一. 列表、字典、集合、元組的使用

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from random import randint, sample

# 列表解析

data = [randint(-10, 10) for _ in xrange(10)]

filter(lambda x: x >= 0, data)

[x for x in data if x >= 0] #最快速

# 字典解析

d = {x: randint(60, 100) for x in xrange(1,21)}

{k : v for k, v in d.iteritems() if v > 90}

# 集合解析

s = set(data)

{x for x in s if x % 3 ==0}

# 元組

student = ('Jim', 16, 'male', 'jim@qq.com')

# 1. enum

NAME, AGE, SEX, EMAIL = xrange(4)

print student[NAME]

# 2.

from collections import namedtuple

Student = namedtuuple('Student', ['name', 'age', 'sex', 'email'])

s2 = Student('Tom', 16, 'mail', 'tom@qq.com')

print s2.name

# 統(tǒng)計(jì)列表的重復(fù)元素

li = [randint(0, 20) for _ in xrange(30)]

d = dict.fromkeys(li, 0)

# 1.

for x in li: d[x] += 1

# 2.

from collections import Counter

d2 = Counter(li)

d2.most_common(3) #重復(fù)數(shù)高的三個(gè)元素

# 字典根據(jù)值value排序

sorted([3, 1, 5]) #排序列表

(97, 'a') > (88, 'b') # 元組的比較，每個(gè)元素從開始比較

d = {x: randint(60, 100) for x in 'abcde'}

# 1.

data = zip(d.itervalues(), d.iterkeys())

sorted(data)

# 2.

sorted(d.items(), key=lambda x: x[1])

# 多個(gè)字典中的公共鍵

sample('abcdefg', 3)

sample('abcdefg', randint(3,6)) # 隨機(jī)取出幾個(gè)元素

s1 = {x: randint(1,4) for x in sample('abcdefg', randint(3.6))}

s2 = {x: randint(1,4) for x in sample('abcdefg', randint(3.6))}

s3 = {x: randint(1,4) for x in sample('abcdefg', randint(3.6))}

# 1.

res = []

for k in s1: if k in s2 and k in s3: res.append(k) # res.pop(k)

# 2. 使用集合

res = s1.viewkeys() & s2.viewkeys() & s3.viewkeys()

# 3.

m1 = map(dict.viewkeys, [s1, s2, s3])

res = reduce(lambda a, b: a & b, m1)

# 保持字典有序

d = {'Jim':(1, 35), 'Leo':(2, 38), 'Tom':(3, 44)}

from collections import OrderedDict

d = OrderedDict() #按進(jìn)入字典的順序打印

d['Jim'] = (1,35)

d['Leo'] = (2,38)

d['Tom'] = (3,44)

from time import time

start = time()

raw_input() #等待輸入

# ...

timesecond = time() - start

# 歷史記錄

# 1. 用隊(duì)列存儲(chǔ)

from collections import deque

q = deque([], 5)

q.append(1) # 達(dá)到長(zhǎng)度后，先進(jìn)先出

li = list(q) # 轉(zhuǎn)換成列表類型

# 2. 將q存到文件中

import pickle

pickle.dump(q, open('test','w'))

q2 = pickle.load(open('test','r'))

二. 迭代器、生成器

# 實(shí)現(xiàn)可迭代對(duì)象、迭代器對(duì)象

# 用時(shí)訪問 并封裝到一個(gè)對(duì)象中

# 可迭代對(duì)象

li = [1,2,3,4]

str= 'abcde'

# 迭代器

iterl = iter(li) # li.__iter__()

iters = iter(str) # str.__getitem__()

iterl.next()

