2018-11-30 15:45:55
''' 列表 ''' # list.count(x): 返回x在列表中出现的次数 a1 = [1,123.25,333,333,456.5] print(a1.count(333),a1.count(123.25),a1.count(4)) # list.inster(i,x): 在索引号为i的元素前插入元素x a2 =[2,123.25,333,333,456.5] a2.insert(2,-1) print('a2:',a2) # #a.insert(len(a),x):在列表的末尾添加x a3 =[3,123.25,333,333,456.5] a3.insert(len(a3),222) print('a3:',a3) # #a.append(x):在列表末尾添加x a4 =[3,123.25,333,333,456.5] a4.append(222) print('a4:',a4) #a.index(x):返回值为x的索引号 a5 =[3,123.25,333,333,456.5] print('a5:',a5.index(3)) #a.remove(x):移除列表中的元素x a6 =[3,123.25,333,333,456.5] a6.remove(3) print('a6:',a6) #a.reverse():列表中的元素倒排序 a7 =[3,123.25,333,333,456.5] a7.reverse() print('a7:',a7) #对列表中的元素进行排序 a8 =[3,123.25,333,333,456.5] a8.sort() print('a8:',a8) #list.pop():从列表中移除最后一个元素 a9 =[3,123.25,333,333,456.5] a9.pop() print('a9:',a9) #list.pop(i):从列表中移除索引为i的元素 a10 =[3,123.25,333,333,456.5] a10.pop(1) print('a10:',a10) ''' 将列表当做对堆栈使用 ''' #后进先出 stack = [1,2,3,4,5,6] stack.append(7) print(stack) stack.append(8) print(stack) stack.pop() print(stack) stack.pop() print(stack) ''' 将列表当作队列使用 ''' from collections import deque queue = deque(['google','runoob','taobao']) print('1:',queue) queue.append('baidu') queue.append('tianmao') print('2',queue) print(queue.popleft()) #从左边开始弹出，弹出后其他一个一个往前移动 print(queue.popleft()) print('3:',queue) ''' 列表推导式 ''' #将列表的值都乘以3后输出 vec1 = [2,4,6] vec12 = [3*x for x in vec1] print('1:',vec12) #按要求生成子列表 vec2 = [2,4,6] vec21 = [[x,x**2] for x in vec2] print('2:',vec21) #对列表中对每个元素调用某方法 freshfruit = ['apple','banan','orange'] freshfruit1 = [weapon.strip() for weapon in freshfruit] print('freshfruit1:',freshfruit1) #使用ifz作为过滤器 vec3 = [2,4,6] vec31 = [3*x for x in vec3 if x >3] print('vec31:',vec31) vec32 = [3*x for x in vec3 if x <5] print('vec32:',vec32) #其他一些技巧演示 vec4 = [1,2,3] vec5 = [4,5,-6] vec451 = [x*y for x in vec4 for y in vec5] print('vec451',vec451) vec452 = [x+y for x in vec4 for y in vec5] print('vec452:',vec452) pass pass ''' 嵌套列表解析 ''' pass #del list[]:通过索引删除列表中的某个元素 d1 = [1,2,3,4,5,6,7] del d1[0] print('d1:',d1) #删除对元素个数4-2=2个，从开始对索引开始删除 d2 = [0,1,2,3,4,5,6,7] del d2[2:4] print('d2:',d2) #del list[:]:删除列表中对所有元素 d3 = [0,1,2,3,4,5,6,7] del d3[:] print('d3:',d3) #del d:删除一个实体变量 # d4 = [0,1,2,3,4,5,6,7] # del d4 # print('d4:',d4) ''' 元组和序列 ''' #元组对输出总是有圆括号对，输入可以有可以没有 t = (123,456,'hello') print(t[0]) print('t：',t) u = (t,(78,89,90)) print(u) #元组输入时可以没有圆括号 t1 = 1,2,3 print('t1',t1) ''' 集合 ''' basket = {'apple','banana','orange','pear','apple','banana'} #字典的基本功能：消除重复元素 print(basket) #字典的基本功能：关系测试 print('apple' in basket) print('runoob' in basket) #set():创建集合 a = set('abcdeabc') b = set('cdefghrr') #集合去重操作 print(a) #在a中但不在b中的 print(a-b) #不同时在a或者b中 print(a^b) #a和b的并集 print(a|b) #a和b的交集 print(a&b) #集合也支持推导式 c = {x for x in a if x not in b} print(c) ''' 字典 ''' #使用{}创建字典 tel = {'jack01':6001,'jack02':6002,'jack03':6003} #向字典中添加元素 tel1 = {'jack01':6001,'jack02':6002,'jack03':6003} tel1['jack04'] = 6004 print('tel1：',tel1) #del dict[键]：通过键值删除字典中的某个元素 tel2 = {'jack01':6001,'jack02':6002,'jack03':6003} del tel2['jack01'] print('tel2:',tel2) #打印出字典的键值列表 tel3 = {'jack01':6001,'jack02':6002,'jack03':6003} print('tel3:',list(tel3.keys())) #打印出字典的键值列表并排序 tel4 = {'jack01':6001,'ajack02':6002,'bjack03':6003} print('tel4:',sorted(tel4.keys())) #关系测试 tel5 = {'jack01':6001,'ajack02':6002,'bjack03':6003} print('tel51:','jack01' in tel5) print('tel52：','jack02' in tel5) #构造函数dict()直接从键值队元=组列表中构建字典 tel6 = dict([('jack01',7001),('jack2',7002),('jack3',7003)]) print(tel6) #字典推导 dict1 = {x:x**2 for x in (2,4,6) } print(dict1) #如果关键字只是简单对字符串，使用关键字参数指定键值对有时更方便 dict2 = dict(jack01=2001,jack02=2002,jack03=2003) print(dict2) ''' 遍历技巧 ''' #字典中遍历时，关键字和对值可以使用item（）遍历出来 knights = {'jack01':'good','jack02':'better','jack03':'best'} for k,v in knights.items(): print(k,v) #在遍历列表时，索引值和对应值可以使用enumerate()函数同时得到 for k,v in enumerate(['jack01','jack02','jack03']): print(k,v) #zip()# 遍历两个或更多序列 questions=['name','age','class'] answers=['jack',18,'class1'] for q,a in zip(questions,answers): print("'what's your{0}? It is {1}".format(q,a)) #反向遍历一个序列用reversed() for i in reversed(range(1,10,2)): print('反向遍历：',i) #sorted()按顺序遍历 str1 = ['a','b','d','e'] for i in sorted(str1): print('sorted():',i)