table of Contents

Anonymous function

Famous -> with the name
Anonymous -> no name -> no way to call -> and only in combination with certain methods

Anonymous function syntax

lambda Parameters: Return Value

If you really use, it can also be used, but will become a well-known function

 f = lambda x, y: x * y
 res = f(1, 2)
 print(res)

max / min / filter / map / sorted MS

max / min returns the maximum

res = max([1, 2, 3, 4, 5])
print(res)
res = max(1, 2, 3, 4, 5, 6, )
print(res)
salary_dict = {
     'nick': 3000,
     'jason': 100000,
     'tank': 5000,
     'sean': 2000,
     'z': 1000
 }
 def func(name):  # nick/jason/tank/sean/z
     return salary_dict[name]  # 3000/100000/5000/2000/1000
 res = max(salary_dict, key=func)  # 默认key的首字母
 res = max(salary_dict, key=lambda name: salary_dict[name])  # 默认key的首字母
 print(res)

key = func default thing to do

Loop through salary_dict, will take all the key value
Then all the key values in turn thrown into func in return pay
By ordering pay returns to give maximum

res = min(salary_dict, key=lambda name: salary_dict[name])
print(res)

fileter ---> Screening

def function(item):  # 1/2/3/4
    if item < 5:
         return True
     else:
         return False
 res = filter(function, [1, 2, 3, 4])
 res = filter(lambda item: item > 2, [1, 2, 3, 4])
 print(res)  # 迭代器
 print(list(res))
 
 salary_dict = {
     'nick': 3000,
     'jason': 100000,
     'tank': 5000,
     'sean': 2000,
     'z': 1000
 }

res = filter(lambda item: salary_dict[item] > 3000, salary_dict)
  print(list(res))

map -> Mapping -> y = x + 1

 def function1(item):
     return item + 2
 res = map(function1, [1, 2, 3, ])
 print(res)
 print(list(res))

sorted -> Sort

 def function2(item):
     return salary_dict[item]
 salary_dict = {
     'nick': 3000,
     'jason': 100000,
     'tank': 5000,
     'sean': 2000,
     'z': 1000
 }

 res = sorted([2,3,4,1,0,5],key=function2,reverse=True)
 res = sorted(salary_dict, key=function2, reverse=True)
 print(list(res))

Built-in functions

 python解释器内置方法:

# bytes
res = bytes('中国', encoding='utf8')
print(res)
# chr/ord
print(chr(97))
print(ord('a'))
# divmod
print(divmod(10, 4))  # 取整/取余
# enumerate(********)
lt = [1, 2, 3]
for i in range(len(lt)):
    print(i, lt[i])

for ind, val in enumerate(lt):
    print(ind, val)

# eval(***) --> 把字符串的引号去掉,留下来的是什么就是什么

s = '"abc"'
print(type(eval(s)), eval(s))
# hash,可变不可哈希
print(hash(123123))

# 了解

# abs
print(abs(-1))
# all# 可迭代对象内的元素全部为True则为True
print(all([1, 2, 3, 3]))
# any
print(any([0, 0, ]))
# bin/oct/hex
print(bin(123))
print(oct(123))
print(hex(123))
# dir: 列出模块的所有方法
# import time
#
# print(dir(time))
# frozenset: 不可变化的集合,类似于元组
s = frozenset({1, 2, 3})
print(s)

# gloabals/locals
# print(globals())  # 列出所有全局变量
# print('locals():', locals())

def func():
    s = 's1'
    print(globals())  # 列出所有全局变量
    print('locals():', locals())  # 列出当前位置所有变量

func()
# pow
print(pow(2, 2))
# round
print(round(10.333))
# slice
s = slice(1, 5, 2)  # 1start,5stop,2step
lt = [1, 2, 3, 4, 5, 6, 7]
print(lt[s])
print(lt[1:5:2])
# # sum
print(sum([1, 2, 3, 4, 5]))
# __import__  # 通过字符串导入模块
# import 'time'

time = __import__('time')
print(time.time())

Exception Handling

Exception Handling: report a mistake, for processing

 dic = {'a': 1}
#
# try:
#
#     print(dic['b'])  # KeyError
#     1 / int(num)  # 报错之后,不运行下面的代码
#
# except Exception as e:  # 万能异常,只要有错误,就捕捉
#     print(e)  # 错误的描述信息
#     print('傻逼,不知道什么错误')
#
# print(2)



# fr = open('test.py')
# try:
#     # 文件中途报错
#     1 / 0
#     fr.close()
# except Exception as e:
#     print(e)
# finally:  # 无论你包不报错,都执行这一行
#     print('finally')

assert assert condition + -> eliminated by history

Process-oriented programming

Noodles version - "process-oriented programming -" thought - "Object-Oriented Programming

There is no good or bad idea

For (Pronoun - "Use) Process (Process -" step) programming (write code, write file)

Made of bronze

I input input (defined variables) P Process Process (control variables changing) O output (new variable) == oriented programming process programmed the output

Materials - "Liquid baking -" poured into a mold - "Cooling -" Beat - "Cooling -" outputs a Bronze

A step that is a function

Process-oriented programming: similar lines, step by step down

Pros: Very clear logic

Cons: Back wrong, wrong with the next step to follow

Why error

Logic - "control variables changing wrong direction

Check the error - "change the status of print variable -"

x = 10

y = 20

z = x + y
print(1, z) # 30

z = z + 10
print(2, z) # 40

z = z - 20

print(z)

debug

day14 summary