Python隨筆(一)、python基礎

在pycharm下設置本身的模板:

在File---settings---File and Code Templates---Python script 腳本里添加:

#!/usr/bin/env python 

#-*- coding:utf-8 _*-  

""" 

@author:${USER} 

@file: ${NAME}.py 

@time: ${YEAR}/${MONTH}/${DAY} 

"""  

1、第一個python程序：

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: HelloWorld.py
@time: 2017/11/{DAY} 
"""
print("HelloWorld!!!")
print("你好，世界")

2、變量和賦值：
#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: bianliang.py
@time: 2017/11/18 
"""
#賦值
name = "chenjisong"
age = 30
print(name,age)

字符串類型的必需要加引號

a = 3
b = a
a = 5
print(a,b)

返回結果爲(5,3)

解析：a = 3,內存地址指向3，b = a,則b = 3,此時a 和 b 都指向內存地址3，當 a = 5的時候，a 的內存地址指向了5，則a = 3 這個內存地址被回收了，可是b的內存地址未被回收，b仍然等於3，因此最後返回的結果是(5,3)

變量起名的原則：

      一、顯示，通俗易懂

      二、駝峯寫法（首字母大寫）          例如：NumsOfJackGf

      三、下橫線寫法（不能爲中橫線）   例如：nums_of_jack_gf

      四、不能數字開頭，可是能夠在中間和結尾

      五、命名中不能有特殊字符

      六、變量的命名不能有空格

     七、關鍵字不能聲明爲變量

 內存地址的驗證：

C:\Users\Administrator>python

Python 3.6.3 (v3.6.3:2c5fed8, Oct  3 2017, 18:11:49) [MSC v.1900 64 bit (AMD64)]

 on win32

Type "help", "copyright", "credits" or "license" for more information.

>>> import keyword

>>> a = 5

>>> b = a

>>> id(a),id(b)

(1363763552, 1363763552)

a 和 b的內存地址徹底同樣

>>> a = 10

>>> id(a),id(b)

>>> (1363763712, 1363763552)

當a的值改變以後，a的內存地址也發生了變化（是python中的內存地址，不是物理機器的內存地址）

3、用戶交互

[root@python3 ~]# python
Python 3.6.3 (default, Nov 12 2017, 04:07:16)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-16)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> name = input("please input your name:")
please input your name:chenjisong

>>> print(name)

chenjisong

>>> a = 5
>>> eval('a')
5

4、條件判斷與縮進

IF....ELSE和縮進

僞代碼：

若是   你是富二代

          咱們倆就拍拖

或者   你很努力上進

          咱們能夠接觸試試

不然

          免談

縮進要一致：
sex = input ("plsase input your gender:")
if sex == "gril":
    print("I would like to have a baby")
elif sex == "man":
    print("going to homesexual!")
else:
    print("Pervert!!!")

遊戲:猜幸運數字：

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: lucky_number.py
@time: 2017/11/18 
"""
lucky_number = 18
guess_number = int(input("can you guess my lucky_number:"))
if guess_number > lucky_number:
    print("guess_number is bigger then lucky_number")
elif guess_number < lucky_number:
    print("guess_number is smaller then lucky_number:")
else:
    print("congratulations,you guess it,but no prize")

5、循環控制:

break結束循環：（猜對即跳出循環，沒猜對就一直猜）

while True:   
    lucky_number = 18
    guess_number = int(input("can you guess my lucky_number:"))
    if guess_number > lucky_number:
        print("guess_number is bigger then lucky_number")
    elif guess_number < lucky_number:
        print("guess_number is smaller then lucky_number:")
    else:
        print("congratulations,you guess it,but no prize")
        break

while lucky_number != input_num:
    input_num = int(input("input the guess num:"))
    if input_num > lucky_number:
        print("the real number is smaller")
    elif input_num < lucky_number:
        print("the real number is bigger")
    else:
print("bingo")

