Python内部循环和外部循环与计数器迭代列表

Question

我有一个特定的问题，我试图在内部循环(执行3次)上找到解决方案，并继续在for循环中处理列表的其余部分:

strings = ['A','A','A','A','A','A','A','A','A','A','B','B','B','B','B','B','B','B','B','B',
'A','A','A','A','A','A','A','A','A','A','B','B','B','B','B','B','B','B','B','B']
i=0
for string in strings:
global i
if string == 'A':
while i < 3:
print(string, i)
i+=1
if i==3: continue
elif string== 'B':
while i < 3:
print(string,i)
i+=1
if i==3: continue
#         print(string)

当前结果:一个0一个12

期望在内部循环完成后继续遍历列表，并从下一个开始处理:

A 0
A 1
A 2
B 0
B 1
B 2
A 0
A 1
A 2
B 0
B 1
B 2

Answer 1

如果我正确理解逻辑，您可以使用itertools.groupby来帮助您形成组:

变体# 1

from itertools import groupby
MAX = 3
for k,g in groupby(strings):
for i in range(min(len(list(g)), MAX)):
print(f'{k} {i}')
print()

变体# 2

from itertools import groupby
MAX = 3
for k,g in groupby(strings):
for i,_ in enumerate(g):
if i >= MAX:
break
print(f'{k} {i}')
print()

输出:

A 0
A 1
A 2
B 0
B 1
B 2
A 0
A 1
A 2
B 0
B 1
B 2

变量#3:without import

prev = None
count = 0
MAX = 3
for s in strings:
if s == prev:
if count < MAX:
print(f'{s} {count}')
count += 1
elif prev:
count = 0
print()
prev = s