Python-day 14三目演算、導出式、再帰、匿名、内蔵関数
28488 ワード
一、三項演算子
二、導出式
三、再帰
四、匿名関数
五、内蔵関数
転載先:https://www.cnblogs.com/zhouqinmei/p/10656587.html
: if...else...
: if...else... ,
:
cmd = input('cmd: ')
print(' ') if cmd.isdigit() else print(' ')
a = 20
b = 30
res = a if a > b else b #
print(res)
res = 'b ' if a > b else 'a ' #
print(res)
a=20
b=30
res=a if a>b else b
print(res)
res='b 'if a>b else 'a ' #
print(res)
: , : a
二、導出式
:[v for v in iterable]
dic = {
'a': 1, 'b': 2, 'c': 3} # => [('a', 1), ('b', 2), ('c', 3)]
res = [(k, v) for k, v in dic.items()]
:{k: v fro k, v in iterable}
ls = [('a', 1), ('b', 2), ('c', 3)] # => {'a': 1, 'b': 2, 'c': 3}
res = {k: v for k, v in ls}
dic={
'a':1,'b':2,'c':3} # [('a',1),('b',2),('c',3)]
res=[(k,v)for k,v in dic.items()]
print(res) # [('a',1),('b',2),('c',3)]
print('=================================')
res=((k,v)for k,v in dic.items())
print(tuple(res)) # :(('a', 1), ('b', 2), ('c', 3))
ls=[('a',1),('b',2),('c',3)] # >>>{'a':1,'b',2,'c:3'}
res={k:v for k,v in ls }
print(res) # {'a': 1, 'b': 2, 'c': 3}
rang(10)
res_ls=[arg for arg in range(10)]
print(res_ls) # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
res_dic={
'a':arg for arg in range(10)}
print(res_dic) # {'a': 9}
res_dic={arg:'a' for arg in range(10)}
print(res_dic) # {0: 'a', 1: 'a', 2: 'a', 3: 'a', 4: 'a', 5: 'a', 6: 'a', 7: 'a', 8: 'a', 9: 'a'}
res_dic={v:k for k,v in enumerate('abc')}
print(res_dic)
# {'a': 0, 'b': 1, 'c': 2}
三、再帰
:
: ,
: ( 、 )
: ( )
:
:
import sys
sys.setrecursionlimit(100) # ( )
print(sys.getrecursionlimit())
count=0
def a():
global count
count+=1
if count>50:
return
a()
a()
: ,
def b():
c()
def c():
d()
def d():
b()
b()
:
, , ,
:
def get_age(num): #
if num==1:
return 58
age=get_age(num-1)-2
return age
res=get_age(5)
print(res)
def factorial(num):
if num==1:
return 1
temp=num*factorial(num-1)# >>>> 5*4*3*3*1
return temp
res=factorial(5)
print(res)
# 5 !=5*4! 4!=4*3!......2!=2*1
四、匿名関数
:
,
lambda | ()| return
lambda x,y:x+y
f=lambda x,y:x+y
print(f)
print(f(10,20)) # 30
f=lambda x,y:(x+y,x-y) # (x+y,x-y)
print(f)
print(f(10,20)) # (30 ,-10)
:
1、 , ,
2、 : , ,
res=(10,20,50,30)
print(res)
res=max({10,20,50,30})
print(res)
print('====================================')
def fn(arg):
print(arg)
return arg
ls =[100,200,50,10]
res=max(ls,key=fn)
print(res) # :100 200
print('====================================')
res1=max(ls,key=lambda ele:ele)
print(res1)
# 200
五、内蔵関数
# max
iterable = [1, 5, 3, 2, 7]
res = max(iterable, key=lambda x: x) # : ; :
print(res)
#
iterable = {
'Bob': 12000,
'Tom': 37000,
'Jerry': 76000,
'Zero': 120,
}
res = max(iterable, key=lambda x: iterable[x]) # x: k :
print(res)
iterable = {
'Bob': {
'no': 100, 'salary': 12000},
'Tom': {
'no': 200, 'salary': 37000},
'Jerry': {
'no': 50, 'salary': 76000},
'Zero': {
'no': 150, 'salary': 120},
}
res = max(iterable, key=lambda k: iterable[k]['no'])
print(res)
res = max(iterable, key=lambda k: iterable[k]['salary'])
print(res)
# min
iterable = {
'Bob': [100, 12000],
'Tom': [200, 37000],
'Jerry': [50, 76000],
'Zero': [150, 120],
}
res = min(iterable, key=lambda k: iterable[k][1]) #
print(res)
# sorted
res = sorted([1, 3, 4, 2, 5], key=lambda x: x, reverse=True)
print(res)
iterable = {
'Bob': [100, 12000],
'Tom': [200, 37000],
'Jerry': [50, 76000],
'Zero': [150, 120],
}
res = sorted(iterable, key=lambda x: iterable[x][0]) # no
print(res)
# map:
res = map(lambda x: x + 2, [12000, 36000, 27000, 21000, 10000])
print(list(res))
from functools import reduce
# reduce:
res = reduce(lambda f, n: f * n, [1, 2, 3, 4, 5])
print(res)
# :
# classmethod() #
# staticmenthod() #
# super()
# object()
#
# globals()
# locals()
#
# getattr()
# setattr()
# delattr()
# <=>
# exec()
# enumerate()
# isintance()
# len()
# max()
# min()
# open()
# range()
# type()
print('-----------------------------------')
#
print(abs(-1)) #
print(pow(2, 3, 3)) # 2 ** 3 % 3
print(sum([1, 2, 3])) #
print(divmod(100, 30)) # 100 30
#
print(all([1, 2, 'abc'])) #
print(any([1, "", None])) #
filter(lambda x: x % 2 == 0, [1, 2, 3, 4, 5]) #
#
print(ascii('
-*..'))
print(repr('
-*..'))
print(r'
-*..')
#
print(10)
print(bin(10))
print(oct(10))
print(hex(10))
#
bool()
str()
bytes()
chr()
ord()
range(1, 5) # [1, 2, 3, 4]
'''
def aaa():pass
print(callable(aaa)) #
# '' ,
s = 'print(123)'
# print(s)
eval(s)
s = '{"a": 1}'
res = eval(s)
print(res['a'])
res = divmod(100, 30) # 100 30
print(res)
res = filter(lambda x: x % 2 == 0, [1, 2, 3, 4, 5])
print(list(res))
#
res = format(97, 'b')
print(res)
#
print(globals())
def a():
a = 10
b = 20
print(locals())
a()
# hash
# print(hash([])) # hash
# print(hash(())) # hash
# import uuid
# print(uuid.uuid4())
open()
range()
t = max(iter, fn) max(iter lambda k: i[k])
temp = None
for k in iter:
res = fn(k)
# res
# temp res
return temp
転載先:https://www.cnblogs.com/zhouqinmei/p/10656587.html