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這里有您想知道的互聯(lián)網(wǎng)營(yíng)銷解決方案
IteratorandGenerator-2
lambda表達(dá)式
匿名函數(shù)
# lambda params:expression
# params : 可選參數(shù)，逗號(hào)分割變量名
# expression：表達(dá)式，可以用條件語(yǔ)句，沒有return或yield
# 用法：
# 簡(jiǎn)單計(jì)算：lambda x: x*2
# 添加條件： lambda x :True if x > 8 else False
# 多個(gè)參數(shù) lambda x, y : x+y
# 用作排序： users.sort(key = lambda x(x[0], x[1]))
# 默認(rèn)字典：①defaultdic(lambda:0)
# ② defaultdict(lambda:'bj')
# ③ defaultdic(lambda :(0, 0))
# 用作參數(shù)：① filter ② map
# 要點(diǎn)：① 語(yǔ)法糖，用來(lái)創(chuàng)建函數(shù)對(duì)象 ② 表達(dá)式不要太復(fù)雜f = lambda x :x*2f(3)6f = lambda x : True if x > 8 else False # 在if前面的是要返回的值f(3)Falsef(9)Truef = lambda x, y : x + yf(8,9)17users = [('coop', 23), ('lilei', 26), ('hmm', 15), ('zhangsan', 40)]users.sort(key=lambda x: (x[0],x[1])) # sort中有參數(shù)key，按照key的值進(jìn)行排序，以x[0]
# 的值為key # 按照字母順序排序x[0]指出了是coop,lilei,hmm等users[('coop', 23), ('hmm', 15), ('lilei', 26), ('zhangsan', 40)]users.sort(key=lambda x:(x[1],x[0])) # 按數(shù)字大小排序users[('hmm', 15), ('coop', 23), ('lilei', 26), ('zhangsan', 40)]from collections import defaultdictd = defaultdict(lambda :0) # 默認(rèn)賦值 等同于defaultdict(lambda:int)
只寫出key，而沒有指定value，默認(rèn)從int中取值，即0，而不限與0d['a']0ddefaultdict(()>, {'a': 0}) d['b']0ddefaultdict(()>, {'a': 0, 'b': 0}) d['c'] = 'coop'ddefaultdict(()>, {'a': 0, 'b': 0, 'c': 'coop'}) city = defaultdict(lambda : 'bj')citydefaultdict(()>, {}) city['shanghai']'bj'citydefaultdict(()>, {'shanghai': 'bj'}) city['coop']'bj'citydefaultdict(()>, {'shanghai': 'bj', 'coop': 'bj'}) point = defaultdict(lambda : (0, 0))point[1](0, 0)point[0](0, 0)point['pp'] = (1,2)pointdefaultdict(()>,
{1: (0, 0), 0: (0, 0), 'pp': (1, 2)}) 有些代碼----一行搞定
# all(iterable) Return True if all elements of the iterable are true (or if the iterable is empty). 都是真
# any(iterable)Return True if any element of the iterable is true. If the iterable is empty, return False 任意
# min
# max
# sum
# reversed
# sorted
# zip # 對(duì)應(yīng)合并
# []列表 列表推到是
# ()生成器 生成器
# {k, v} 字典推倒
# set/{} 去重
# if 三元操作符 xx if x else y
# enumerate 返回枚舉，帶索引m = [1,2,3,0]
all(m) # 可能是函數(shù)等
"""Signature: all(iterable, /)
Docstring:
Return True if bool(x) is True for all values x in the iterable
括號(hào)里面必須是可迭代的對(duì)象，如果可迭代對(duì)象里面的每一個(gè)都是True，則返回True
"""Falsem = [1,2,3,4,5]
all(m)Truedef f1():
return True
def f2():
return False
def f3():
return Trueall([f1(), f2(), f3()]) # [],可迭代的對(duì)象False# anyany([f1(), f2(), f3()])Truem[1, 2, 3, 4, 5]min(m)1max(m)5sum(m)
"""Signature: sum(iterable, start=0, /)
Docstring:
Return the sum of a 'start' value (default: 0) plus an iterable of numbers
""""Signature: sum(iterable, start=0, /)\nDocstring:\nReturn the sum of a 'start' value (default: 0) plus an iterable of numbers\n"sum(m)15reversed(m)
"""Init signature: reversed(self, /, *args, **kwargs)
Docstring:
reversed(sequence) -> reverse iterator over values of the sequence
Return a reverse iterator"""'Init signature: reversed(self, /, *args, **kwargs)\nDocstring: \nreversed(sequence) -> reverse iterator over values of the sequence\n\nReturn a reverse iterator'reversed(m)for i in reversed(m):
print(i)5
4
3
2
1[i for i in reversed(m)][5, 4, 3, 2, 1][i for i in reversed(range(8))][7, 6, 5, 4, 3, 2, 1, 0]m
[1, 2, 3, 4, 5]m = [2,3,90,5,4,34,22,55]
m.sort()m[2, 3, 4, 5, 22, 34, 55, 90]m = [2,3,90,5,4,34,22,55]sorted(m)[2, 3, 4, 5, 22, 34, 55, 90]sorted?
