Python-2 Python之路,Day2 - Python基礎2

阿新 • • 發佈：2022-04-13

Python之路,Day2 - Python基礎2

2. 字串操作　　

檢視程式碼

name.capitalize()  首字母大寫
name.casefold()   大寫全部變小寫
name.center(50,"-")  輸出 '---------------------Alex Li----------------------'
name.count('lex') 統計 lex出現次數
name.encode()  將字串編碼成bytes格式
name.endswith("Li")  判斷字串是否以 Li結尾
 "Alex\tLi".expandtabs(10) 輸出'Alex      Li'， 將\t轉換成多長的空格 
 name.find('A')  查詢A,找到返回其索引， 找不到返回-1 

format :
    >>> msg = "my name is {}, and age is {}"
    >>> msg.format("alex",22)
    'my name is alex, and age is 22'
    >>> msg = "my name is {1}, and age is {0}"
    >>> msg.format("alex",22)
    'my name is 22, and age is alex'
    >>> msg = "my name is {name}, and age is {age}"
    >>> msg.format(age=22,name="ale")
    'my name is ale, and age is 22'
format_map
    >>> msg.format_map({'name':'alex','age':22})
    'my name is alex, and age is 22'


msg.index('a')  返回a所在字串的索引
'9aA'.isalnum()   True

'9'.isdigit() 是否整數
name.isnumeric  
name.isprintable
name.isspace
name.istitle
name.isupper
 "|".join(['alex','jack','rain'])
'alex|jack|rain'


maketrans
    >>> intab = "aeiou"  #This is the string having actual characters. 
    >>> outtab = "12345" #This is the string having corresponding mapping character
    >>> trantab = str.maketrans(intab, outtab)
    >>> 
    >>> str = "this is string example....wow!!!"
    >>> str.translate(trantab)
    'th3s 3s str3ng 2x1mpl2....w4w!!!'

 msg.partition('is')   輸出 ('my name ', 'is', ' {name}, and age is {age}') 

 >>> "alex li, chinese name is lijie".replace("li","LI",1)
     'alex LI, chinese name is lijie'

 msg.swapcase 大小寫互換


 >>> msg.zfill(40)
'00000my name is {name}, and age is {age}'



>>> n4.ljust(40,"-")
'Hello 2orld-----------------------------'
>>> n4.rjust(40,"-")
'-----------------------------Hello 2orld'


>>> b="ddefdsdff_哈哈" 
>>> b.isidentifier() #檢測一段字串可否被當作標誌符，即是否符合變數命名規則
True

3. 字典操作

字典一種key - value 的資料型別，使用就像我們上學用的字典，通過筆劃、字母來查對應頁的詳細內容。

語法:

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info = {
    'stu1101': "TengLan Wu",
    'stu1102': "LongZe Luola",
    'stu1103': "XiaoZe Maliya",
}

字典的特性：

dict是無序的
key必須是唯一的,so 天生去重

增加

檢視程式碼

>>> info["stu1104"] = "蒼井空"
>>> info
{'stu1102': 'LongZe Luola', 'stu1104': '蒼井空', 'stu1103': 'XiaoZe Maliya', 'stu1101': 'TengLan Wu'}

修改

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>>> info['stu1101'] = "武藤蘭"
>>> info
{'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya', 'stu1101': '武藤蘭'}

刪除

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>>> info
{'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya', 'stu1101': '武藤蘭'}
>>> info.pop("stu1101") #標準刪除姿勢
'武藤蘭'
>>> info
{'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya'}
>>> del info['stu1103'] #換個姿勢刪除
>>> info
{'stu1102': 'LongZe Luola'}
>>> 
>>> 
>>> 
>>> info = {'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya'}
>>> info
{'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya'} #隨機刪除
>>> info.popitem()
('stu1102', 'LongZe Luola')
>>> info
{'stu1103': 'XiaoZe Maliya'}

