[py]可迭代对象-求最值

for .. in ..方式遍历可迭代对象

而非下标

## 判断是否可迭代
from collections import Iterable
print(isinstance(123,Iterable))
print(isinstance('abc',Iterable))
print(isinstance([],Iterable))
print(isinstance({},Iterable))


## 打印str下标和值
for k,v in enumerate('abc'):
    print(k,v)
print('------------')
for k,v in enumerate({'a':1,'b':2}):
    print(k,v)

• 求arr的最大值
• 求arr的最大的2个值
• 求arr的max和min

# 求arr的最大值

arr = [11,2,3]
max_num = 0
for i in arr:
    if i > max_num:
        max_num = i
print(max_num)


# 找出arr最大的两个值
## 思路,找2个游标,看i落在哪里了.

max_num = 0
sec_num = 0
arr = [1, 2, 2, 3]

for i in arr:
    if i < sec_num:
        sec_num = i
    elif i > sec_num and i < max_num:
        sec_num = i
    elif i > max_num:
        sec_num = max_num
        max_num = i

print(sec_num, max_num)


# 找出最大最小值
# 迭代查找一个list中最小和最大值，并返回一个tuple
arr = [1, 2, 1, 3, 4, 5]


def get_min_max(arr):
    max_num = arr[0]
    min_num = arr[0]
    if len(arr) == 0:
        return ""
    for i in arr:
        if i < min_num:
            min_num = i
        if i > max_num:
            max_num = i
    print(min_num, max_num)
    return (min_num, max_num)


get_min_max(arr)