6、循環次數限制：

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: lucky_number.py
@time: 2017/11/18 
"""
lucky_number = 18
input_num=-1
guess_count = 0
#while lucky_number != input_num:
while guess_count < 3:
    input_num = int(input("input the guess num:"))
    print("guess count:",guess_count)
    if input_num > lucky_number:
        print("the real number is smaller")
    elif input_num < lucky_number:
        print("the real number is bigger")
    else:
        print("Bingo!")
        break
    guess_count += 1
else:
    print("try too many times")

兩重判斷：

第一重：三次猜不對直接退出(guess_count>3)，打印「try too many times」

第二重：猜對了直接打印bingo,退出

for循環猜數字遊戲：

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: lucky_number.py
@time: 2017/11/18 
"""
#while True:
lucky_number = 18
input_num=-1

for i in range(5):
    input_num = int(input("input the guess num:"))
    if input_num > lucky_number:
        print("the real number is smaller")
    elif input_num < lucky_number:
        print("the real number is bigger")
    else:
        print("Bingo!")
        break
else:
    print("try too many times")

7、經常使用數據類型

數據類型：

數字：

     int(整型)

     float(浮點型)

     long(長整型)

布爾:(True(1) 和  False(0))  真和假

字符串    str

列表        list

元祖       tuple

字典       dict

type能夠查看數據類型：

>>> type(2**10)

<class 'int'>

>>> type(2.99)

<class 'float'>

8、字符串格式化

第一種寫法會開闢不少內存空間，對內存資源是一種浪費，因此不建議

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: string_format.py
@time: 2017/11/18 
"""
name = input("name:")
age = input("age：")
job = input("job:")

print("Information of "+ name +"\nName:" + name +"\nAge:"+ age +"\nJob:"+ job +"")

第二種寫法只開闢了一塊內存空間，能夠有效節省內存資源，效率更優

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: string_format.py
@time: 2017/11/18 
"""
name = input("name:")
age = input("age：")
job = input("job:")

print("Information of %s:\nName:%s\nAge:%s\nJob:%s" %(name,name,age,job))

%s要與後面的值一一對應，不然會報錯

第三種寫法：

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: string_format.py
@time: 2017/11/18 
"""
name = input("name:")
age = input("age：")
job = input("job:")
msg = '''
Information of %s:
     Name:%s
     Age :%s
     Job :%s
'''   %(name,name,age,job)
print(msg)

'''   

    '''的妙用

9、列表經常使用操做：

strip:去掉，拿掉空格：如下例子去掉了前面的空格，可是中間的無法去掉

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: string_format.py
@time: 2017/11/18 
"""
name = input("name:").strip()
age = input("age：").strip()
job = input("job:").strip()
msg = '''
Information of %s:
     Name:%s
     Age :%s
     Job :%s
'''   %(name,name,age,job)
print(msg)

輸入

name:          chen    jisong

age：     22

job:                 IT

輸出：

Information of chen    jisong:

     Name:chen    jisong

     Age :22

     Job :IT

也能夠去掉字符：以下

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: string_format.py
@time: 2017/11/18 
"""
name = input("name:").strip("chen")
age = input("age：").strip()
job = input("job:").strip()
msg = '''
Information of %s:
     Name:%s
     Age :%s
     Job :%s
'''   %(name,name,age,job)
print(msg)

輸入

name:           chen    jisong

age：     22

job:                 IT

輸出：

Information of jisong:

     Name:jisong

     Age :30

     Job :IT

列表索引(下標)取值:   []

[root@python3 ~]# python

Python 3.6.3 (default, Nov 12 2017, 04:07:16) 

[GCC 4.8.5 20150623 (Red Hat 4.8.5-16)] on linux

Type "help", "copyright", "credits" or "license" for more information.