查詢

檢視程式碼

>>> info
{'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya', 'stu1101': '武藤蘭'}
>>> info.pop("stu1101") #標準刪除姿勢
'武藤蘭'
>>> info
{'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya'}
>>> del info['stu1103'] #換個姿勢刪除
>>> info
{'stu1102': 'LongZe Luola'}
>>> 
>>> 
>>> 
>>> info = {'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya'}
>>> info
{'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya'} #隨機刪除
>>> info.popitem()
('stu1102', 'LongZe Luola')
>>> info
{'stu1103': 'XiaoZe Maliya'}

查詢

檢視程式碼

>>> info = {'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya'}
>>> 
>>> "stu1102" in info #標準用法
True
>>> info.get("stu1102")  #獲取
'LongZe Luola'
>>> info["stu1102"] #同上，但是看下面
'LongZe Luola'
>>> info["stu1105"]  #如果一個key不存在，就報錯，get不會，不存在只返回None
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
KeyError: 'stu1105'

多級字典巢狀及操作

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av_catalog = {
    "歐美":{
        "www.youpor.com": ["很多免費的,世界最大的","質量一般"],
        "www.pornhub.com": ["很多免費的,也很大","質量比yourporn高點"],
        "letmedothistoyou.com": ["多是自拍,高質量圖片很多","資源不多,更新慢"],
        "x-art.com":["質量很高,真的很高","全部收費,屌比請繞過"]
    },
    "日韓":{
        "tokyo-hot":["質量怎樣不清楚,個人已經不喜歡日韓範了","聽說是收費的"]
    },
    "大陸":{
        "1024":["全部免費,真好,好人一生平安","伺服器在國外,慢"]
    }
}

av_catalog["大陸"]["1024"][1] += ",可以用爬蟲爬下來"
print(av_catalog["大陸"]["1024"])
#ouput 
['全部免費,真好,好人一生平安', '伺服器在國外,慢,可以用爬蟲爬下來']

其它姿勢

檢視程式碼

#values
>>> info.values()
dict_values(['LongZe Luola', 'XiaoZe Maliya'])

#keys
>>> info.keys()
dict_keys(['stu1102', 'stu1103'])


#setdefault
>>> info.setdefault("stu1106","Alex")
'Alex'
>>> info
{'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya', 'stu1106': 'Alex'}
>>> info.setdefault("stu1102","龍澤蘿拉")
'LongZe Luola'
>>> info
{'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya', 'stu1106': 'Alex'}


#update 
>>> info
{'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya', 'stu1106': 'Alex'}
>>> b = {1:2,3:4, "stu1102":"龍澤蘿拉"}
>>> info.update(b)
>>> info
{'stu1102': '龍澤蘿拉', 1: 2, 3: 4, 'stu1103': 'XiaoZe Maliya', 'stu1106': 'Alex'}

#items
info.items()
dict_items([('stu1102', '龍澤蘿拉'), (1, 2), (3, 4), ('stu1103', 'XiaoZe Maliya'), ('stu1106', 'Alex')])


#通過一個列表生成預設dict,有個沒辦法解釋的坑，少用吧這個
>>> dict.fromkeys([1,2,3],'testd')
{1: 'testd', 2: 'testd', 3: 'testd'}

迴圈dict

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#方法1
for key in info:
    print(key,info[key])

#方法2
for k,v in info.items(): #會先把dict轉成list,資料裡大時莫用
    print(k,v)

程式練習

程式: 三級選單

要求:

列印省、市、縣三級選單
可返回上一級
可隨時退出程式

檢視程式碼

menu = {
    '北京':{
        '海淀':{
            '五道口':{
                'soho':{},
                '網易':{},
                'google':{}
            },
            '中關村':{
                '愛奇藝':{},
                '汽車之家':{},
                'youku':{},
            },
            '上地':{
                '百度':{},
            },
        },
        '昌平':{
            '沙河':{
                '老男孩':{},
                '北航':{},
            },
            '天通苑':{},
            '回龍觀':{},
        },
        '朝陽':{},
        '東城':{},
    },
    '上海':{
        '閔行':{
            "人民廣場":{
                '炸雞店':{}
            }
        },
        '閘北':{
            '火車戰':{
                '攜程':{}
            }
        },
        '浦東':{},
    },
    '山東':{},
}


exit_flag = False
current_layer = menu

layers = [menu]

while not  exit_flag:
    for k in current_layer:
        print(k)
    choice = input(">>:").strip()
    if choice == "b":
        current_layer = layers[-1]
        #print("change to laster", current_layer)
        layers.pop()
    elif choice not  in current_layer:continue
    else:
        layers.append(current_layer)
        current_layer = current_layer[choice]
三年選單文藝青年版