# 1. 城市天氣的迭代器和可迭代對(duì)象

from collections import Iterable, Iterator

class WIterator(Iterator):

def __init__(self, cities):

self.cities = cities

self.index = 0

def getWeather(city):

import requests

r = requests.get(u'http://wthrcdn.etouch.cn/weather_mini?city=' + city)

data = r.json()['data']['forecast'][0]

return '%s: %s, %s' % (city, data['low'], data['high'])

def next(self):

if self.index == len(self.cities)

raise StopIteration

city = self.cities[self.index]

self.index += 1

return self.getWeather(city)

class WIterable(Iterable):

def __init__(self, cities):

self.cities = cities

def __iter__(self):

return WIterator(self.cities)

for x in WIterable([u'北京', u'長(zhǎng)沙', u'廣州'])：

print x

# 2. 使用生成器函數(shù)實(shí)現(xiàn)可迭代對(duì)象

def f():

print 'in f(), 1'

yield 1

print 'in f(), 2'

yield 2

g = f() # g.__iter__()

for i in g: print i

class PrintNumbers:

def __init__(self, start, end):

self.start = start

self.end = end

def isPrimeNum(self, k):

if k % 2 == 0:

return True

else:

return False

def __iter__(self):

for k in xrange(self.start, self.end+1):

if self.isPrimeNum(k):

yield k

for x in PrintNumbers(1, 100): print x

# 進(jìn)行反向迭代

li = [1,2,3,4,5]

li.reverse() # 改變?cè)瓉砹斜?/p>

li[::-1] # 切片，和原來列表等大的新列表

ll = li.reversed(li) # 列表反向迭代

for i in ll: print i

class FloatRange:

def __init__(self, start, end, step=0.1)

self.start = start

self.end = end

self.step = step

def __iter__(self):

t = self.start

while t <= self.end:

yield t

t += self.step

def __reversed__(self):

t = self.enf

while t >= self.start:

yield t

t -= self.step

# 正向迭代

for i in FloatRange(1.0, 4.0, 0.5): print x

# 反向迭代

for i in reversed(FloatRange(1.0, 4.0, 0.5)): print x

# 對(duì)迭代器做切片操作

from itertools import islice

# islice()

li = range(20)

t = iter(li)

for x in islice(t, 5, 10): print x # 會(huì)消耗原來的迭代對(duì)象

# 在一個(gè)for中迭代多個(gè)可迭代對(duì)象

chinese = [randint(60,100) for _ in xrange(40)]

math = [randint(60,100) for _ in xrange(40)]

english = [randint(60,100) for _ in xrange(40)]

for in in xrange(len(math)):

print chinese[i] + math[i] + english[i]

total = []

# 并行多個(gè)可迭代對(duì)象

for c, m, e in zip(chiness, math, english)

print c+m+e

# 1. 串連多個(gè)迭代對(duì)象

from itertools import chain

c1 = [randint(60,100) for _ in xrange(40)]

c2 = [randint(60,100) for _ in xrange(42)]

c3 = [randint(60,100) for _ in xrange(45)]

for s in chain(c1, c2, c3):

if s > 90: print s

三. 字符串

# 拆分含多種分隔符的字符串

s = "fwerf sd123 ^sdf dfdsf*d dsf 123"

s.split(“xy”) #默認(rèn)以空格分割，或以參數(shù)分割

res = s.split(";")

map(lambda x: x.split("|"), res) # 以";"和"|"分割的二維數(shù)組

t = []

map(lambda x: t.extend(x.split("|")), res) # 二維元素放到t中

# 1.

def aSplit(s, ds):

res = [s]

for d in ds:

t = []

map(lambda x: t.extend(x.split(d)), res)

res = t

return res

print aSplit(s, " ^*") # 會(huì)存在空的元素

# 2. 正則表達(dá)式

import re

re.split(r'[,;|]+', s)

# 判斷字符串a(chǎn)是否以b開頭或結(jié)尾

#s.startswith() s.endswith() 接收單個(gè)字符串或字符串元組

import os, stat

files = [name for name in os.listdir(".") if name.endswith(('.sh', '.py'))]

# 調(diào)整字符串中文本的格式

#日志中'yyyy-mm-dd' 改為 'mm/dd/yyyy'

import re

log = open("/var/log/dpkg.log").read()

re.sub('(\d{4})-(\d{2})-(\d{2})', r'\2/\3/\1', log)

re.sub('(?P\d{4})-(?P\d{2})-(?P\d{2})', r'\g/\g/\g', log)