>>> name_list = ["65brother","87brother","99brother"]

>>> name_list

['65brother', '87brother', '99brother']

>>> name_list[0]

'65brother'

>>> name_list[1]

'87brother'

>>> name_list[2]

'99brother'

>>> dir(name_list)

['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'append', 'clear', 'copy', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']

index        索引:

count       計數:

append    追加：

insert       插入：

pop          刪除最後一個索引值

remove    刪除固定的值

reverse     反轉

sort           排序

extend      列表的擴展

>>> name_list

['65brother', '87brother', '99brother']

>>> name_list.append("Eric")

>>> name_list

['65brother', '87brother', '99brother', 'Eric']

>>> name_list.append("87brother")

>>> name_list

['65brother', '87brother', '99brother', 'Eric', '87brother']

>>> name_list.index("87brother")

1

>>> name_list.count("87brother")

2

>>> name_list.insert(2,"66brother")      在索引2以後加66brother

>>> name_list

['65brother', '87brother', '66brother', '99brother', 'Eric', '87brother']

>>> name_list.remove("66brother")

>>> name_list

['65brother', '87brother', '99brother', 'Eric', '87brother']

>>> name_list.pop()                               

'87brother'

>>> name_list

['65brother', '87brother', '99brother', 'Eric']

>>> name_list.reverse()

>>> name_list

['Eric', '99brother', '87brother', '65brother']

>>> name_list.sort()

>>> name_list

['65brother', '87brother', '99brother', 'Eric']

>>> name_list.append("87brother")

>>> name_list.append("87brother")

>>> name_list

['65brother', '87brother', '99brother', 'Eric', '87brother', '87brother']

要一次刪除3個87brother，應當怎麼作？？？

>>> for i in range(name_list.count('87brother')):

...    name_list.remove("87brother")

... 

>>> name_list

['65brother', '99brother', 'Eric']

10、列表的後續操做

[root@python3 ~]# python

Python 3.6.3 (default, Nov 12 2017, 04:07:16) 

[GCC 4.8.5 20150623 (Red Hat 4.8.5-16)] on linux

Type "help", "copyright", "credits" or "license" for more information.

>>> a = [1, 2, 4, 3, 'a', 'b']

>>> a

[1, 2, 4, 3, 'a', 'b']

>>> a.insert(1,8)     ---在索引一處插入數字

>>> a

[1, 8, 2, 4, 3, 'a', 'b']

正向切片：

>>> a[3:5]

[4, 3]

>>> a[0:7]

[1, 8, 2, 4, 3, 'a', 'b']

反向切片：

>>> a[-4:]

[4, 3, 'a', 'b']

>>> a[-4:-1]

[4, 3, 'a']

>>> a[0:7]

[1, 8, 2, 4, 3, 'a', 'b']

>>> a.sort()

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

TypeError: '<' not supported between instances of 'str' and 'int'  字符串和整型不能進行排序

>>> a[0:7]

[1, 2, 3, 4, 8, 'a', 'b']

>>> a.pop()

'b'

>>> a.pop()

'a'

>>> a.sort()

>>> a

[1, 2, 3, 4, 8]

拿掉字符串後便可進行排序

列表能夠相加：

>>> a = [1,2,3,4,5,6,7,8,9]

>>> b = ["a","b","c","d","e","f","g","h","i"]

>>> a + b

[1, 2, 3, 4, 5, 6, 7, 8, 9, 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i']

>>> a.extend(b)

>>> a

[1, 2, 3, 4, 5, 6, 7, 8, 9, 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i']

11、二進制位運算

元祖：

>>> t = (1,2,3,4)

>>> dir(t)

['__add__', '__class__', '__contains__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'count', 'index']

元祖改列表，用list方法：

>>> type(t)

<class 'tuple'>

>>> list(t)

[1, 2, 3, 4]

>>> type(t)

<class 'tuple'>

>>> a = list(t)

>>> type(a)

<class 'list'>

二進制運算：

>>> A = 10

>>> B = 50

>>> A & B              二者都真才爲真

2

>>> A | B                二者有一真就爲真

58

>>> A ^ B              一真一假則爲真

56

>>> A >> 1            總體往右移一位

5

>>> A << 1            總體往左移一位

20

>>> B >> 1

25

>>> B << 1

100

邏輯運算符：與(and)  或(or)  非(not)

