Python Fundamentals - Basic | WeiYuan

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Python Fundamentals - Basic 給新⼿的 Python 程式設計 | WeiYuan

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§ 全端工程師 + 資料科學家 ST2DE 計劃發起人，擅長網站開發與資料科學的雙棲工程師，熟悉的語言是 Python 跟 JavaScript，喜歡用程式與技術的思維解決問題。 - 2018 總統盃黑客松冠軍隊伍 - 2017 資料科學愛好者年會(DSCONF) 講師 - 2017 行動科技年會(MOPCON) 講師 - 2016 微軟 Imagine Cup 台灣區冠軍 site: v123582.tw / line: weiwei63 mail: [email protected]

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Outline § Introduction § HelloWorld § Common Types & Operator § Flow Control § Function § Class § Exception § File IO 3

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Outline § Introduction § HelloWorld § Common Types & Operator § Flow Control § Function § Class § Exception § File IO 4

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Introduction § The Zen of Python: Beautiful, Explicit, Simple link § High-level and Interpreted programming language § OOP + FP multi-paradigm § Python 2.x or Python 3.x ? § Environment: `python --version` § Runtime： shell, command, jupyter/ipython, anaconda § Editor/IDE: sublime text, pycharm, spider(built in anaconda) § PIP: packages manager of python <- default § Pyenv, Vitrualenv <- need to install 5

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6 Explicit 清楚 Beautiful 漂亮 Simple 簡單

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7 Explicit 清楚 Beautiful 漂亮 Simple 簡單

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Python 2.x or Python 3.x ? 9

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Python 2.x or Python 3.x ? 10

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Python 2.x or Python 3.x ? 11 1. Python 團隊將於 2020 年 1 月 1 日停止支持 Python 2.7 2. Python 正式正名代表為 Python3

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13 選擇 Python 做為程式語言的兩個原因： ① 程式語法簡單好寫 ② 第三方資源豐富

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Python Ecosystem for Data Science § Request、beatifulsoup、Scrapy § NumPy、 SciPy、 Pandas § Matplotlib、 Seaborn、 Bokeh、 Plotly § Statsmodels、SciKit-Learn、xgboost § TensorFlow(Theano)、Pytorch、Keras § NLTK、Gensim 14

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Python Ecosystem for Data Science § Request、beatifulsoup、Scrapy =>資料收集 § NumPy、 SciPy、 Pandas => 資料前處理 § Matplotlib、 Seaborn、 Bokeh、 Plotly => 資料視覺化 § Statsmodels、SciKit-Learn、xgboost => 資料模型訓練 § TensorFlow(Theano)、Pytorch、Keras => 深度學習 § NLTK、Gensim => 自然語言與文本資料處理 15

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Runtime & Develop § 怎麼執行 Python 程式？ shell / command / Jupyter notebook § 在哪裡寫 Python 程式碼？ editor / IDE 16

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Python 環境、套件安裝與使用一個開發環境包含「程式語言執行環境」、「開發/編輯環境」、「第三方套件」。可能會存在版本或是專案上的差異，因此常見的管理工具有以下： § Anaconda 集成式開發軟體 § PIP 套件管理工具 § Pyenv 多版本Python管理工具 § Virtualenv 虛擬環境 17

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Python 環境、套件安裝與使用 18 § Anaconda是一個免費開源的Python和R語言的發行版本，用於計算科學，Anaconda致力於簡化包管理和部署。Anaconda的包使用軟體包管理系統Conda進行管理。

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pip 19

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20 #Note. 套件管理⼯具：替開發者下載、保存第三⽅套件，在程式中可以載⼊使⽤

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21 #Note. 套件管理⼯具：替開發者下載、保存第三⽅套件，在程式中可以載⼊使⽤ 1. 為什麼要用 pip？ 2. pip 是從哪裡下載套件的？ 3. 套件會被 pip 存放在哪？

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執行位置 – 方法一 22 1.從開始找到 Anaconda 2. 點選 Prompt，打開黑色視窗 3.開始輸入 pip 指令

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執行位置 – 方法二 23

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相關的開發管理工具 § PIP 套件管理工具 § Pyenv 多版本Python管理工具 § Virtualenv 虛擬環境 24

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Outline § Introduction § HelloWorld § Common Types & Operator § Flow Control § Function § Class § Exception § File IO 25

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Hello World Variable and Assign 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 #!/usr/bin/env python3 # -*- coding: utf-8 -*- # ['False', 'None' . . .] import this, keyword from keyword import kwlist from keyword import * keywords = kwlist if len(keywords) > 0: print(keywords) x = input("Input Something...") print("%s" % (x)) Import Library Encoding Declaration Comment Indentation and Block Input and Output

