有效地连接大列表元素(Concatenate Big List Elements Efficiently)

 我想列出一个元素列表，其中每个元素以4个数字开头，每个元素以4个字母结尾。 这是我的代码 
 
import itertools

def char_range(c1, c2):
    """Generates the characters from `c1` to `c2`"""
    for c in range(ord(c1), ord(c2)+1):
        yield chr(c)


chars =list()
nums =list()
for combination in itertools.product(char_range('a','b'),repeat=4):
        chars.append(''.join(map(str, combination)))

for combination in itertools.product(range(10),repeat=4):
        nums.append(''.join(map(str, combination)))

c = [str(x)+y for x,y in itertools.product(nums,chars)]
for dd in c:
        print(dd)
 
 这样运行正常但是当我使用更大范围的字符（例如（az））时，程序会占用CPU和内存，并且PC变得没有响应。 那么我怎么能以更有效的方式做到这一点呢？ 

I want to make a list of elements where each element starts with 4 numbers and ends with 4 letters with every possible combination. This is my code
 
import itertools

def char_range(c1, c2):
    """Generates the characters from `c1` to `c2`"""
    for c in range(ord(c1), ord(c2)+1):
        yield chr(c)


chars =list()
nums =list()
for combination in itertools.product(char_range('a','b'),repeat=4):
        chars.append(''.join(map(str, combination)))

for combination in itertools.product(range(10),repeat=4):
        nums.append(''.join(map(str, combination)))

c = [str(x)+y for x,y in itertools.product(nums,chars)]
for dd in c:
        print(dd)
 
This runs fine but when I use a bigger range of characters, such as (a-z) the program hogs the CPU and memory, and the PC becomes unresponsive. So how can I do this in a more efficient way?

原文：https://stackoverflow.com/questions/47971684