Python基础（一）

1.起步

搭建编程环境
Linux、OS X、Windows
（Windows系统下载Python2或Python3 + Pycharm）

>>>print("Hello!")

有C++基础学Pyhon基础语法很轻松啦，哈哈

Python2和Python3语法差别不大

Python需要注意缩进

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2.变量 简单数据类型

变量、字符串、数字、注释

name.py

first_name = "ada"
last_name = "lovelace"
full_name = first_name + " " + last_name

message = "Hello, " + full_name.title() + "!"
print(message)
# Say hello to everyone.
print("Hello Python people!")

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3.列表

（类似数组）索引从0开始
但可直接使用的函数很多，操作简单快捷。
字符串列表、数值列表
示例

motorcycles = ['honda', 'yamaha', 'suzuki', 'ducati'] 
print(motorcycles)

too_expensive = 'ducati'
motorcycles.remove(too_expensive)
print(motorcycles)
print("\nA " + too_expensive.title() + " is too expensive for me.")

修改列表元素

a[0]='haha'

添加元素

a.append('haha') #列表末尾
a.insert(0,'haha')#列表中

删除元素

del a[0]
a.pop() #删除末尾
a.pop(0)
a.remove('haha')#根据值删除元素

操作列表

a.sort()#永久性排序
a.sorted()#临时排序
a.reverse()
len(a)

for循环遍历

magicians = ['alice', 'david', 'carolina'] 
for magician in magicians: 
    print(magician.title() + ", that was a great trick!")  

range()创建数值列表

numbers = list(range(1,6)) 
print(numbers) 
min(numbers) #方便的函数
max(numbers)
sum(numbers)

切片

players = ['charles', 'martina', 'michael', 'florence', 'eli'] 
for player in players[:3]:
    print(player.title())

b=a[:]#复制列表

元组（不可变的列表）

dimensions = (200, 50)
print("Original dimensions:")
for dimension in dimensions:
    print(dimension)

dimensions = (400, 100)
print("\nModified dimensions:")
for dimension in dimensions:
    print(dimension)

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4.字典

示例

alien_0 = {'x_position': 0, 'y_position': 25, 'speed': 'medium'}
print("Original position: " + str(alien_0['x_position']))

# Move the alien to the right.
# Figure out how far to move the alien based on its speed.
if alien_0['speed'] == 'slow':
    x_increment = 1
elif alien_0['speed'] == 'medium':
    x_increment = 2
else:
    # This must be a fast alien.
    x_increment = 3

# The new position is the old position plus the increment.
alien_0['x_position'] = alien_0['x_position'] + x_increment

print("New position: " + str(alien_0['x_position']))

del a['haha']##删除



user_0 = {'username': 'efermi',  ##遍历
          'first': 'enrico',
          'last': 'fermi',
          }
for key, value in user_0.items():
    print("\nKey: " + key)
    print("Value: " + value)

avorite_languages = {
    'jen': 'python',
    'sarah': 'c',
    'edward': 'ruby',
    'phil': 'python',
    }

for name, language in favorite_languages.items():
    print(name.title() + "'s favorite language is " +
        language.title() + ".")

嵌套
存储字典的列表
存储列表的字典
存储字典的字典

users = {'aeinstein': {'first': 'albert',
                       'last': 'einstein',
                       'location': 'princeton'},
         'mcurie': {'first': 'marie',
                    'last': 'curie',
                    'location': 'paris'},
         }

for username, user_info in users.items():
    print("\nUsername: " + username)
    full_name = user_info['first'] + " " + user_info['last']
    location = user_info['location']

    print("\tFull name: " + full_name.title())
    print("\tLocation: " + location.title())