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Hello World 27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 #!/usr/bin/env python3 # -*- coding: utf-8 -*- # ['False', 'None' . . .] import this, keyword from keyword import kwlist from keyword import * keywords = kwlist if len(keywords) > 0: print(keywords) x = input("Input Something...") print("%s" % (x)) Encoding Declaration Comment

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Hello World 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 #!/usr/bin/env python3 # -*- coding: utf-8 -*- # ['False', 'None' . . .] import this, keyword from keyword import kwlist from keyword import * keywords = kwlist if len(keywords) > 0: print(keywords) x = input("Input Something...") print("%s" % (x)) Import Library § Library = module = package = a set of functions

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Hello World Variable and Assign 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 #!/usr/bin/env python3 # -*- coding: utf-8 -*- # ['False', 'None' . . .] import this, keyword from keyword import kwlist from keyword import * keywords = kwlist if len(keywords) > 0: print(keywords) x = input("Input Something...") print("%s" % (x)) § Case Sensitivity § Weekly/Loosely Typed

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Hello World 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 #!/usr/bin/env python3 # -*- coding: utf-8 -*- # ['False', 'None' . . .] import this, keyword from keyword import kwlist from keyword import * keywords = kwlist if len(keywords) > 0: print(keywords) x = input("Input Something...") print("%s" % (x)) Indentation and Block Spaces of Tab ?

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Hello World 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 #!/usr/bin/env python3 # -*- coding: utf-8 -*- # ['False', 'None' . . .] import this, keyword from keyword import kwlist from keyword import * keywords = kwlist if len(keywords) > 0: print(keywords) x = input("Input Something...") print("%s" % (x)) Input and Output

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Outline § Introduction § HelloWorld § Data Types & Operator § Flow Control § Function § Class § Exception § File IO 32

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Common Types & Operator 33 Primitive Container

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Primitive Types § Numeric type （int / float） § String type （str） § Boolean type （bool） 34

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Built-in Functions 35 1 2 3 4 5 6 type() dir() help() https://docs.python.org/3/library/functions.html

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Common Types & Operator 36 expression = operator (symbols)+ operand (variables)

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Common Types & Operator 37 expression = operator (symbols)+ operand (variables) arithmetic comparison logical bitwise

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Numeric type （int / float） 38 1 2 3 4 5 6 7 8 9 10 a = 20 a, b, c, d = 20, 5.5, True print(type(a)) # print(type(b)) # print(type(c)) # print(isinstance(a, int)) # True print(isinstance(b, int)) # False

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Numeric type （int / float） 39 1 2 3 4 5 6 7 8 9 10 11 4 + 2 4.0 + 2 4.0 + 2.0 2 / 5 2.0 / 5 2 / 5.0 2.0 / 5.0 2 // 5 2 % 5

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Numeric type （int / float） 40 1 2 3 4 5 6 7 8 9 10 11 # python2 w = 49 h = 163 bmi = 49 / (163/100)**2 print(bmi) # 49 # python3 w = 49.0 h = 163.0 bmi = 49 / (163/100)**2 print(bmi) # 18.4425...

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Try it! § #練習：Set the following variables to the corresponding values: 1. my_int to the value 7 2. my_float to the value 1.23 3. my_bool to the value True 41

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Try it! 42 1 2 3 4 5 6 7 8 9 10 11 1 + 3*2 # 1 + 3**2 # (1 + 3)*2 # 1 + 3 / 2 *2 # 1 + 3 // 2 *2 # 1 + 3 / 2 **2 # 1 + 3 // 2 **2 # int(1 + 3 / 2 *2) # float(1 + 3 // 2 **2) # § #練習：Set the following variables to the corresponding

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Try it! 43 1 2 3 4 5 6 7 8 9 10 11 a = input() b = input() ''' Your Code ''' print(‘The sum of ’, a, ‘and’ ,b , ‘is’, a+b) § #練習：Add two numbers

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Try it! 44 1 2 3 4 5 6 7 8 9 10 11 a = input() b = input() ''' Your Code ''' print(‘The sum of ’, a, ‘and’ ,b , ‘is’, a+b) § #練習：承上題，要如何改成 a, b, c, d 四個輸⼊：

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Try it! 45 1 2 3 4 5 6 7 8 9 10 11 num = 9 ''' Your Code ''' print('The square root of %0.3f is %0.3f' % (num ,num_sqrt)) § #練習：Find the Square Root

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Try it! 46 1 2 3 4 5 6 7 8 9 10 11 a = 5 b = 10 ''' Your Code ''' print(a, b) # 10, 5 § #練習：Swap Two Variables

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String Type - Operations 47 1 2 3 4 5 6 7 8 9 10 a = '12345' b = 'hello world' c = '\n' d = r'\n' e = '\\n' print(b + str(a) + c + d + e) print(b + str(a) + str(c) + str(d) + str(e))

