown","source":["Functions that we define ourselves to do certain specific task are referred as user-defined functions"]},{"metadata":{"id":"U0R-nQZEDy35","colab_type":"text"},"cell_type":"markdown","source":["If we use functions written by others in the form of library, it can be termed as library functions."]},{"metadata":{"id":"qnW4EEEaDy36","colab_type":"text"},"cell_type":"markdown","source":["# Advantages"]},{"metadata":{"id":"BuTGBpe_Dy36","colab_type":"text"},"cell_type":"markdown","source":["1. User-defined functions help to decompose a large program into small segments which makes program easy to understand, maintain and debug.\n","\n","2. If repeated code occurs in a program. Function can be used to include those codes and execute when needed by calling that function.\n","\n","3. Programmars working on large project can divide the workload by making different functions."]},{"metadata":{"id":"bchAt3KsDy37","colab_type":"text"},"cell_type":"markdown","source":["# Example:"]},{"metadata":{"id":"Bl7T01heDy3-","colab_type":"code","colab":{},"outputId":"6dfc3c9d-6622-4219-9180-5367adb6b7b2"},"cell_type":"code","source":["def product_numbers(a, b):\n","    \"\"\"\n","    this function returns the product of two numbers\n","    \"\"\"\n","    product = a * b\n","    return product\n","\n","num1 = 10\n","num2 = 20\n","print \"product of {0} and {1} is {2} \".format(num1, num2, product_numbers(num1, num2))"],"execution_count":0,"outputs":[{"output_type":"stream","text":["product of 10 and 20 is 200 \n"],"name":"stdout"}]},{"metadata":{"id":"3t1WqaakDy4B","colab_type":"text"},"cell_type":"markdown","source":["# Python program to make a simple calculator that can add, subtract, multiply and division"]},{"metadata":{"id":"7VcPOrmLDy4E","colab_type":"code","colab":{},"outputId":"31adb3c1-11dd-4316-a355-ae44a54acf42"},"cell_type":"code","source":["def add(a, b):\n","    \"\"\"\n","    This function adds two numbers\n","    \"\"\"\n","    return a + b\n","\n","def multiply(a, b):\n","    \"\"\"\n","    This function multiply two numbers\n","    \"\"\"\n","    return a * b\n","\n","def subtract(a, b):\n","    \"\"\"\n","    This function subtract two numbers\n","    \"\"\"\n","    return a - b\n","\n","def division(a, b):\n","    \"\"\"\n","    This function divides two numbers\n","    \"\"\"\n","    return a / b\n","\n","print(\"Select Option\")\n","print(\"1. Addition\")\n","print (\"2. Subtraction\")\n","print (\"3. Multiplication\")\n","print (\"4. Division\")\n","\n","#take input from user\n","choice = int(input(\"Enter choice 1/2/3/4\"))\n","\n","num1 = float(input(\"Enter first number:\"))\n","num2 = float(input(\"Enter second number:\"))\n","if choice == 1:\n","    print(\"Addition of {0} and {1} is {2}\".format(num1, num2, add(num1, num2)))\n","elif choice == 2:\n","    print(\"Subtraction of {0} and {1} is {2}\".format(num1, num2, subtract(num1, num2)))\n","elif choice == 3:\n","    print(\"Multiplication of {0} and {1} is {2}\".format(num1, num2, multiply(num1, num2)))\n","elif choice == 4:\n","    print(\"Division of {0} and {1} is {2}\".format(num1, num2, division(num1, num2)))\n","else:\n","    print(\"Invalid Choice\")"],"execution_count":0,"outputs":[{"output_type":"stream","text":["Select Option\n","1. Addition\n","2. Subtraction\n","3. Multiplication\n","4. Division\n","Enter choice 1/2/3/43\n","Enter first number:12.2\n","Enter second number:2.3\n","Multiplication of 12.2 and 2.3 is 28.059999999999995\n"],"name":"stdout"}]},{"metadata":{"id":"aQZUmO9xDy4G","colab_type":"code","colab":{}},"cell_type":"code","source":[""],"execution_count":0,"outputs":[]}]}