Python高阶函数

一张思维导图带你学习Python高阶函数，知识点有常用实参高阶函数、map（函数、序列）、reduce等。

实参高阶函数

• 常用实参高阶函数
  • max
    • 子主题
      • # 练习1：获取nums中个位数字最大的元素nums = [29, 73, 64, 301, 68, 55, 76]print(max(nums, key=lambda item: item % 10))print(min(nums, key=lambda item: item % 10))print(sorted(nums, key=lambda item: item % 10))
      • # 练习2：获取nums中各个个位数之和最大的元素nums = [29, 73, 64, 31, 68, 55, 76]# print(max(nums, key=lambda item:item//10 + item%10))print(max(nums, key=lambda item: sum([int(x) for x in str(item)])))
      • # 练习3：获取nums中绝对值最大的元素nums = [29, 73, 64, -31, 68, 55, -76]print(max(nums, key=lambda item: item if item > 0 else -item))
      • # 练习4：获取points中y坐标最大的元素points = [(19, 2), (0, 18), (3, 4)]print(max(points, key=lambda item: item[-1]))
  • min
  • sorted
    • sorted
• map(函数,序列)
  • map(函数,序列1,序列2)
    • nums = [29, 73, 64, 31, 68, 55, 76]# [9, 3, 4, 1, 8, 5, 6]result = list(map(lambda item: item % 10, nums))print(result)
  • map(函数,序列1,序列2,序列3)
    • nums1 = [238, 89, 78, 23]nums2 = [92, 78, 61, 44]# [82, 98, 81, 34]result = list(map(lambda item1, item2: item1 % 10 * 10 + item2 % 10, nums1,nums2))print(result)———
  • map(函数,序列1,序列2,序列3,...)
    • # 练习5list1 = ['python', 'java', 'h5']list2 = [22, 21, 19]list3 = [2, 9, 18]# ['python2202', 'java2109', 'h51918']result = list(map(lambda item1,item2,item3:f'{item1}{item2}{item3:0>2}', list1, list2, list3))print(result)
• reduce
  • reduce(函数,序列,初始值)
    • 初始值：一般是0、1或者空串
  • 注意：使用reduce之前必须先从functools中导入
  • from functools import reducenums = [10, 23, 4, 8]result = reduce(lambda x, item: x+item, nums, 0)print(result)#求所有元素的和 10+23+4+8
  • nums = [10, 23, 4, 8]# 求所有元素的乘积: 10x23x4x8result = reduce(lambda x, item: x * item, nums, 1)print(result)
  • students = [ {'name': 'stu1', 'age': 19, 'score': 72}, {'name': 'stu2', 'age': 22, 'score': 89}, {'name': 'stu3', 'age': 30, 'score': 60}, {'name': 'stu4', 'age': 17, 'score': 77}]# 求总分数result = reduce(lambda x, item: x + item['score'], students, 0)print(result)