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String Type - Index & Slice 48 1 2 3 4 5 6 7 8 9 10 s = 'hello world' s[0], s[1], s[-1] s[0:5], s[0:len(t)], s[:] s[1:5:2], s[::-1]

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String Type - Methods 49 1 2 3 4 5 6 7 8 9 10 b = 'hello world' dir(b)

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String Type 50 1 2 3 4 5 6 7 8 9 10 split() find() replace() len() lower() upper() isdigit() isnumeric() isalpha()

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§ Question：What is different among True, ‘True’, true ? 51

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Try it! § #練習：Write a Python program to get a string made of the first 2 and the last 2 chars from a given a string. If the string length is less than 2, return instead of the empty string. • Sample Input: w3resource • Sample Output: w3ce 52

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Try it! § #練習：將字串當中的 not that poor 換成 good 。 • Sample Input: The company is not that poor! • Sample Output: The company is good! 53

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Try it! § #練習：將字串當中的 not … poor 換成 good 。 • Sample Input: The company is not that poor! • Sample Output: The company is good! 54

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Try it! § #練習：⼀個網址的結構⼤概如圖所⽰，試著⽤ Python 分別把每個值取出來。 55

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#Note. Formatting String 56 1 2 3 4 5 6 7 8 9 10 a, b, sum = 2, 3, 5 '%s + %s = %s ' % (a, b, sum) '{} + {} = {} '.format(a, b, sum) '{x} + {y} = {z} '.format(x=a, y=b, z=sum) f'The sum of {a} and {b} is {sum}'

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#Note. Formatting String 57 1 2 3 4 5 6 7 8 9 10 a, b, sum = 2, 3, 5 '%s + %s = %s ' % (a, b, sum) '%d + %d = %d ' % (a, b, sum) '%f + %f = %f ' % (a, b, sum)

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#Note. Formatting String 58 1 2 3 4 5 6 7 8 9 10 a, b, c = ‘x’, ‘y’, ‘z’ '%s, %s, %s ' % (a, b, c) '%d, %d, %d ' % (a, b, c) '%f, %f, %f ' % (a, b, c)

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#Note. Formatting String 59 1 2 3 4 5 6 7 8 9 10 a, b, sum = 20.12, 30.123, 50.243 '%s + %s = %s ' % (a, b, sum) '%5d + %6d = %7d ' % (a, b, sum) '%5.1f + %6.2f = %8.3f ' % (a, b, sum)

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#Note. Formatting String 60 1 2 3 4 5 6 7 8 9 10 %s => string %d => decimal %f => float \n => new line \t => tab

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§ Question：Why do I use Formatting String? 61

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Container Types 62 § list [,] => mutable sequence § tuple (,) => immutable sequence § dict {:,} => mutable collection of key-value mapped element § set {,} => mutable collections of unique elements

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Container Types 63 § list [,] => mutable sequence § tuple (,) => immutable sequence § dict {:,} => mutable collection of key-value mapped element § set {,} => mutable collections of unique elements

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Container Types 64 § list [,] => mutable sequence § tuple (,) => immutable sequence § dict {:,} => mutable collection of key-value mapped element § set {,} => mutable collections of unique elements

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Container Types 65 § list [,] => # l = [1, 2, 3, 4], l[0] = 999 § tuple (,) => # t = (1, 2), t[0] = 999 § dict {:,} => # d = {1: 100, 2: 200}, d[1] § set {,} => # s = {1, 2, 3}

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List 66 § List – Operations § List – Index & Slice § List - Methods

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List - Operations 67 1 2 3 4 5 6 7 8 9 10 L = [1, 2, 3, 4] G = [3, 4, 5, 6] L + G # [1, 2, 3, 4, 3, 4, 5, 6] L – G # 不存在 L * 2 # [1, 2, 3, 4, 1, 2, 3, 4] L / 2 # 不存在

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List – Index & Slice 68 1 2 3 4 5 6 7 8 9 10 L = [1, 2, 3, 4, 5, 6] L[0], L[1], L[-1] L[0] = 999 L[0:5], L[0:len(L)], L[:] L[1:5:2], L[::-1]

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§ Question：How does arithmetical operation with string? 69

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List - Methods 70 1 2 3 4 5 6 7 8 9 10 my_list = [2] # [2] my_list.append(2) # [2, 2] my_list.extend([2]) # [2, 2, 2] my_list.insert(0, 3) # [3, 2, 2, 2] my_list.pop() # [3, 2, 2] my_list.remove(2) # [3, 2] my_list.sort() # [2, 3] my_list.reverse() # [3, 2]

