Python中map,reduce,filter和sorted函数的使用方法

map(funcname, list)

def sq(x):
  return x*x #求x的平方
map(sq, [1,3, 5,7,9]) #[1, 9, 25, 49, 81]

map(str, [23,43,4545,324]) #['23', '43', '4545', '324']

map(sq, (1,3, 5,7,9)) # tuple [1, 9, 25, 49, 81]
map(sq, set([1,3, 5,3,7,9])) # set [1, 9, 81, 25, 49]

 {"name": "Yi_Zhi_Yu", "age":25}

{"Yi_Zhi_Yu", 25}

set(["Yi_Zhi_Yu", 25])# 你会看到最终的输出形式是{25, 'Yi_Zhi_Yu'}

  {1,3, 5, 3, 7, 9} #{1, 3, 5, 7, 9}

reduce(funcname, list)

def c_sum(x, y):
  return x + y;
reduce(c_sum, range(1,101)) #5050

filter(funcname, list)

 def is_int(x):
  if isinstance(x, (int)):
    return True
  else:
    return False

 filter(is_int, ["Yi",2, "3", 4]) #[2, 4]

sorted

sorted( list, [comp_func])

sorted([3,4, 12, 5, 9, 1]) #[1, 3, 4, 5, 9, 12]

 def m_order(x, y):
  if(x > y):
    return -1
  elif(x == y):
    return 0
  else:
    return 1
sorted([3,4, 12, 5, 9, 1], m_order) #[12, 9, 5, 4, 3, 1]