# 多個(gè)小字符串拼接成大字符串

s1 = "abcde"

s2 = "12345"

s1 + s2 # str.__add__(s1, s2) str.__gt__(s1, s2) 運(yùn)算符重載

s = ""

for p in pl: s += p # 變量多時(shí)，臨時(shí)變量開銷大，資源浪費(fèi)

s.join(s1) # 參數(shù)可為字符串，可為列表

li = ['avc', 123, 'xyz', 456]

''.join([str(x) for x in li]) #列表解析，會(huì)生成一個(gè)列表，開銷大

''.join(str(x) for x in li) #生成器, (str(x) for x in li) 作為參數(shù)是括號(hào)省略

# 字符串格式對(duì)齊

# str.ljust() str.rjust() str.center()

s = "abc"

s.ljust(10 ,'=') # 左對(duì)齊，填充=

s.center(10)

format(s, '<20') # 左對(duì)齊

format(s, '>20') # 右對(duì)齊

format(s, '^20') # 居中

# 去掉字符串中不需要的字符

s = ' -------sd dfadf 2332 +++++++++'

s.strip(' -+')

s.lstrip()

s.rstirp()

# 刪除固定位置的字符,拼接切片

s[:3]+ s[4:]

# 替換

s.replace('\t', '')

import re

re.sub('[\t\r]', '', s)

s = 'abc123e3rxyz'

#s.translate()

import string

tr = string.maketrans('abcxyz', 'xyzabc')

s.translate(tr)

s = 'abc\rdfd\n234234\t'

s.translate(None, '\r\t\n')

四. 文件讀寫

# python2 str unicode

# python3 bytes str

# python2

s = u'你好'

s.encode('utf8') #存儲(chǔ)到文件中的格式

f = open('hello.txt', 'w')

f.write(s.encode('utf8'))

f.close()

f = open('hello.txt', 'r')

t = f.read().decode('utf8') # 你好

f.close()

# python3 字符串就是unicode

strb = b'asdfasdfsdg'

s = '你好'

f = open('hello2.txt', 'wt', encoding='utf8') # 自動(dòng)完成編解碼

f.write(s)

f.close()

f = open('hello2.txt', 'rt', encoding='utf8')

s = f.read()

f.close()

# 處理二進(jìn)制文件 處理音頻文件，將音量調(diào)小保存

f = open('demo.wav', 'rb')

info = f.read(44) #文件頭

import struct

struct.unpack('h',info[22:24]) #處理文件頭 數(shù)據(jù)運(yùn)算

struct.unpack('i',infi[24:28])

f.seek(0,2)

f.tell()

n = (f.tell()-44) /2

import array

buf = array.array('h', (0 for _ in xrange(n)))

f.seek(44)

f.readinto(buf)

for i in xrange(n): buf[i] /= 8

f2 = open('demo2.wav', 'wb')

f2.write(info)

buf.tofile(f2)

f2.close()

# 使用臨時(shí)文件

# 自動(dòng)刪除，不占內(nèi)存

from tempfile import TemporaryFile, NamedTemporaryFile

f = TemporaryFile() # 系統(tǒng)文件系統(tǒng)找不到

f.write('abcddee'*100000)

f.seek(0)

f.read(100)

ntf = NamedTemporaryFile(delete=False) # 能找到文件，默認(rèn)關(guān)閉以后會(huì)刪除文件

fname = nft.name

# 設(shè)置文件的緩沖

# I/O 操作以塊為單位，如4096字節(jié)一個(gè)塊

f = open('test.txt', 'w'， buffering=2048) # 全緩沖，要寫滿緩沖才會(huì)寫到文件中

f = open('test.txt', 'w'， buffering=1) # 行緩沖，\n就會(huì)寫文件

f = open('test.txt', 'w'， buffering=1) # 無緩沖，實(shí)時(shí)寫

f.write('abc')

# 將文件映射到內(nèi)存

import mmap

f = open('demo.bn','r+b')

f.fileno()

m = mmap.mmap(f.fileno(), 0, access=mmpa.ACCESS_WRITE, offset=mmap.PAGESIZE)