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List - Operations 71 1 2 3 4 5 6 7 8 9 10 my_list.count(2) # 1 len(my_list) # 2 sum(my_list) # 5 ‘2, 3’.split(‘, ’) # [2, 3] ', '.join([2, 3]) # '2, 3'

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Try it! § #練習：有一個列表，其中包括 10 個元素，例如這個列表是 [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]，要求將最右邊的 0 移到最左邊，結果會變成 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] 72

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Try it! § #練習：有一個列表，其中包括 10 個元素，例如這個列表是 [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]，要求將最左邊的 1 移到最右邊，結果會變成 [2, 3, 4, 5, 6, 7, 8, 9, 0, 1] 73

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#Discussion 1. append, extend, + 三種方法有什麼不一樣？ 2. reversed(L), L.reverse(), [::-1] 3. sorted(L), L.sort() 74

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Try it! § #練習：Write a Python program to replace the last element in a list with another list. • Sample Input: num1 = [1, 3, 5, 7, 9, 10], num2 = [2, 4, 6, 8] • Sample Output: [1, 3, 5, 7, 9, 2, 4, 6, 8] 75

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Tuple 76 § Tuple – Operations § Tuple – Index & Slice § Tuple – Destructuring & Swaping

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Tuple - Operations 77 1 2 3 4 5 6 7 8 9 10 t1 = (1, 2, 3) t1 = (4, 5, 6) t1 + t2 t1 * 2

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Tuple – Index & Slice 78 1 2 3 4 5 6 7 8 9 10 t = (1, 2, 3, 4, 5, 6) t[0], t[1], t[-1] t[0] = 999 t[0:5], t[0:len(t)], t[:] t[1:5:2], t[::-1]

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§ Question：How does arithmetical operation with string & list? 79

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Destructuring & Swaping 80 1 2 3 4 5 6 7 8 9 10 (a, b) = my_list (a, b) = (b, a)

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Try it! § #練習：Swap Two Variables 81 1 2 3 4 5 6 7 8 9 10 11 a = 5 b = 10 ''' Your Code ''' print(a, b) # 10, 5

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Dictionary 82 § Dictionary – Operations § Dictionary – Unordered to Ordered § Dictionary – Key Error

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Dictionary – Operations 83 1 2 3 4 5 6 7 8 9 10 my_dict = {'Mark': 1, 'test': 0} print(my_dict[’Mark’]) # 1 print(my_dict[0]) my_dict['Mary'] = 2 # {'Mark': 1, 'test': 0, ‘Mary’: 2} del my_dict['test']

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Dictionary – Unordered to Ordered 84 1 2 3 4 5 6 7 8 9 10 my_dict.items() # dict_items([('Mark', 1), ('Mary', 2) ]) my_dict.keys() # dict_keys(['Mark', 'Mary']) my_dict.values() # dict_values([1, 2])

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Dictionary – Key Error 85 1 2 3 4 5 6 7 8 9 10 my_dict['Tom'] # Traceback (most recent call last): # File "", line 1, in # KeyError: ‘Tom’ my_dict.get('Tom', ''), my_dict # '', {'Mark': 1, 'test': 0} my_dict.setdefault('Tom', 3), my_dict # 3, {'Tom': 3, 'Mark': 1, 'test': 0}

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Try it! § #練習： Write a Python program to concatenate following dictionaries to create a new one 86 1 2 3 4 5 6 7 8 9 10 11 # Input: dic1={1:10, 2:20} dic2={3:30, 4:40} dic3={5:50, 6:60} ''' Your Code ''’ # Output: {1: 10, 2: 20, 3: 30, 4: 40, 5: 50, 6: 60}

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Try it! § #練習：Write a Python program to check if a given key already exists in a dictionary. § 87 1 2 3 4 5 6 7 8 9 10 11 # Input: d = {1: 10, 2: 20, 3: 30, 4: 40, 5: 50, 6: 60} key = input() ''' Your Code ''' # Output: Yes, the key is in this dict. or # No, the key is not in this dict.

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Set 88 § Set – Operations

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Set – Operations 89 1 2 3 4 5 6 7 8 9 10 dmins = {'admin'} users = {'admin', 'user1', 'user2'} 'Justin' in admins # False admins & users # {'admin'} admins | users # {'admin', 'user1', 'user2'} admins - users # {} users – admins # {‘user1’, ‘user2’} admins ^ users # {user1, user2}

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Try it! § #練習： Illustrate Different Set Operations 90 1 2 3 4 5 6 7 8 9 10 11 # define three sets E, N = {0, 2, 4, 6, 8}, {1, 2, 3, 4, 5} print("Intersection of E and N is", E & N) # 2, 4 print("Union of E and N is",E | N) # 0 1 2 3 4 5 6 8 print("Difference of E and N is",E - N) # 1 3 5 print("Symmetric difference of E and N is",E ^ N) # 0 1 3 5 6 8

