improve your python code(9)

1. 字符串处理小结

#!/usr/bin/env python# encoding: utf-8"""@python version: python3.6.1@author: XiangguoSun@contact: [e-mail]@site: http://blog.csdn.net/github_36326955@software: PyCharm@file: strmethod.py@time: 5/7/2017 12:45 PM""""""字符串操作"""s = "   I like   the Tian'anmen Square    of the Capital Beijing.  "print(s.count('the'))   # output:2print("Beijing" in s)   # output: trueres = s.replace('.', '!')print(s, "| ", res)"""output:   I like   the Tian'anmen Square    of the Capital Beijing.   |     I like   the Tian'anmen Square    of the Capital Beijing!"""pre, key, post = s.partition("Tian'anmen Square")print(pre,"|",key,"|",post)"""output:   I like   the  | Tian'anmen Square |     of the Capital Beijing."""print(s.split())print(s.split(" "))"""output:['I', 'like', 'the', "Tian'anmen", 'Square', 'of', 'the', 'Capital', 'Beijing.']['', '', '', 'I', 'like', '', '', 'the', "Tian'anmen", 'Square', '', '', '', 'of', 'the', 'Capital', 'Beijing.', '', '']"""print(s.title())import stringprint(string.capwords(s))"""output:   I Like   The Tian'Anmen Square    Of The Capital Beijing.I Like The Tian'anmen Square Of The Capital Beijing."""word_list = s.split()print("居中对齐：")for word in word_list:    print(word.center(10))print("左对齐")for word in word_list:    print(word.ljust(10))print("0填充")for word in word_list:    print(word.zfill(5))"""output:居中对齐：    I   like   theTian'anmen  Square    of   the Capital Beijing.左对齐IliketheTian'anmenSquareoftheCapitalBeijing.0填充0000I0like00theTian'anmenSquare000ofCapitalBeijing."""print(s)print(s.strip())"""output:   I like   the Tian'anmen Square    of the Capital Beijing.I like   the Tian'anmen Square    of the Capital Beijing."""print(s)print(" ".join(s.split()))"""output:   I like   the Tian'anmen Square    of the Capital Beijing.I like the Tian'anmen Square of the Capital Beijing."""

2.operator.itemgetter函数

operator模块提供的itemgetter函数用于获取对象的哪些维的数据，参数为一些序号（即需要获取的数据在对象中的序号），如若你用过padas、numpy的话，相信你对这个概念会理解。相当于那里的axis。下面看例子。

a = [1,2,3] b=operator.itemgetter(1)     #定义函数b，获取对象的第1个域的b(a) 2 b=operator.itemgetter(1,0)   #定义函数b，获取对象的第1个域和第0个的值b(a) (2, 1)

用 operator 函数进行多级排序

students = [('john', 'A', 15), ('jane', 'B', 12), ('dave', 'B', 10),]  sorted(students, key=itemgetter(1,2))"""sort by grade then by age"""  [('john', 'A', 15), ('dave', 'B', 10), ('jane', 'B', 12)]  

对字典排序

d = {'data1':3, 'data2':1, 'data3':2, 'data4':4}  sorted(d.iteritems(), key=itemgetter(1), reverse=True)  [('data4', 4), ('data1', 3), ('data3', 2), ('data2', 1)]

3. sort与sorted

persons = [{'name':'Bon','age':32},           {'name':'Alan','age':50},           {'name':'Bon','age':33},           {'name':'Job','age':23}]"""sort与sorted原型：sorted(iterable[,cmp[,key[,reverse]]])s.sort([cmp[,key[,reverse]]])cmp:比较函数key:带一个参数的函数，用于提取每个元素的比较值，默认为Nonereverse：表示结果是否反转""""""先按照name有小到大排序。对于name相同的，则按照age有小到大排序"""print(sorted(persons, key = lambda x:(x['name'],x['age'])))print(persons)persons.sort(key = lambda x:(x['name'],x['age']))print(persons)print(persons.sort(key = lambda x:(x['name'],x['age'])))"""output[{'name': 'Alan', 'age': 50}, {'name': 'Bon', 'age': 32}, {'name': 'Bon', 'age': 33}, {'name': 'Job', 'age': 23}][{'name': 'Bon', 'age': 32}, {'name': 'Alan', 'age': 50}, {'name': 'Bon', 'age': 33}, {'name': 'Job', 'age': 23}][{'name': 'Alan', 'age': 50}, {'name': 'Bon', 'age': 32}, {'name': 'Bon', 'age': 33}, {'name': 'Job', 'age': 23}]Nonesorted会返回一个排序后的列表，原有的列表不变而sort会直接修改原有列表，函数返回None.""""""sorted()作用于任意可迭代对象，而sort一般作用于列表:"""a_tuple = (1,2,4,2,3)# print(a_tuple.sort()) # 报错print(sorted(a_tuple))    # 正确 [1, 2, 2, 3, 4]from operator import itemgetter"""对字典排序："""phonebook = {'Linda':'7750','Bob':'9345','Carol':'5834'}sorted_pb = sorted(phonebook, key=itemgetter(1))    # 按照数字大小进行排序print(sorted_pb)"""多维list排序："""gameresult = [['Bob',95,'A'],['Alan',86,'C'],['Mandy',82,'A'],['Rob',86,'E']]print(sorted(gameresult,key=itemgetter(2,1)))from operator import itemgetter"""字典中混合list"""mydic = {'Li':['M',7],         'Lh':['M',6],         'Zhang':['E',2],         'Wang':['P',3],         'Du':['C',9],         'Ma':['C',2],         'Zhe':['H',7]    }"""下面的k=('Li':['M',7])"""print(sorted(mydic.items(),key=itemgetter(0)))      # 按照'Li'排序print(sorted(mydic.items(),key=lambda k:itemgetter(1)(k[1])))   # 按照7排序print(sorted(mydic.items(),key=lambda k:itemgetter(0)(k[1])))   # 按照'M'排序"""output:[('Du', ['C', 9]), ('Lh', ['M', 6]), ('Li', ['M', 7]), ('Ma', ['C', 2]), ('Wang', ['P', 3]), ('Zhang', ['E', 2]), ('Zhe', ['H', 7])][('Zhang', ['E', 2]), ('Ma', ['C', 2]), ('Wang', ['P', 3]), ('Lh', ['M', 6]), ('Li', ['M', 7]), ('Zhe', ['H', 7]), ('Du', ['C', 9])][('Du', ['C', 9]), ('Ma', ['C', 2]), ('Zhang', ['E', 2]), ('Zhe', ['H', 7]), ('Li', ['M', 7]), ('Lh', ['M', 6]), ('Wang', ['P', 3])]""""""list中混合字典；"""game = [{'name':'a','grade':2},{'name':'b','grade':1}]print(sorted(game,key=itemgetter('grade')))"""output:[{'name': 'b', 'grade': 1}, {'name': 'a', 'grade': 2}]"""