簡明python教程讀書記錄

@author : istory85

第九章 數據結構

1.字符串的方法

name = 'Swaroop'
if name.startswith('Swa'):
    print 'Yes, the string starts with "Swa"'
if 'a' in name:
    print 'Yes, it contains the string "a"'
if name.find('war') != -1:
    print 'Yes, it contains war'
delimiter = '_*_'
mylist = ['Brazil', 'Russia', 'Japan', 'China']
print delimiter.join(mylist)

第十章 編寫一個python腳本

1. 備份腳本 版本4.0

import os
import time
source = ['/root/a.txt', '/root/b.txt']
target_dir = '/root/backup/'
today = target_dir + time.strftime('%Y%m%d')
now = time.strftime('%H%M%S')
comment = raw_input('Enter a comment --> ')
if len(comment)== 0:
    target = today + os.sep + now + '.zip'
else:
    target = today + os.sep + now + '_' + \
             comment.replace(' ', '_') + '.zip'
if not os.path.exists(today):
    os.mkdir(today)
    print 'Successfully created directory', today
zip_command = "zip -qr '%s' %s" %(target, ' '.join(source))
if os.system(zip_command) == 0:
    print 'Successful backup to', target
else:
    print 'Backup Failed'

第十一章 面向對象的編程

1.定義一個簡單的人 類

class Person:
    def __init__(self, name):
        self.name = name
    def sayHi(self):
        print 'Hello, my name is', self.name
p = Person('Swaroop')
p.sayHi()

2.測試一個類

class Person:
    population = 0
    def __init__(self, name):
        self.name = name
        print '(Initializing %s)' % self.name
        Person.population += 1
    def __del__(self):
        print '%s says bye.' % self.name
        Person.population -= 1
        if Person.population == 0:
            print 'I am the last one.'
        else:
            print 'there are still %d people left.' % Person.population
    def sayHi(self):
        print 'Hi, my name is %s.' % self.name
    def howMany(self):
        if Person.population == 1:
            print 'I am the only person here.'
        else:
            print 'We have %d persons here.' % Person.population
swaroop = Person('Swaroop')
swaroop.sayHi()
swaroop.howMany()
kalam = Person('Abdul Kalam')
kalam.sayHi()
kalam.howMany()
swaroop.sayHi()
swaroop.howMany()
kalam.__del__()
kalam.howMany()
swaroop.__del__()
swaroop.howMany()

3.繼承 ,由學校成員類繼承出老師類和學生類

class SchoolMember:
    def __init__(self, name, age):
        self.name = name
        self.age = age
        print '(Initialized SchoolMemeber: %s)' % self.name
    def tell(self):
        print 'Name:"%s" Age:"%s"' % (self.name, self.age)
class Teacher(SchoolMember):
    def __init__(self, name, age, salary):
        SchoolMember.__init__(self, name, age)
        self.salary = salary
        print '(Initialized Teacher: %s)' % self.name
    def tell(self):
        SchoolMember.tell(self)
        print 'Salary: "%d"' % self.salary

class Student(SchoolMember):
    def __init__(self, name, age, marks):
        SchoolMember.__init__(self, name, age)
        self.marks = marks
        print '(Initialized Student: %s)' % self.name
    def tell(self):
        SchoolMember.tell(self)
        print 'Marks: "%d"' % self.marks
t = Teacher('Mrs. Shrividya', 40, 3000)
s = Student('Swaroop', 22, 75)
print   #prints a blank line
members = [t, s]
for member in members:
    member.tell()

第十二章 文件的輸入，輸出

1.一首簡單小詩歌的打印

poem = '''\
Programing is fun
when the work is done
if you wanna makeyour work also fun:
        use Python!
'''
f = file('poem.txt', 'w')
f.write(poem)
f.close()
f = file('poem.txt')
while True:
    line = f.readline()
    if len(line) == 0:
        break
    print line,
f.close()