# 得到字節(jié)數(shù)組

m[4:8] = '\xff'*4 # 修改直接改變文件內(nèi)容

# 讀寫csv數(shù)據(jù)

from urllib import urlretrieve

urlretrieve('http://table.finance.yahoo.com/table.csv?s=000001.sz', 'pingan.csv')

rf = open('pingan.csv', 'rb')

import csv

reader = csv.reader(rf)

header = reader.next()

wf = open('pingan_c.csv', 'wb')

writer = csv.writeer(wf)

writer.writerow(header)

rf.close()

wf.close()

# 讀寫json數(shù)據(jù)

import requests

import json

from record import Record

record = Record(channel=1)

audioData = record.record(2)

from secret import API_KEY, SECRET_KEY

authUrl = "https://openapi.baidu.com/oauth/2.0/token?grant_type=client_credentials&client_id=" + API_KEY + "&client_secret=" + SECRET_KEY

response = requests.get(authUrl)

res = json.loads(response.content)

token = res['access_token']

#百度語音識(shí)別

cuid = 'xxxxxxxxxxxxx'

srvUrl = 'http://vop.baidu.com/server_api?cuid=' + cuid + '&token=' + token

heepHeader = {'Content-Type': 'audio/wav; rate = 8000'}

response = requests.post(srvUrl, headers=httpHeader, data=audioData)

res = json.loads(response.content)

text = res['result'][0]

print text

# json.dumps() python對(duì)象(列表、字典等)轉(zhuǎn)換成json字符串

# json.dumps(data, sort_keys=True)

# json.loads() json字符串轉(zhuǎn)換成python對(duì)象

with open('demo.json', 'wb') as f:

json.dump(l, f) # 將l數(shù)據(jù)寫到文件

# 構(gòu)建xml文檔

from xml.etree.ElementTree import parse

with open('demo.xml') with f:

et = parse(f)

root = et.getroot()

root.tag

root.attrib

root.text

#root.getchildren()

for child in root:

print child.get('name')

root.find('country')

root.findall('country') # 直接子元素

for e in root.iterfind('country'):

print e.get('name')

from xml.etree.ElementTree import Element, ElementTree, tostring

e = Element('Data')

e.set('name', 'abc')

e2 = Element('Row')

e3 = Element('Open')

e3.text = '8.80'

e2.append(e3)

e.append(e2)

tostring(e)

et = ElementTree(e)

et.write('demo.xml')

# 讀寫excel文件

import xlrd, xlwt

book = xlrd.open_workbook('demo.xls')

book.sheets()

sheet = book.sheet_by_index(0)

rows = sheet.nrows

cols = sheet.ncols

cell = sheet.cell(0,0) #(0,0)單元格

cell.ctype

cell.value

row = sheet.row(1) #cell對(duì)象列表

data = sheet.row_values(1, 1) #第1列跳過第一格的值列表

sheet.put_cell(0, cols, xlrd.XL_CELL_TEXT, u'Total', None)

wbook = xlwt.Workbook()

wsheet = wbook.add_sheet('sheet1')

style = xlwt.easyxf('align: vertical center, horizontal center')

wsheet.write(rows,cols, sheet.cell_value(rows,cols), style)

wsheet.save('output.xls')

五. 派生內(nèi)置不可變類型并修改其實(shí)例化行為

class IntTuple(tuple):

def __new__(cls, iterable): #先于__init__()調(diào)用

g = (x for x in iterable if isinstance(x, int) and x > 0)

super(IntTuple, cls).__new__(cls, g)

def __init__(self, iterable):

