Head First Python 学习笔记（第一章：使用IDLE来帮助学习Python）

使用IDLE来帮助学习Python

Python程序员通常把内置函数称为BIF，print() BIF的作用是吧消息显示到标准输出（通常是屏幕）

print("You can experiment with code within IDEL's shell Coool, eh?")
if 43>42
        print("Don't panic!")

 有效地使用IDEL

• TAB完成：自动完成语句
• 回退代码语句：Win/Linux下使用ALT+P/N，Mac下使用Control+P/N
• 编辑回退语句
• 调整IDLE的首选项

创建简单的Python列表

要遵循的四个步骤：

• 在数据两边加引号
• 用都好将列表项与下一项隔开
• 再列表的两边加上开始和结束的中括号
• 使用赋值操作（=）将这个列表赋至一个标示符

Python的变量标识符没有类型

movies =["The Holy Grail","The Life of Brian","The meaning of Life" ]

列表就像是数组

使用中括号记法访问列表数据

print(movies[1])

可使用print（） BIF再屏幕上显示一个列表，使用len()BIF得出列表中有多少个数据项

>>> cast =["Cleese",'Palin','Jones',"Idle"]
>>> print(cast)
['Cleese', 'Palin', 'Jones', 'Idle']
>>> print(len(cast))
4
>>> print(cast[1])
Palin

再列表末尾增加一个数据项使用方法append()，从列表末尾删除数据使用方法(pop())，在列表末尾增加一个数据项集合extend(); 

>>> cast.append("Gilliam")
>>> print(cast)
['Cleese', 'Palin', 'Jones', 'Idle', 'Gilliam']
>>> cast.pop()
'Gilliam'
>>> print(cast)
['Cleese', 'Palin', 'Jones', 'Idle']
>>> cast.extend(["Gilliam","Chapman"])
>>> print(cast)
['Cleese', 'Palin', 'Jones', 'Idle', 'Gilliam', 'Chapman']

删除特定的数据项，在某些特定的位置插入一个元素

>>> cast.remove("Chapman")
>>> print(cast)
['Cleese', 'Palin', 'Jones', 'Idle', 'Gilliam']
>>> cast.insert(0,"Chapman")
>>> print(cast)
['Chapman', 'Cleese', 'Palin', 'Jones', 'Idle', 'Gilliam']

向列表增加更多数据

在之前的movies每一项前增加时间

代码一：

>>> movies.insert(1,1975)
>>> movies.insert(3,1979)
>>> movies.append(1983)
>>> print(movies)
['The Holy Grail', 1975, 'The Life of Brian', 1979, 'The meaning of Life', 1983]

方法二：

>>> movies=['The Holy Grail', 1975, 'The Life of Brian', 1979, 'The meaning of Life', 1983]
>>> print(movies)
['The Holy Grail', 1975, 'The Life of Brian', 1979, 'The meaning of Life', 1983]

处理列表数据

for迭代处理数据

>>> for each_flick in fav_movies:
        print(each_flick) """注意前面有TAB"""

        
The Holy Grail
The Life of Brian

For循环处理任意大小的列表

while和for的对比

while:

>>> count=0
>>> while count<len(movies):
        print(movies[count])
        count=count+1

        
The Holy Grail
1975
The Life of Brian
1979
The meaning of Life
1983

for:

>>> for each_item in movies:
        print(each_item)

        
The Holy Grail
1975
The Life of Brian
1979
The meaning of Life
1983

在列表中存储列表

列表可以存放混合类型的数据，也包含任何列表

movies=['The Holy Grail', 1975, "Terry Jones & Terry Gilliam",91,["Graham Chapman",["Michael Palin","John Cleese","Terry Gilliam","Eric Idle","Terry Jones"]]]
print(movies[4][1][3])

用for循环来处理这个列表

>>> movies=['The Holy Grail', 1975, "Terry Jones & Terry Gilliam",91,["Graham Chapman",["Michael Palin","John Cleese","Terry Gilliam","Eric Idle","Terry Jones"]]]
>>> print(movies[4][1][3])
Eric Idle
>>> print(movies)
['The Holy Grail', 1975, 'Terry Jones & Terry Gilliam', 91, ['Graham Chapman', ['Michael Palin', 'John Cleese', 'Terry Gilliam', 'Eric Idle', 'Terry Jones']]]
>>> for each_item in movies:
        print(each_item)

        
The Holy Grail
1975
Terry Jones & Terry Gilliam
91
['Graham Chapman', ['Michael Palin', 'John Cleese', 'Terry Gilliam', 'Eric Idle', 'Terry Jones']]

在列表中查找列表

isinstance() 用来判断当前处理的数据是不是某类型

for each_item in movies:
        if isinstance(each_item,list):
            for nested_item in each_item:
                    if isinstance(nested_item,list):
                        for deeper_item in nested_item:
                                print(deeper_item)
                    else:
                        print(nested_item)

        else:
            print(each_item)

            
The Holy Grail
1975
Terry Jones & Terry Gilliam
91
Graham Chapman
Michael Palin
John Cleese
Terry Gilliam
Eric Idle
Terry Jones

在Python中创建一个函数

def 函数名（参数）：

　　函数代码组

>>> def print_lol(the_list):
        for each_item in the_list:
                if isinstance(each_item,list):
                        print_lol(each_item)
                else:
                    print(each_item)

                    
>>> print_lol(movies)
The Holy Grail
1975
Terry Jones & Terry Gilliam
91
Graham Chapman
Michael Palin
John Cleese
Terry Gilliam
Eric Idle
Terry Jones