什么是Python中的匿名函数

salaries={
  'egon':3000,
  'alex':100000000,
  'wupeiqi':10000,
  'yuanhao':2000
}
def get(k):
  return salaries[k]
print(max(salaries,key=get)) #'alex' 
print(max(salaries,key=lambda x:salaries[x]))
info = [
  {'name': 'egon', 'age': '18', 'salary': '3000'},
  {'name': 'wxx', 'age': '28', 'salary': '1000'},
  {'name': 'lxx', 'age': '38', 'salary': '2000'}
]
max(info, key=lambda dic: int(dic['salary']))
max([11, 22, 33, 44, 55])

salaries={
  'egon':3000,
  'alex':100000000,
  'wupeiqi':10000,
  'yuanhao':2000
}
print(min(salaries,key=lambda x:salaries[x]))  # 'yuanhao' 
 info=[
      {'name':'egon','age':'18','salary':'3000'},
      {'name':'wxx','age':'28','salary':'1000'},
      {'name':'lxx','age':'38','salary':'2000'}
    ]
min(info,key=lambda dic:int(dic['salary']))

salaries={
  'egon':3000,
  'alex':100000000,
  'wupeiqi':10000,
  'yuanhao':2000
}
alaries=sorted(salaries) # 默认按照字典的键排序
print(salaries)
# salaries=sorted(salaries,key=lambda x:salaries[x]) #默认是升序排
alaries=sorted(salaries,key=lambda x:salaries[x],reverse=True) #降序
print(salaries)
info=[
      {'name':'egon','age':'18','salary':'3000'},
      {'name':'wxx','age':'28','salary':'1000'},
      {'name':'lxx','age':'38','salary':'2000'}
    ]
l=sorted(info,key=lambda dic:int(dic['salary']))

v1 = [11,22,33,44]
result = map(lambda x:x+100,v1) # 第一个参数为执行的函数,第二个参数为可迭代元素.
print(list(result)) # [111,122,133,144]
names=['alex','wupeiqi','yuanhao','egon']
res=map(lambda x:x+'_NB' if x == 'egon' else x + '_SB',names)
print(list(res))

import functools
v1 = ['wo','hao','e']
def func(x,y):
  return x+y
result = functools.reduce(func,v1) 
print(result)  # wohaoe
result = functools.reduce(lambda x,y:x+y,v1)
print(result)  # wohaoe
from functools import reduce
l=['my','name','is','alex','alex','is','sb']
res=reduce(lambda x,y:x+' '+y+' ',l)
print(res)
#my name is alex alex is sb

result=filter(lambda x:x > 2,[1,2,3,4])
print(list(result))
v1 = [11,22,33,'asd',44,'xf']
# 一般做法
def func(x):
  if type(x) == int:
    return True
  return False
result = filter(func,v1)
print(list(result))   # [11,22,33,44]
# 简化做法
result = filter(lambda x: True if type(x) == int else False ,v1)
print(list(result))
# 极简做法
result = filter(lambda x: type(x) == int ,v1)
print(list(result))
names=['alex_sb','wxx_sb','yxx_sb','egon']
res=filter(lambda x:True if x.endswith('sb') else False,names)
res=filter(lambda x:x.endswith('sb'),names)
print(list(res))    #['alex_sb', 'wxx_sb', 'yxx_sb']
ages=[18,19,10,23,99,30]
res=filter(lambda n:n >= 30,ages)
print(list(res))    #[99, 30]
salaries={
  'egon':3000,
  'alex':100000000,
  'wupeiqi':10000,
  'yuanhao':2000
}
res=filter(lambda k:salaries[k] >= 10000,salaries)
print(list(res))      #['alex', 'wupeiqi']