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Try it! § #練習： Remove the repeated elements from the list, and sort it Decreasingly. 91 1 2 3 4 5 6 7 8 9 10 11 l = [1, 1, 3, 9, 7, 8, 8, 8] ''' Your Code ''' # Output: [9, 8, 7, 3, 1]

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Container Types 92 § list [,] => Operations / Index & Slice / Methods § tuple (,) => Operations / Index & Slice /Destructuring & Swaping § dict {:,} => Operations / Unordered to Ordered / Key Error § set {,} => Operations

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93 § Mutable objects • list, dict, set § Immutable objects • int, float, complex, string, tuple Reference: https://www.linkedin.com/pulse/mutable-vs-immutable-objects-python-megha-mohan Im vs Mutable ?

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94 Reference: https://www.linkedin.com/pulse/mutable-vs-immutable-objects-python-megha-mohan

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tuple vs list？ § slower but more powerful than tuples. § Lists can be modified, and they have lots of handy operations we can perform on them. § Tuples are immutable and have fewer features. § To convert between tuples and lists use the list() and tuple() functions: • li = list(tu) • tu = tuple(li) 95

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iterator, iterable, iteration 96 Reference: http://nvie.com/posts/iterators-vs-generators/

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iterator, iterable, iteration 97 1 2 3 4 5 6 7 8 9 10 11 12 13 14 list = [1, 2, 3] iterator = iter(list) import sys sys.getsizeof(list) sys.getsizeof(iterator) for i in list: print(i) for i in iterator: print(i) print(next(iterator))

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iterator, iterable, iteration 98 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 def f(): i = 1 return i def g(): i = 1 yield i i = 2 yield i a = f() b = g() print(a) print(next(b))

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bulit-in method 99 1 2 3 4 5 6 7 8 dir(list) # ['append', 'clear', 'copy', 'count', 'extend', 'index',# 'insert', 'pop', 'remove', 'reverse', 'sort'] help(list.extend) # extend(...) # L.extend(iterable) -> None # extend list by appending elements from the iterable Reference: https://docs.python.org/3/library/functions.html

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Try it! § #練習：要求使⽤者輸⼊ n ，印出從 n 平⽅的對數值（Log） • hint：引入一個 math 的函式庫，並且利用 dir 與 math 查看 log 函式怎麼使用 100

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Outline § Introduction § HelloWorld § Common Types & Operator § Flow Control § Function § Class § Exception § File IO 101

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Flow Control § if - elif - else § while § for in § break, continue § range(), zip(), enumerate() 102

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Common Types & Operator § Numeric type • int, float, bool, complex • expression => operator + operand § String type § Container type • list, tuple, dict, set 103 § expression = operator + operand (varibles) • arithmetic, comparison arithmetic comparison logical bitwise

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Flow Control § Logical Operator § Comparison Operator 104 1 2 3 3 is 2, 3 is not 2 True and False, True or False 3 in [1, 2, 3, 4] 1 2 > 2, 2 >= 2, 2 == 2, 2 != 2

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Flow Control § Logical Operator => return Boolean § Comparison Operator => return Boolean 105 1 2 3 3 is 2, 3 is not 2 True and False, True or False 3 in [1, 2, 3, 4] 1 2 > 2, 2 >= 2, 2 == 2, 2 != 2

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What it truth? 106

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What it truth? 107

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Flow Control § if - elif - else § while § for in § break, continue § range(), zip(), enumerate() 108 1 2 3 4 5 6 7 8 9 if condition: ... elif condition: ... else: ... a = ... if condition else ...

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109 Reference: http://swcarpentry.github.io/training-course/2013/03/concept-map-conditional-statements-python/ § operator • boolean/logical • comparison

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Flow Control § if - elif - else § while § for in § break, continue § range(), zip(), enumerate() 110 1 2 while condition: ....

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Flow Control § if - elif - else § while § for in § break, continue § range(), zip(), enumerate() 111 1 2 3 4 5 for i in [...]: ... a = [i for i in [...]] # list b = (i for i in [...]) # generator

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Try it! § #練習：有一個列表，其中包括 10 個元素，例如這個列表是 [1, 2, 3, 4, 5, 6, 7, 8, 9, 0],要求將列表中的每個元素一次向前移動一個位置，第一個元素到列表的最後，然後輸出這個列表。最終樣式是 [2, 3, 4, 5, 6, 7, 8, 9, 0, 1]，如果要把偶數放前⾯，奇數放後⾯該怎麼做？結果像是 [0, 2, 4, 6, 8, 1, 3, 5, 7, 9] 112