4.集合操作

集合是一個無序的，不重複的資料組合，它的主要作用如下：

去重，把一個列表變成集合，就自動去重了
關係測試，測試兩組資料之前的交集、差集、並集等關係

常用操作

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s = set([3,5,9,10])      #建立一個數值集合  
  
t = set("Hello")         #建立一個唯一字元的集合  


a = t | s          # t 和 s的並集  
  
b = t & s          # t 和 s的交集  
  
c = t – s          # 求差集（項在t中，但不在s中）  
  
d = t ^ s          # 對稱差集（項在t或s中，但不會同時出現在二者中）  
  
   
  
基本操作：  
  
t.add('x')            # 新增一項  
  
s.update([10,37,42])  # 在s中新增多項  
  
   
  
使用remove()可以刪除一項：  
  
t.remove('H')  
  
  
len(s)  
set 的長度  
  
x in s  
測試 x 是否是 s 的成員  
  
x not in s  
測試 x 是否不是 s 的成員  
  
s.issubset(t)  
s <= t  
測試是否 s 中的每一個元素都在 t 中  
  
s.issuperset(t)  
s >= t  
測試是否 t 中的每一個元素都在 s 中  
  
s.union(t)  
s | t  
返回一個新的 set 包含 s 和 t 中的每一個元素  
  
s.intersection(t)  
s & t  
返回一個新的 set 包含 s 和 t 中的公共元素  
  
s.difference(t)  
s - t  
返回一個新的 set 包含 s 中有但是 t 中沒有的元素  
  
s.symmetric_difference(t)  
s ^ t  
返回一個新的 set 包含 s 和 t 中不重複的元素  
  
s.copy()  
返回 set “s”的一個淺複製

5. 檔案操作

對檔案操作流程

開啟檔案，得到檔案控制代碼並賦值給一個變數
通過控制代碼對檔案進行操作
關閉檔案

現有檔案如下

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 Somehow, it seems the love I knew was always the most destructive kind 不知為何，我經歷的愛情總是最具毀滅性的的那種 Yesterday when I was young 昨日當我年少輕狂 The taste of life was sweet 生命的滋味是甜的 As rain upon my tongue 就如舌尖上的雨露 I teased at life as if it were a foolish game 我戲弄生命視其為愚蠢的遊戲 The way the evening breeze 就如夜晚的微風 May tease the candle flame 逗弄蠟燭的火苗 The thousand dreams I dreamed 我曾千萬次夢見 The splendid things I planned 那些我計劃的絢麗藍圖 I always built to last on weak and shifting sand 但我總是將之建築在易逝的流沙上 I lived by night and shunned the naked light of day 我夜夜笙歌逃避白晝赤裸的陽光 And only now I see how the time ran away 事到如今我才看清歲月是如何匆匆流逝 Yesterday when I was young 昨日當我年少輕狂 So many lovely songs were waiting to be sung 有那麼多甜美的曲兒等我歌唱 So many wild pleasures lay in store for me 有那麼多肆意的快樂等我享受 And so much pain my eyes refused to see 還有那麼多痛苦我的雙眼卻視而不見 I ran so fast that time and youth at last ran out 我飛快地奔走最終時光與青春消逝殆盡 I never stopped to think what life was all about 我從未停下腳步去思考生命的意義 And every conversation that I can now recall 如今回想起的所有對話 Concerned itself with me and nothing else at all 除了和我相關的什麼都記不得了 The game of love I played with arrogance and pride 我用自負和傲慢玩著愛情的遊戲 And every flame I lit too quickly, quickly died 所有我點燃的火焰都熄滅得太快 The friends I made all somehow seemed to slip away 所有我交的朋友似乎都不知不覺地離開了 And only now I'm left alone to end the play, yeah 只剩我一個人在臺上來結束這場鬧劇 Oh, yesterday when I was young 噢昨日當我年少輕狂 So many, many songs were waiting to be sung 有那麼那麼多甜美的曲兒等我歌唱 So many wild pleasures lay in store for me 有那麼多肆意的快樂等我享受 And so much pain my eyes refused to see 還有那麼多痛苦我的雙眼卻視而不見 There are so many songs in me that won't be sung 我有太多歌曲永遠不會被唱起 I feel the bitter taste of tears upon my tongue 我嚐到了舌尖淚水的苦澀滋味 The time has come for me to pay for yesterday 終於到了付出代價的時間為了昨日 When I was young 當我年少輕狂