# 此時(shí)如果過濾iterable 無法過濾成功

super(IntTuple, self).__init__(iterable)

t = IntTuple([1, -1, 'abc', 6, ['x', 'y'], 3])

print t?無錫婦科醫(yī)院排名 http://www.csyhjlyy.com/

六. 使用描述符對(duì)實(shí)例屬性做類型檢查

# 描述符： 包含 __get__() __set__() __delete__() 函數(shù)的類

class Attr(object):

def __init__(self, name, type_):

self.name = name

self.type_= type_

def __get__(self, instance, cls):

return instanse.__dict__[self.name]

def __set__(self, instance, value):

if not isinstance(value, self.type_):

raise TypeError('expected %s' % self.type_)

instance.__dict__[self.name] = value

def __delete__(self, instance):

del instance.__dict__[self.name]

class Person(object):

name = Attr('name', str)

age = Attr('age', int)

hgt = Attr('height', float)

p = Person()

p.name = 'Bob'

print p.name

p.age = '17' #會(huì)拋出異常

七. 在環(huán)狀數(shù)據(jù)結(jié)構(gòu)中管理內(nèi)存

import sys

class A(object):

def __del__(self): # 當(dāng)引用次數(shù)變?yōu)?時(shí)，調(diào)用析構(gòu)函數(shù)

print 'in A.__del__'

a = A()

a2 = a

print sys.getrefcount(a) - 1 # 查看對(duì)象a的引用次數(shù)，參數(shù)名也引用了對(duì)象，要-1

del a

del a2

# 循環(huán)引用

class Data(object): # Data類保存Node對(duì)象引用

def __init__(self, value, owner):

self.owner = owner

self.value = value

def __str__(self):

return "%s's data, value is %s" % (self.owner, self.value)

def __del__(self):

print 'in Data.__del__'

class Node(object): # Node類調(diào)用Data對(duì)象

def __init__(self, valu):

self.data = Data(value, self)

def __del__(self):

print 'in Node.__del__'

node = Node(100)

del node # 此時(shí)Data Node不會(huì)被回收掉

raw_input('wait...')

# 使用弱引用

import weakref

a_wref = weakref.ref(a)

a2 = a_wref()

class Data(object): # Data類保存Node對(duì)象引用

def __init__(self, value, owner):

self.owner = weakref.ref(owner) # 弱引用

self.value = value

def __str__(self):

return "%s's data, value is %s" % (self.owner(), self.value)

def __del__(self):

print 'in Data.__del__'

node2 = node(100)

del node2 # 此時(shí)Data Node將被回收

八. 通過實(shí)例方法名的字符串調(diào)用方法

# Circle Triangle Trctangle 求面積的方法名都不同

# 通過傳方法名來調(diào)用不同的方法

# 1. getattr 獲取對(duì)象屬性，方法名也是屬性

from lib1 import Circle

from lib2 import Triangle

from lib3 import Tectangle

def getArea(shape):

for name in ('area', 'getArea', get_area):

f = getattr(shape, name , None)

if f:

return f()

shape1 = Circle(2)

shape2 = Tirangle(3,4,5)

shape3 = Rectangle(6,4)

shapes = [shape1, shape2, shape3]

print map(getArea, shapes)

# 2. 使用opreator標(biāo)準(zhǔn)庫(kù)

from opreator import methodcaller

s = "abc123abc456"

s.find('abc', 4)

methodcaller('find', 'abc', 4)(s)

九. 為創(chuàng)建大量實(shí)例節(jié)省內(nèi)存

class Player(object):

def __init__(self, uid, name, status=0, level=1):

self.uid = uid

self.name = name

self.stat = status

self.level = level

class Player2(object):

__slots__ = ['uid', 'name', 'stat', 'level']

def __init__(self, uid, name, status=0, level=1):

self.uid = uid

self.name = name

self.stat = status

self.level = level

p1 = Player('0001', 'Jim')

p2 = Player2('0002', 'Tom')

# p1 bi p2 多兩個(gè)屬性 __dict__ __weakref__

# __dict__ 字典，為實(shí)例動(dòng)態(tài)綁定解除新屬性

# p2 則不能動(dòng)態(tài)綁定屬性

# __slots__ 阻止了該功能

十. 讓對(duì)象支持上下文管理

# 要使用上下文管理，類中要定義 __enter__ __exit__方法，分別在with開始和結(jié)束時(shí)調(diào)用

class test(object):

...

def __enter__(self):

pass

def __exit__(self, exc_type, exc_val, exc_tb):

pass

with test() as k:

pass

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