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Try it! § #練習：在數學中，用 n! 來表示階乘，例如，4! =1×2×3×4 =24。請寫一個程式，讓使用者輸入 n，印出 n! 1. 用 for 迴圈完成 2. 用 while 迴圈完成 113

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Try it! § #練習：如果將⼀句話作為⼀個字符串，那麼這個字符串中必然會有空格（這裡只是討論英⽂），⽐如“How are you?”，但有的時候，會在兩個單詞之間多⼤⼀個空格。現在的任務是，如果⼀個字符串中有連續的兩個空格，請把它刪除。 114

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Try it! § #練習："Please count the character here." 115 1 2 3 4 5 6 7 8 9 10 # {'r': 3, 'c': 3, 't': 3, ' ': 4, 'n': 1, 'u': 1, 'h': 3, 'e': 6, 'l': 1, 'o': 1, 'a': 3, 's': 1, 'P': 1, '.': 1}

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Try it! § #練習："Here are UPPERCASE and lowercase chars." 116 1 2 3 4 5 6 7 8 9 10 # {'c': ['c', 'c'], 'R': ['R'], 'w': ['w'], ' ': [' ', ' ', ' ', ' ', ' '], '.': ['.'], 'n': ['n'], 'H': ['H'], 'P': ['P', 'P'], 'h': ['h'], 'S': ['S'], 'e': ['e', 'e', 'e', 'e', 'e'], 'l': ['l'], 'E': ['E', 'E'], 'U': ['U'], 'a': ['a', 'a', 'a', 'a'], 'A': ['A'], 'o': ['o'], 'C': ['C'], 'r': ['r', 'r', 'r', 'r'], 'd': ['d'], 's': ['s', 's']}

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Try it! § #練習：畫各種三⾓形與變形 117 * ** *** **** * ** *** **** * *** ***** ******* * *** ***** ******* ********* ******* ***** *** *

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§ https://leetcode.com/problems/two-sum/description/ 118

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Flow Control § if - elif - else § while § for in § break, continue § range(), zip(), enumerate() 119

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Flow Control § if - elif - else § while § for in § break, continue § range(), zip(), enumerate() 120 1 2 3 4 5 6 7 8 for i in range(1, 3): print(i) for i, j in zip([a, b, c], [1, 2, 3]): print(i, j) for i,j in enumerate([a, b, c]): print(i, j)

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More zip() … 121 1 2 3 4 5 6 7 8 9 10 result1 = [2, 4, 6, 8] result2 = [11, 13, 15, 17] for i, j in zip(result1, result2) print(i + j) # 2 11 # 4 13 # 6 15 # 8 17

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More zip() … 122 1 2 3 4 5 6 7 8 9 10 11 12 13 result3 = [(2, 11), (4, 13), (6, 15), (8, 17)] for i in zip(*result3): print(i) # (2, 4, 6, 8) # (11, 13, 15, 17) for i in map(list,zip(*result3)): print(i) # [2, 4, 6, 8] # [11, 13, 15, 17]

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Try it! § #練習：建⽴⼀個 1 - 10 平⽅的數列。 123

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Try it! § #練習：有兩個列表，分別是：a = [1,2,3,4,5]，b = [9,8,7,6,5]，要計算這兩個列表中對應元素的和。 124

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Try it! § #練習：有⼀個字典，myinfor = {"name":"qiwsir","site":"qiwsir.github.io","lang":"python"}, 將這個字典變換成：infor = {"qiwsir":"name","qiwsir.github.io":"site","python":"lang"} 125

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Try it! § #練習：按照下⾯的要求實現對列表的操作，產⽣⼀個列表，其中有40個元素，每個元素是0到100的⼀個隨機整數如果這個列表中的數據代表著某個班級40⼈的分數，請計算成績低於平均分的學⽣⼈數，並輸出對上⾯的列表元素從⼤到⼩排序 126

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Try it! § #練習：承上題，想要對分數進⾏調整，不及格的⼈將原始分數開根號乘以⼗（但最⾼不可以超過 60 分），及格者不變。 127

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Outline § Introduction § HelloWorld § Common Types & Operator § Flow Control § Function § Class § Exception § File IO 128

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Function 129 1 2 3 4 5 6 7 8 9 max1 = a if a > b else b... max2 = x if x > y else y... a = 123 b = 234 // declare funcetion def max(a, b): return a if a > b else b // call function max(10, 20) maximum = max maximum(10, 20) # 20

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Basic Method for Call Function 130 1 2 3 4 5 6 7 def f(x=100, y=200): return x, y f(1, 2) f(y=2, x=1) f(*(1, 2)) f(**{y=2, x=1})

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Try it! § #練習：寫⼀個計算平⽅的函式。 131