基本操作　　

1 2 3 4 5 6 7 8 f = open('lyrics') #開啟檔案 first_line = f.readline() print('first line:',first_line) #讀一行 print('我是分隔線'.center(50,'-')) data = f.read()# 讀取剩下的所有內容,檔案大時不要用 print(data) #列印檔案 f.close() #關閉檔案

開啟檔案的模式有：

r，只讀模式（預設）。
w，只寫模式。【不可讀；不存在則建立；存在則刪除內容；】
a，追加模式。【可讀；不存在則建立；存在則只追加內容；】

"+" 表示可以同時讀寫某個檔案

r+，可讀寫檔案。【可讀；可寫；可追加】
w+，寫讀
a+，同a

"U"表示在讀取時，可以將 \r \n \r\n自動轉換成 \n （與 r 或 r+ 模式同使用）

"b"表示處理二進位制檔案（如：FTP傳送上傳ISO映象檔案，linux可忽略，windows處理二進位制檔案時需標註）

其它語法

檢視程式碼

def close(self): # real signature unknown; restored from __doc__
        """
        Close the file.
        
        A closed file cannot be used for further I/O operations.  close() may be
        called more than once without error.
        """
        pass

    def fileno(self, *args, **kwargs): # real signature unknown
        """ Return the underlying file descriptor (an integer). """
        pass

    def isatty(self, *args, **kwargs): # real signature unknown
        """ True if the file is connected to a TTY device. """
        pass

    def read(self, size=-1): # known case of _io.FileIO.read
        """
        注意，不一定能全讀回來
        Read at most size bytes, returned as bytes.
        
        Only makes one system call, so less data may be returned than requested.
        In non-blocking mode, returns None if no data is available.
        Return an empty bytes object at EOF.
        """
        return ""

    def readable(self, *args, **kwargs): # real signature unknown
        """ True if file was opened in a read mode. """
        pass

    def readall(self, *args, **kwargs): # real signature unknown
        """
        Read all data from the file, returned as bytes.
        
        In non-blocking mode, returns as much as is immediately available,
        or None if no data is available.  Return an empty bytes object at EOF.
        """
        pass

    def readinto(self): # real signature unknown; restored from __doc__
        """ Same as RawIOBase.readinto(). """
        pass #不要用,沒人知道它是幹嘛用的

    def seek(self, *args, **kwargs): # real signature unknown
        """
        Move to new file position and return the file position.
        
        Argument offset is a byte count.  Optional argument whence defaults to
        SEEK_SET or 0 (offset from start of file, offset should be >= 0); other values
        are SEEK_CUR or 1 (move relative to current position, positive or negative),
        and SEEK_END or 2 (move relative to end of file, usually negative, although
        many platforms allow seeking beyond the end of a file).
        
        Note that not all file objects are seekable.
        """
        pass

    def seekable(self, *args, **kwargs): # real signature unknown
        """ True if file supports random-access. """
        pass

    def tell(self, *args, **kwargs): # real signature unknown
        """
        Current file position.
        
        Can raise OSError for non seekable files.
        """
        pass

    def truncate(self, *args, **kwargs): # real signature unknown
        """
        Truncate the file to at most size bytes and return the truncated size.
        