>>> sex = "man"

>>> age = 26

>>> if sex == "man" and age > 25:

...    print("time to get married")

... 

time to get married

>>> sex = "man"

>>> age = 26

>>> if sex == "man" or age < 23:

...     print("do not worried")

... 

do not worried

>>> name_list=["oldboy","alex","eric"]

>>> if "jack" not in name_list:

...      print("sorry")

... 

sorry

身份運算符(is    is not)

>>> name_list=["oldboy","alex","eric"]

>>> type(name_list) is tuple

False

>>> type(name_list) is list

True

>>> type(name_list) is not list

False

>>> type(name_list) is not tuple

True

12、簡單的嵌套循環

continue  跳出本次循環，繼續下一次循環：

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: cotinue.py
@time: 2017/11/19 
"""  
for i in range(10):
    if i < 5:
        continue
    print(i)

執行結果以下：

E:\Python36\python.exe C:/Users/Administrator/PycharmProjects/S12/2017-11-18/cotinue.py

5

6

7

8

9

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: cotinue.py
@time: 2017/11/19 
"""
for j in range(5):
    for i in range(10):
        if i < 5:
            continue
        if j> 3:
            break
        print(i)

執行結果：

5

6

7

8

9

5

6

7

8

9

5

6

7

8

9

5

6

7

8

9

十3、文件的基本操做

讀取文件的內容：

一次性加載全部內容到內存

obj.read()

一次性加載全部內容到內存，並根據行分割成字符串

obj.readlines()

每次僅讀取一行數據：

for line in obj:

     print line

寫入文件內容：

obj.write(「內容」)

關閉文件句柄：

obj.close()

打開文件：

file_obj = file("文件路徑","模式")

file_obj = open("文件路徑","模式")

打開文件的模式有：

r          以只讀方式打開文件。

w         打開一個文件只用於寫入。

a          打開一個文件用於追加。

w+       打開一個文件用於讀寫。

寫文件的操做：

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: file_opr.py
@time: 2017/11/19 
"""
f = open("test.log","w")
f.write("this is the first line\n")
f.write("this is the second line\n")
f.write("this is the third line\n")
f.write("this is the fourth line\n")
f.close()

test.log下面的文字：

this is the first line
this is the second line
this is the third line
this is the fourth line

讀文件的操做，循環逐行讀取：

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: file_opr.py
@time: 2017/11/19 
"""
f = open("test.log","r")
#f.write("this is the first line\n")
#f.write("this is the second line\n")
#f.write("this is the third line\n")
#f.write("this is the fourth line\n")
for line in f:
    print (line)，
f.close()

執行結果：

this is the first line

this is the second line

this is the third line

this is the fourth line

判斷：

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: file_opr.py
@time: 2017/11/19 
"""
f = open("test.log","r")
#f.write("this is the first line\n")
#f.write("this is the second line\n")
#f.write("this is the third line\n")
#f.write("this is the fourth line\n")
for line in f:
   if "third" in line:
       print ("this is 3 line")
   else:
       print(line)
f.close()

追加文件操做:

#!usr/bin/env python 
#-*- coding:utf-8 _*-  
""" 
@author:Administrator 
@file: file_opr.py
@time: 2017/11/19 
"""
f = open("test.log","a")
#f.write("this is the first line\n")
#f.write("this is the second line\n")
#f.write("this is the third line\n")
#f.write("this is the fourth line\n")
#for line in f:
#   if "third" in line:
#       print ("this is 3 line")
#   else:
#       print(line)
f.write("8\n")
f.write("9\n")
f.write("5\n")
f.write("6\n")
f.write("7\n")
f.close()

test.log輸出結果：

this is the first line
this is the second line
this is the third line
this is the fourth line
8
9
5
6
7