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Try it! § #練習：寫⼀個計算平⽅根的函式。 132

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Try it! § #練習：寫⼀個回傳⼀次⽅，⼆次⽅，…，到指定次⽅的函式。 133

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*args 134 1 2 3 4 5 6 7 8 9 10 def foo(*args): print(args) foo(1,2,3) # (1, 2, 3) foo("qiwsir","qiwsir.github.io","python") # ('qiwsir', 'qiwsir.github.io', 'python') foo("qiwsir",307,["qiwsir",2],{"name":"qiwsir"}) # ('qiwsir', 307, ['qiwsir', 2], {'lang': 'python'})

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**kargs 135 1 2 3 4 5 def foo(**kargs): print(kargs) foo(a=1,b=2,c=3) # {'a': 1, 'c': 3, 'b': 2}

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type1 + type2 + type3 136 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 def foo(x,y,z,*args,**kargs): print(x) print(y) print(z) print(args) print(kargs) foo('qiwsir',2,"python") # qiwsir# 2 # python# ()# {} foo(1,2,3,4,5) # 1# 2# 3# (4, 5)# {} foo(1,2,3,4,5,name="qiwsir") # 1# 2# 3# (4, 5)# {'name': 'qiwsir'}

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137 Reference: http://swcarpentry.github.io/training-course/2013/05/concept-map-python-functions/

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Try it! § #練習：以下程式會如何輸出？ 138 1 2 3 4 5 6 7 8 9 10 11 12 def foo(x,y=‘hello’,*targs,**dargs): print "x==>",x print "y==>",y print "targs_tuple==>",targs print "dargs_dict==>",dargs foo("1x") foo("1x","2y") foo("1x","2y","3t1","3t2") foo("1x","2y","3t1","3t2",d1="4d1",d2="4d2")

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Try it! § #練習：寫⼀個輸⼊ N 個數字，回傳總和的函式。 139

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Try it! § #練習：印出 1~100 有哪些質數 140

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Outline § Introduction § HelloWorld § Common Types & Operator § Flow Control § Function § Class § Exception § File IO 141

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Software Engineering 142 Procedural Programming Modular Programming Objective Orient Programming Functional Programming

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Software Engineering 143 Modular Programming Objective Orient Programming

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Class and Object 144

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145 abstract instance

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146 class object

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147 class object State Behavior

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148 class object Properties method

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OOP Concept § Abstraction § Encapsulation => public, private § Inheritance § Polymorphism => 不同的類別，有相同的 method § Overloading => 一個類別中相同的 method ，有不同的行為 § Overriding => 父子相同的 method，改寫成不同的行為 149

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Inheritance § base classes § derived class 150

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Class Objects 151 1 2 3 4 5 6 7 8 class MyClass: """A simple example class""" i = 12345 def f(self): return 'hello world %s' % (self.i)

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Class Objects 152 1 2 3 4 5 6 7 8 class MyClass: """A simple example class""" def __init__(self, i): self.i = i def f(self): return 'hello world %s' % (self.i)

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Class and Object 153 1 2 3 4 5 6 7 8 class Animal: def __init__(self, name): self.name = name def call(): return ‘汪汪’ a = Animal('動物') print(a.name) print(a.call())

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154 1 2 3 4 5 6 7 8 9 10 class BankAccount: type = 'Normal Account' def __init__(self, name): self.userName = name self.balance = 0.0 def __str__(self): return self.name 11 12 13 14 15 16 17 18 19 20 21 22 def showBalance(self): print self.balance return def withdrawMoney(self, amount): self.balance -= amount self.check() return def depositMoney(self, amount): self.balance += amount return def check() Creating a Class

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155 1 2 3 4 5 6 7 8 9 10 object1 = BankAccount("Im 1") object1.userName object1.depositMoney(100) print object1.balance object1.showBalance() print object1.type Create an Object 1 2 3 4 5 6 7 8 9 10 object2 = BankAccount("Im 2") object2.userName object2.depositMoney(200) print object2.balance object2.showBalance() print object2.type

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156 1 2 3 4 5 6 7 8 9 10 account3 = BankAccount() print(account3.__class__) print(type(account3)) string = 'Cat' print(string.__class__) print(type(string)) Create an Object

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Try it! § #練習：建⽴⼀個 Student 的類別，要包含姓名、性別、年齡，也要可以修改資料。 § class student() § det __init__(self, name, sex, age): § selt.name = name. § … 157

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Try it! § #練習：利⽤上述建⽴的類別，宣告幾個物件，並放到⼀個 dict 保存。 § TomObj = student(‘Tom’, ‘male’, 22) § stduents = {‘Tom’: TomObj , ‘Mary’: obj} § stduents.Tom.age § stduents.Mary.age 158

