Python Tutorial

What is Python?

History

Python 是一個由 Guido van Rossum 在 1991 年 2 月釋出的程式語言， 發展至今大約過了 20 餘年， 廣泛使用於科學計算、網頁後端開發、系統工具等地方

Python 是源自於當時 Guido van Rossum 觀賞的 BBC 喜劇 「Monty Python's Flying Circus」

Features

• 直譯式
• 物件導向
• 高階語言

Python2 & Python3

Python3在2008年12月3日首次釋出，與Python2不相容。

Python2 將在2020年後停止維護

所以～學新的比較潮(?)

Ubuntu

$ sudo apt-get install python3

Centos

$ sudo yum install yum-utils
$ sudo yum-builddep python
$ curl -O https://www.python.org/ftp/python/3.5.0/Python-3.5.0.tgz

$ tar xf Python-3.5.0.tgz
$ cd Python-3.5.0
$ ./configure
$ make
$ sudo make install

Windows

零基礎學網頁爬蟲 01_安裝Python環境

Mac OSX

$ brew install python3

A space for storing data

Example

>>> x = 123
>>> x
123
>>> y = 3.14
>>> y
3.14

Data types

• int
• float
• str
• list
• dict
• …

How to know the data type?

type()

>>> type(1)
<class 'int'>
>>> type(1.5)
<class 'float'>
>>> type("Hello")
<class 'str'>
>>> type([1,2,3])
<class 'list'>

list() element access

>>> friends = ["Joe","John","Jack"]
>>> friends[0]
Joe
>>> friends[2]
Jack

Integer(整數運算)

>>> 1 + 1
2
>>> 1 - 1
0
>>> 3 * 4
12
>>> 4 // 2
2
>>> 5 % 3
2

Floating Point(浮點數、小數運算)

>>> 1.1 + 1.2
2.3
>>> 1.5 - 3.5
-2.0
>>> 5.0 * 3.0
15.0
>>> 4.0 / 1.5
2.666666666665
>>> 6 / 3
2.0

Power (指數運算)

>>> 5 ** 2
25
>>> 5 ** 0.5 #5的平方根
2.23606797749979
>>> 27 ** (1/3) # 27的立方根

>>> x = 5
>>> x += 1
>>> x
6
>>> x += 4
>>> x
10
>>> x *= 2
>>> x
20

String(字串)

>>> msg = "Hello" + " world!"
>>> msg
Hello world!

List(列表)

>>> [2,3] + [4,6]
[2,3,4,6]

>>> 1 < 2
True
>>> 1 > 2
False
>>> 1 == 2
False
>>> 1 != 2
True
>>> 1 >= 2
False
>>> 1 <= 2
True

>>> x = 5
>>> y = 12
>>> x >= 1 and x <= 10
True
>>> y <= 10 or y >= 15
False
>>> not True
False
>>> not False
True

Output

>>> print(5)
5
>>> x = 60
>>> print(x)
60
>>> y = "Hello"
>>> print(y)
Hello
>>> print(y * 4)
HelloHelloHelloHello

Input

>>> x = input("Input something: ")
Input something: 123
>>> print(x)
123
>>> x = input("Input something: ")
Input something: Something
>>> print(x)
Something

Install module

pip3 install <Module name>

Using Standard Library

import random
 
print(random.choice([1,2,3,4,5]))

出題目

從 0-9選出四個隨機排列的數字
用 random module

import random
 
def generate_problem():
    candidate = [0,1,2,3,4,5,6,7,8,9]
    candidate = random.sample(candidate,4)
    return candidate
 

主要結構

 
problem = generate_problem()
print(problem)
guess = input("Input your guess: ")
result = check_correct(problem,guess)
print( "{}A{}B".format(result[0],result[1]) )
if result[0] == 4:
    print("Congratulation! Your guess is correct.")
else:
    print("Wrong answer. Try again :)")
 

怎麼確認答案對不對

def check_correct(problem,guess):
    for idx1,num in enumerate(problem):
        print(idx,num)
        

def check_correct(problem,guess):
    print(guess,type(guess))
    for idx1,num in enumerate(problem):
        print(idx,num)
        

def check_correct(problem,guess):
    for idx2,digit in enumerate(guess):
        print(idx,digit,type(digit))
    for idx1,num in enumerate(problem):
        print(idx,num)
        

把string換成integer

>>> s = "123"
>>> int(s)
123

def check_correct(problem,guess):
    for idx2,digit in enumerate(guess):
        print(idx,type(int(digit)))
    for idx1,num in enumerate(problem):
        print(idx,num)

怎麼確認答案正不正確

確認答案的每一個數字有沒有在猜測的數字裡

再確認位置是不是正確的

def check_correct(problem,guess):
    for idx1,num in enumerate(problem):
        for idx2,digit in enumerate(guess):
            if num == digit:
                print("Match")
    

def check_correct(problem,guess):
    A = 0
    B = 0
    for idx1,num in enumerate(problem):
        for idx2,digit in enumerate(guess):
            if num == digit:
                if idx1 == idx2:
                    A += 1
                else:
                    B += 1
    return [A,B]

只能猜一次XD

用while loop解決

game_over = False
problem = generate_problem()
print(problem)
while not game_over:
    guess = input("Input your guess: ")
    result = check_correct(problem,guess)
    print("{}A{}B".format(result[0],result[1]))
    if result[0] == 4:
        print("Congratulation! Your guess is correct.")
        game_over = True
    else:
        print("Wrong answer. Try again :)")

import random
def generate_problem():
    candidate = [0,1,2,3,4,5,6,7,8,9]
    candidate = random.sample(candidate,4)
    return candidate

def check_correct(problem,guess):
    A=0
    B=0
    for idxP,num in enumerate(problem):
        for idxG,digit in enumerate(guess):
            if int(digit) == num:
                if idxP == idxG:
                    A += 1
                else:
                    B += 1
    return [A,B]

game_over = False
problem = generate_problem()
print(problem)
while not game_over:
    guess = input("Input your guess: ")
    result = check_correct(problem,guess)
    print("{}A{}B".format(result[0],result[1]))
    if result[0] == 4:
        print("Congratulation! Your guess is correct.")
        game_over = True
    else:
        print("Wrong answer. Try again :)")