【UNFinish】Python Day 15

# 剩余 内置函数

# 数据类型：int bool……
# 数据结构：dict list tuple set str

# l = [1,2,3,4,5]
# l.reverse()
# print(l) #反转 [5, 4, 3, 2, 1]
#
# l2 = [1,2,3,4,5]
# ret = reversed(l2)
# print(ret) # <list_reverseiterator object at 0x10391b550>不改变原来的列表，返回一个反向的迭代器
#
# l = (1,2,34,213,5612,342,43)
# sli = slice(1,5,2)
# print(l[sli]) # (2, 213)

# print(format('test','<20')) # 左对齐
# print(format('test','>20')) # 右对齐
# print(format('test','^20'))# 居中显示

# bytes 转换成bytes类型
# print(bytes('你好',encoding='GBK')) # b'\xc4\xe3\xba\xc3' Unicode转换成GBK
# print(bytes('你好',encoding='utf-8')) # b'\xe4\xbd\xa0\xe5\xa5\xbd' Unicode转换成UTF-8
# print(bytes('你好',encoding='GBK').decode('GBK')) # 你好
# print(bytes('你好',encoding='utf-8').decode('UTF-8')) # 你好
# gbk转换成utf-8
# 先将GBK转换成unicode，再将Unicode转换成UTF-8

# 网络编程 只能转二进制
# 文件存储
# 照片和视频 也是以二进制存储
# html网页爬取到的也是编码

# bytearray修改字符串的时候，可以转换成byte的方式，可以节省内存
# b_array= bytearray('你好',encoding='UTF-8')
# print(b_array) # bytearray(b'\xe4\xbd\xa0\xe5\xa5\xbd')
# print(b_array[0]) # 228

# 切片：字节类型 不占内存
# 字节：换成字符串，占据内存
# print(memoryview(bytes('你好',encoding='UTF-8'))) # <memory at 0x10401aac8>

# 字符按照Unicode转数字
# print(ord('a')) # 97
# # 数字按照Unicode转字符
# print(chr(97)) # a
# # 只要是ascii中的内容，就打印出来，不是就转成\u
# print(ascii('好')) # '\u597d'
# print(ascii('123')) # '123'


# # repr带着字符类型打印
# name = 'fangfang'
# print('你好%s'%name) # 你好fangfang
# print('你好%r'%name) # 你好'fangfang'
#
# print(repr('1')) # '1'
# print(repr(1)) # 1


# # ALL：可迭代内容里面有任意一个值是0，则整个为0
# print(all(['a','','123'])) # False
# print(all(['a','123'])) # True
# print(all([0,'123'])) # False
#
# # Any：可迭代内容里面所有值是0，则整个为0
# print(any(['','',0])) # False
# print(any(['a','123'])) # True
# print(any([0,'123'])) # True

# # zip
# l = [1,2,3]
# l2 = ['a','b','c','d']
# l3 = ('*','**',[1,2,3])
# l4 = {'k1':'v1','k2':'v2'}
# print(zip(l,l2)) # <zip object at 0x104108988> 是一个迭代器
# for i in zip(l,l2,l3,l4):
#     print(i)\
#         (1, 'a', '*', 'k1')
# (2, 'b', '**', 'k2')

# filter
# def is_odd(x):
#     return x%2 == 1
# def is_str(s): # 过滤字符串
#     return type(s) == str
# def is_delete_empty(s): # 过滤空数据
#     return str(s) and str(s).strip()
# ret = filter(is_delete_empty,[1,2,'hello',23,None,'world',7,' ',[],'hehe'])
# for i in ret:
#     print(i) # 1 3 23 7
# print([i for i in [1,2,3,23,6,7] if i%2 == 1 ]) # [1, 3, 23, 7]
#
# from math import sqrt
# def function(x):
#     return sqrt(x)%1 == 0
# ret = filter(function,range(1,101))
# print(ret) # <filter object at 0x104102518>
# for i in ret:
#     print(i)

# MAP
# ret = map(abs,[1,-4,6,-8]) #
# print(ret) # <map object at 0x104100588>
# for i in ret:
#     print(i) # 1 4 6 8

# filter：执行了filter之后的结果集合 <= 执行之前的个数
#         filter只管筛选，不会改变原来的值

# map：执行前后元素个数不变
#     值可能发生改变

# Sort：在原列表的基础上进行排序
# Sorted：生成一个新列表 不改变原列表 占内存
# l = [1,-4,6,5,-10]
# print(sorted(l)) # [-10, -4, 1, 5, 6] 默认从小到大排序
#
# l = [1,-4,6,5,-10]
# l.sort(key = abs)
# print(l) # [1, -4, 5, 6, -10]
#
# l = [1,-4,6,5,-10]
# print(sorted(l,key = abs,reverse=True)) # [-10, 6, 5, -4, 1]
# print(sorted(l,key = abs,reverse=False)) # [1, -4, 5, 6, -10]
# print(sorted(['  ',[1,2],'hello world'],key = len,reverse=False)) # ['  ', [1, 2], 'hello world']
# print(sorted(['  ',[1,2],'hello world'],key = len,reverse=True)) # ['hello world', '  ', [1, 2]]


# 匿名函数
# 函数名 = lambda 参数 ： 返回值
# add = lambda x,y:x+y
# print(add(1,2))

# dic = {'k1':10,'k2':20,'K3':30}
# print(max(dic,key=lambda k:dic[k])) # 筛选字典里面value对应的key
# Min max map filter sorted都可以和lambda合作

# #
# d = lambda p:p*2
# t = lambda p:p*3
# x = 2
# x = d(x)
# x = t(x)
# x = d(x)
# print(x) # 24

# 现有2个元祖(('a'),('b')),(('c'),('d'))，请使用python中的匿名函数生成列表[{'a':'c'},{'b':'d'}]
# 匿名函数 == 内置函数
# zip
# ret = zip((('a'),('b')),(('c'),('d')))
# res = map(lambda tup:{tup[0]:tup[1]},ret)
# print(list(res))

# # 枚举 enumerate
# for i,j in enumerate(('a','b','c')):
#     print(i,j)
# 0 a
# 1 b
# 2 c

# for i,j in enumerate(['a','b','c']):
#     print(i,j)
# 0 a
# 1 b
# 2 c

# for i,j in enumerate({'a':1,'b':2}):
#     print(i,j)
# 0 a
# 1 b