"""Signature: sorted(iterable, /, *, key=None, reverse=False)
Docstring:
Return a new list containing all items from the iterable in ascending order.
A custom key function can be supplied to customize the sort order, and the
reverse flag can be set to request the result in descending order.
Type: builtin_function_or_method"""m[2, 3, 90, 5, 4, 34, 22, 55]sorted(m, reverse=False)[2, 3, 4, 5, 22, 34, 55, 90]sorted(m, reverse=True)[90, 55, 34, 22, 5, 4, 3, 2]m1 = [-9,-3,-5,-7,3,4,6]sorted(m1)[-9, -7, -5, -3, 3, 4, 6]sorted(m1, key = abs)[-3, 3, 4, -5, 6, -7, -9]zip?
"""Init signature: zip(self, /, *args, **kwargs)
Docstring:
zip(iter1 [,iter2 [...]]) --> zip object
Return a zip object whose .__next__() method returns a tuple where
the i-th element comes from the i-th iterable argument. The .__next__()
method continues until the shortest iterable in the argument sequence
is exhausted and then it raises StopIteration."""x = [1,2,4,5,6,7,8]y = ['q','b','c','d','e']zip(x,y)print(zip(x,y))print(list(zip(x,y)))[(1, 'q'), (2, 'b'), (4, 'c'), (5, 'd'), (6, 'e')]print(dict(zip(x,y))){1: 'q', 2: 'b', 4: 'c', 5: 'd', 6: 'e'}name = ['coop','hmm','lilei']
city = ['beijing','shanghai','shenzhen']dict(zip(name,city)){'coop': 'beijing', 'hmm': 'shanghai', 'lilei': 'shenzhen'}# 列表推導(dǎo)式
[i for i in range(10)][0, 1, 2, 3, 4, 5, 6, 7, 8, 9][i^2 for i in range(10)][2, 3, 0, 1, 6, 7, 4, 5, 10, 11]# 生成器表達(dá)式()
(x**3 for i in range(8)) at 0x0000012FCD4B73B8> for y in (x**3 for x in range(8)):
print(y)0
1
8
27
64
125
216
343# 字典推導(dǎo)式
info = dict(zip(name, city))info{'coop': 'beijing', 'hmm': 'shanghai', 'lilei': 'shenzhen'}info_new = {}
for k, v in info.items():
info_new[k] = v.upper()
print(info_new){'coop': 'BEIJING', 'hmm': 'SHANGHAI', 'lilei': 'SHENZHEN'}{k:v.upper() for k, v in info.items()} # 與上面同樣的效果{'coop': 'BEIJING', 'hmm': 'SHANGHAI', 'lilei': 'SHENZHEN'}# 去重set
s = [1,1,2,3,4,5,4,5,64,6,4,3,6]
set(s){1, 2, 3, 4, 5, 6, 64}s[1, 1, 2, 3, 4, 5, 4, 5, 64, 6, 4, 3, 6]list(set(s))[64, 1, 2, 3, 4, 5, 6]三元操作符
if True:
pass
else:
passTrue if s =='a' else FalseFalses[1, 1, 2, 3, 4, 5, 4, 5, 64, 6, 4, 3, 6]s = 'a'True if s =='a' else False True分享題目：IteratorandGenerator-2
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