python语法系列

1. list comprehension

reference:https://realpython.com/list-comprehension-python/

# new_list = [expression for member in iterable if conditional]

matrix=[
		 [0,0,0],
		 [1,1,1],
		 [2,2,2]
]
# 注意先迭代行，comprehension从左至右
a = [number for row in matrix for number in row]
print(a)


Expression	Purpose	Output
[number for row in matrix for number in row]	Flattens matrix	Single list containing all elements in row-major order
[number for number in row for row in matrix]	Likely error	Error due to attempting to iterate over undefined elements

2. generator

# now python3 can store a huge number only limited to the memory instead of the system architecture, the integer in python3 can grow dynamically, sys.maxsize represent the maxint in python based on the system's architecture
a=sum(number * number for number in range(1_000_000_000))

3.unpack

print(*range(0,16,8)