Codecademy.com学习Python

编程由Python入门。

第一步Codecademy网站的Python学习课程。（共15小时，预计一周（6.22-6.27）完成，6.28做总结）

Codecademy界面很清爽,语言为英文，正好适合适应英文学习环境，作为入门是不错的选择。

不知道下面的MIT、Harvard的网络课程会怎么样（安排自《编程入门指南v1.4》）。

 

7月1日Coursera.org上的北京大学程序设计专项课程就要开始了。去完成这个系列。

 

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Python学习笔记

1.Python Syntax(语法)

　　Variables(变量)

　　Calculator: + - * / % **

 

2.String and Console Output(字符串与控制台输出)

　　print(打印)

　　datetime

 

3.Conditionals & Control Flow(条件语句与控制流)

　　Comparators(比较)

　　Boolean Operators(布尔判断)(inlcude and,or,not)

　　Conditional Statements(条件语句)(include if,elif,else)

 

　　游戏PygLatin程序 (my first Python Program)

　　代码：

pyg = 'ay'

original = raw_input('Enter a word:')

if len(original) > 0 and original.isalpha():
    print original
    word=original.lower()
    first=word[0]
    new_word=word+first+pyg
    new_word=new_word[1:len(new_word)]
    print new_word
else:
    print 'empty'

　　所学到的新知识

　　1.isalpha()函数 用于判断是否为纯字母字符串

　　2.字符串中提取从几位到几位的字符 string[x:x] (x代表数字)

 

4.Functions

　　Function Syntax

　　　　Fuction Junction

　　　　Parameters and Arguments(参数)

　　Importing Modules

　　　　Three Way: 1). import math

　　　　　　　　　　 2).from math import sin

　　　　　　　　　    3).from math import *   #including ALL in math

　　Build-in Functions

　　　　.upper()　　.lower()　　len()　　str()　　max()　　min()　　type()　　abs()

 

 

Taking a Vacation:)

def hotel_cost(nights):
    return 140*nights

def plane_ride_cost(city):
     if city=="Charlotte":
         return 183
     elif city=="Tampa":
         return 220
     elif city=="Pittsburgh":
         return 222
     elif city=="Los Angeles":
         return 475
         
def rental_car_cost(days):
    cost=40*days
    if days>=7:
        return cost-50
    elif days>=3:
        return cost-20
    else:
        return cost
        
def trip_cost(city,days,spending_money):
    return rental_car_cost(days)+hotel_cost(days)+plane_ride_cost(city)+spending_money
    
print trip_cost("Los Angeles",5,600)

 

5. Lists and Dictionaries

　　Lists(列表，类似数组)

 

　　Dictionaries(字典)

　　　　including keys and things

　　　　

 

　　.sort() 排序函数

 

 

　　A Day at the Supermarket

shopping_list = ["banana", "orange", "apple"]

stock = {
    "banana": 6,
    "apple": 0,
    "orange": 32,
    "pear": 15
}
    
prices = {
    "banana": 4,
    "apple": 2,
    "orange": 1.5,
    "pear": 3
}

# Write your code below!
def compute_bill(food):
    total=0
    for it in food:
        if stock[it]>0:
            total+=prices[it]
            stock[it]-=1
    return total
    
print compute_bill(shopping_list)

 

　　Practice:Students and Class Grade

lloyd = {
    "name": "Lloyd",
    "homework": [90.0, 97.0, 75.0, 92.0],
    "quizzes": [88.0, 40.0, 94.0],
    "tests": [75.0, 90.0]
}
alice = {
    "name": "Alice",
    "homework": [100.0, 92.0, 98.0, 100.0],
    "quizzes": [82.0, 83.0, 91.0],
    "tests": [89.0, 97.0]
}
tyler = {
    "name": "Tyler",
    "homework": [0.0, 87.0, 75.0, 22.0],
    "quizzes": [0.0, 75.0, 78.0],
    "tests": [100.0, 100.0]
}

# Add your function below!
def average(numbers):
    total=sum(numbers)
    total=float(total)
    return total/len(numbers)
    
def get_average(student):
    homework=average(student["homework"])
    quizzes=average(student["quizzes"])
    tests=average(student["tests"])
    return 0.1*homework+0.3*quizzes+0.6*tests
    
def get_letter_grade(score):
    if score>=90:
        return "A"
    elif score>=80:
        return "B"
    elif score>=70:
        return "C"
    elif score>=60:
        return "D"
    else:
        return "F"
        
def get_class_average(students):
    results=[]
    for student in students:
        results.append(get_average(student))
    return average(results)
        
print get_letter_grade(get_average(lloyd))
print get_class_average([lloyd,alice,tyler])
print get_letter_grade(get_class_average([lloyd,alice,tyler]))

 

6. Lists and Functions

　　

　　用Python编写的第一个游戏:Battleship!

from random import randint

board = []

for x in range(5):
    board.append(["O"] * 5)

def print_board(board):
    for row in board:
        print " ".join(row)

print "Let's play Battleship!"
print_board(board)

def random_row(board):
    return randint(1, len(board))

def random_col(board):
    return randint(1, len(board[0]))

ship_row = random_row(board)
ship_col = random_col(board)

for turn in range(4):
    guess_row = int(raw_input("Guess Row:"))
    guess_col = int(raw_input("Guess Col:"))

    if guess_row == ship_row and guess_col == ship_col:
        print "Congratulations! You sunk my battleship!"
        board[ship_row-1][ship_col-1] = "R"
        print_board(board)
        break
    else:
        if (guess_row < 1 or guess_row > 5) or (guess_col < 1 or guess_col > 5):
          print "Oops, that's not even in the ocean."
        elif board[guess_row-1][guess_col-1] == "X":
            print "You guessed that one already."
        else:
            print "You missed my battleship!"
            board[guess_row-1][guess_col-1] = "X"
    print "Turn",turn+1
    print_board(board)
    if turn==3:
        print "---------"
        print "The right Row:%s"%(ship_row)
        print "The right Col:%s"%(ship_col)
        board[ship_row-1][ship_col-1] = "R"
        print_board(board)
        print "Game Over"

 

7. Loops

　　for　　else

　　while　　else

 

　　break

　　enumerate(枚举)

 

 

　　Practice Makes Perfect

　　　　is_prime()(判断素数模型)(利用标记temp)

def is_prime(x):
    temp=True
    if x<2:
        temp=False
    elif x==2:
        temp=True
    else:
        i=2
        while i<x:
            if x%i==0:
                temp=False
            i+=1
    return temp