递归调用: 在调用一个函数的过程中, 直接或者间接又调用了函数本身, 称之为递归调用.
递归的必备的两阶段: 一: 递推 二: 回溯
- def foo():
- print('abc')
- foo()
- foo()
- import sys
- print(sys.getrecursionlimit())
- sys.getrecursionlimit(200) #设置递归次数
- print(sys.getrecursionlimit())
- def age(n):
- if n == 1:
- return 18
- return age(n-1) + 2
- print(age(5))
- g=[1,[2,[3,[4,[5,[6,[7]]]]]]]
- def foo(g):
- for i in g:
- if type(i) is list:
- foo(g)
- else:
- print(i)
- foo(g)
二分法:
- g=[1,2,3,4,5,6,7,8,10,13,455,678,990,11111] #从小到大排列的数字列表
- def foo(g,numl):
- print(g)
- if len(g) == 0:
- print("it is not")
- return
- fdoml=len(g) // 2
- if numl> g[fdoml]:
- foo(g[fdoml+1:],numl)
- elif numl < g[fdoml]:
- foo(g[0:fdoml],numl)
- else:
- print('find it')
- foo(g,678)
- #zip 拉链函数
- g='wordwrod'
- h=[1,2,3,4]
- f=zip(g,h)
- print(list(f))
匿名函数: lambda 没有函数调用名称, 只生成一次存在于内存地址.
- def foo(x,y):
- return x+y
- foo(1,2)
同:
print(lambda x,y:x+y)(1,2)
匿名函数的使用:
- #max 最大
- sab={
- 'a':1223
- 'b':12345
- 'c':34567
- 'd':345
- }
- def foo(k):
- return sab[k]
- print(max(sab,key=foo))
同:
- print(max(sab,key=lambda k:sab[k]))
- #min 最小
- print(min(sab,key=lambda k:sab[k]))
- #sorted 排序, 默认按照首字母排序
- sab={
- 'a':1223
- 'b':12345
- 'c':34567
- 'd':345
- }
- print(sorted(sab,key=lambda k:sab[k],reverae=Ture)) #reverae=Ture 反转
- #map 映射
- names=['df','gh','jk']
- u=[]
- for i in names:
- res='%s_bb' %names
- u.append(res)
- print(u)
同:
- g=map(lambda i:'%s_bb' %i,names)
- print(list(g))
- #reduce 合并
- from functcols import reduce
- reduce(lambda x,y:x+y ,range(1,101))
- reduce(lambda x,y:x+y ,range(1,101),100) #设定初始值, 100 为初始值
- #filter 过滤
- names=['df_bb','gh_bb','jk_bb']
- g=filter(lambda x:x.endswith('bb'),names)
- print(list(g))
来源: http://www.bubuko.com/infodetail-2742191.html