2.儲存器

import cPickle as p
shoplistfile = 'shoplist.data' #name
shoplist = ['apple', 'mango', 'carrot'] #thing
f = file(shoplistfile, 'w') #read
p.dump(shoplist, f) #store
f.close() #close
del shoplist  #del thin
f = file(shoplistfile) #read
storedlist = p.load(f) #load and read
print storedlist #show

第十三章 異常

1.處理異常

import sys
try:
    s = raw_input('Enter something --> ')
except EOFError:
    print '\nWhy did you do an EOF on me?'
    sys.exit()
except:
    print '\nSome error/exception occurred.'
print 'Done'

2.如何引起異常

class ShortInputException(Exception):
    '''A user-defined exception class.'''
    def __init__(self, length, atleast):
        Exception.__init__(self)
        self.length = length
        self.atleast = atleast
try:
    s = raw_input('Enter something --> ')
    if len(s) < 3:
        raise ShortInputException(len(s), 3)
except EOFError:
    print '\nWhy did you do an EOF on me？'
except ShortInputException, x:
    print 'ShortInputException: The input was of length %d, \
was expecting at least %d' % (x.length, x.atleast)
else:
    print 'No exception was raised'

3.運行過程當中手動停止，ctr-c，會發生鍵盤中斷異常

import time
try:
    f = file('poem.txt')
    while True:
        line = f.readline()
        if len(line) == 0:
            break
        time.sleep(2)
        print line,
finally:
    f.close()
    print 'Cleaning up...closed the file'

第十四章 python標準庫

1.sys模塊 -- 命令行參數

import sys
def readfile(filename):
    '''Print a file to the standard output.'''
    f = file(filename)
    while True:
        line = f.readline()
        if len(line) == 0:
            break
        print line,
    f.close()
if len(sys.argv) < 2:
    print 'No action specified.'
    sys.exit()
if sys.argv[1].startswith('--'):
    option = sys.argv[1][2:]
    if option == 'version':
        print 'Version 1.2'
    elif option == 'help':
        print '''\
This program prints files to the standard output.
Any number of files can be specified.
Options include:
  --version  :  Prints the version number
  --help     :  Display this help'''
    else:
        print 'Unkown option.'
    sys.exit()
else:
    for filename in sys.argv[1:]:
        readfile(filename)

2.os 模塊

os.name --指示當前使用平臺  對windows, 返回'nt'，對於linux等，返回'posix'.
os.getcwd()獲得當前工做目錄 os.getenv()/putenv()  讀取和設置環境變量
os.listdir()返回指定目錄下的全部文件和目錄名    os.remove()
os.system()運行shell腳本    os.sep取代了當前系統的路徑分隔符
os.linesep給出當前平臺的行終止符   os.path.split()返回一個路徑的目錄名和文件名
os.path.isfile()/isdir()判斷給出的路徑是一個文件仍是一個目錄
os.path.existe()檢驗給出的路徑是否真實的存在

第十五章 更多python的內容

1.特殊的方法

__init__    __del__     __str__     __lt__
__getitem__ __len__

2.單語句塊 / 列表綜合

listone = [2, 3, 4,100]
listtwo = [2*i for i in listone if i > 2]
print listtwo

3.在函數中接受元組和列表，*前綴存儲爲一個元組，**前綴則存儲爲一個字典的鍵值對

def powersum(power, *args):
    '''Return the sum of each argument raised to
specified power.'''
    total = 0
    for i in args:
        total += pow(i, power)
    return total
print powersum(2, 3, 4)
print powersum(2, 10)

4.lambda 形式 lambda參數:表達式

def make_repeater(n):
    return lambda s: s*n
twice = make_repeater(2)
print twice('word')
print twice(5)

5.exec和eval語句 exec來執行儲存在字符串和文件中的python語句。 eval來計算存儲在字符串中的有效python表達式

exec 'print "Hello World"'
print eval ('2*3')

6.assert語句 用來聲明某個條件是真的

mylist = ['item']
assert len(mylist) >= 1
mylist.pop()
assert len(mylist) >= 1

7.repr函數，用來取得對象的規範字符串表示

i = []
i.append('item')
print `i`
print repr(i)