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Inherit 160 1 2 3 4 5 6 7 8 9 1 0 class Dog(Animal): def __init__(self, name, age): super().__init__(name) self.age = age # override def call(): print('汪汪汪') def call(ishungry): print(’T____T') d = Dog('小白', 13) print(d.name) 1 2 3 4 5 6 7 8 class Animal: def __init__(self, name): self.name = name def call(): return ‘汪汪’ a = Animal('動物') print(a.name) print(a.call())

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Inherit 161 1 2 3 4 5 6 7 8 9 1 0 class Cat(Animal): def __init__(self, name, age): super().__init__(name) self.age = age # override def call(): print(’喵喵喵') d = Dog(‘小花', 13) print(d.name) 1 2 3 4 5 6 7 8 class Animal: def __init__(self, name): self.name = name def call(): return ‘汪汪’ a = Animal('動物') print(a.name) print(a.call())

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Inherit 162 1 2 3 4 5 6 7 8 9 10 class ExecutiveAccount( BankAccount ): def requestCredit(self, amount): self.balance += amount executive = ExecutiveAccount()

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Private 164 1 2 3 4 5 6 7 8 9 10 class Human: def __init__(self,h=0,w=0): self.height=h self.weight=w def BMI(self): return self.weight / ((self.height/100)**2) a = Human(180,80) print(a.height,a.weight) print(a.BMI())

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Private 165 1 2 3 4 5 6 7 8 9 10 class Human: def __init__(self,h=0,w=0): self.__height=h self.__weight=w def __BMI(self): return self.__weight / ((self.__height/100)**2) a = Human(180,80) print(a.__height,a.__weight) print(a.__BMI())

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Private 166 1 2 3 4 5 6 7 8 9 10 class Human: def __init__(self,h=0,w=0): self.__height=h self.__weight=w def __BMI(self): return self.__weight / ((self.__height/100)**2) def getBMI(self): return self.__BMI() a = myclass.Human(180,80) print(a.getBMI())

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Outline § Introduction § HelloWorld § Common Types & Operator § Flow Control § Function § Class § Exception § File IO 167

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Error Exception 168 1 2 3 4 5 6 7 8 9 10 11 12 13 14 10 * (1/0) 4 + spam*3 '2' + 2

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Error Exception 169 1 2 3 4 5 6 7 8 9 10 11 12 13 14 10 * (1/0) # Traceback (most recent call last): # File "", line 1, in ZeroDivisionError: division by zero 4 + spam*3 # Traceback (most recent call last): # File "", line 1, in NameError: name 'spam' is not defined '2' + 2 # Traceback (most recent call last): # File "", line 1, in TypeError: Can't convert 'int' object to str implicitly

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try-except 170 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 try: x = input("the first number:") y = input("the second number:") r = float(x)/float(y) print(r) except Exception as e: print(e) the first number: 2 the second number: 0 # float division by zero the first number: 2 the second number: a # could not convert string to float: a the first number: 4 the second number: 2 # 2.0

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Finally 171 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 try: do something except: raise NameError('HiThere') do something finally do something try: file = open("test.py") except: print('Read file error') finally: file.close()

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Outline § Introduction § HelloWorld § Common Types & Operator § Flow Control § Function § Class § Exception § File IO 172

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File Write 173 1 2 3 fh = open("example.txt", "w") fh.write(”hello world") fh.close()

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File Read 174 1 2 3 fh = open("example.txt", ”r") fh.read() fh.close()

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With 175 1 2 3 4 5 with open("example.txt", "w") as fh: fh.write(”hello world") with open("example.txt", "r") as fh: fh.read()

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mode 176 r 以只读⽅式打开⽂件。⽂件的指针将会放在⽂件的开头。这是默认模式。 r+ 打开⼀个⽂件⽤于读写。⽂件指针将会放在⽂件的开头。 w 打开⼀个⽂件只⽤于写⼊。如果该⽂件已存在则将其覆盖。如果该⽂件不存在，创建新⽂件。 w+ 打开⼀个⽂件⽤于读写。如果该⽂件已存在则将其覆盖。如果该⽂件不存在，创建新⽂件。 a 打开⼀个⽂件⽤于追加。如果该⽂件已存在，⽂件指针将会放在⽂件的结尾。也就是说，新的内容将会被写⼊到已有内容之后。如果该⽂件不存在，创建新⽂件进⾏写⼊。 a+ 打开⼀个⽂件⽤于读写。如果该⽂件已存在，⽂件指针将会放在⽂件的结尾。⽂件打开时会是追加模式。如果该⽂件不存在，创建新⽂件⽤于读写。

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Thanks for listening. 2017/08/07 (Tue.) Fundamental Python - Basic Wei-Yuan Chang [email protected] v123582.github.io