        Size defaults to the current file position, as returned by tell().
        The current file position is changed to the value of size.
        """
        pass

    def writable(self, *args, **kwargs): # real signature unknown
        """ True if file was opened in a write mode. """
        pass

    def write(self, *args, **kwargs): # real signature unknown
        """
        Write bytes b to file, return number written.
        
        Only makes one system call, so not all of the data may be written.
        The number of bytes actually written is returned.  In non-blocking mode,
        returns None if the write would block.
        """
        pass

with語句

為了避免開啟檔案後忘記關閉，可以通過管理上下文，即：

1 2 3 with open('log','r') as f: ...

如此方式，當with程式碼塊執行完畢時，內部會自動關閉並釋放檔案資源。

在Python 2.7 後，with又支援同時對多個檔案的上下文進行管理，即：

1 2	`with` `open('log1') as obj1,` `open('log2') as obj2:` `pass`

程式練習　　

程式1: 實現簡單的shell sed替換功能

程式2:修改haproxy配置檔案

需求：

檢視程式碼

1、查
    輸入：www.oldboy.org
    獲取當前backend下的所有記錄

2、新建
    輸入：
        arg = {
            'bakend': 'www.oldboy.org',
            'record':{
                'server': '100.1.7.9',
                'weight': 20,
                'maxconn': 30
            }
        }

3、刪除
    輸入：
        arg = {
            'bakend': 'www.oldboy.org',
            'record':{
                'server': '100.1.7.9',
                'weight': 20,
                'maxconn': 30
            }
        }
需求

原始碼

global       
        log 127.0.0.1 local2
        daemon
        maxconn 256
        log 127.0.0.1 local2 info
defaults
        log global
        mode http
        timeout connect 5000ms
        timeout client 50000ms
        timeout server 50000ms
        option  dontlognull

listen stats :8888
        stats enable
        stats uri       /admin
        stats auth      admin:1234

frontend oldboy.org
        bind 0.0.0.0:80
        option httplog
        option httpclose
        option  forwardfor
        log global
        acl www hdr_reg(host) -i www.oldboy.org
        use_backend www.oldboy.org if www

backend www.oldboy.org
        server 100.1.7.9 100.1.7.9 weight 20 maxconn 3000
原配置檔案

6. 字元編碼與轉碼

詳細文章:

http://www.cnblogs.com/yuanchenqi/articles/5956943.html

http://www.diveintopython3.net/strings.html

需知:

1.在python2預設編碼是ASCII, python3裡預設是unicode

2.unicode 分為 utf-32(佔4個位元組),utf-16(佔兩個位元組)，utf-8(佔1-4個位元組)， so utf-16就是現在最常用的unicode版本，不過在檔案裡存的還是utf-8，因為utf8省空間

3.在py3中encode,在轉碼的同時還會把string 變成bytes型別，decode在解碼的同時還會把bytes變回string

上圖僅適用於py2
in python2
#-*-coding:utf-8-*-
__author__ = 'Alex Li'

import sys
print(sys.getdefaultencoding())


msg = "我愛北京天安門"
msg_gb2312 = msg.decode("utf-8").encode("gb2312")
gb2312_to_gbk = msg_gb2312.decode("gbk").encode("gbk")

print(msg)
print(msg_gb2312)
print(gb2312_to_gbk)
in python2
in python3
#-*-coding:gb2312 -*-   #這個也可以去掉
__author__ = 'Alex Li'

import sys
print(sys.getdefaultencoding())


msg = "我愛北京天安門"
#msg_gb2312 = msg.decode("utf-8").encode("gb2312")
msg_gb2312 = msg.encode("gb2312") #預設就是unicode,不用再decode,喜大普奔
gb2312_to_unicode = msg_gb2312.decode("gb2312")
gb2312_to_utf8 = msg_gb2312.decode("gb2312").encode("utf-8")

print(msg)
print(msg_gb2312)
print(gb2312_to_unicode)
print(gb2312_to_utf8)
in python3

Python-2 Python之路,Day2 - Python基礎2

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