为什么包含一个简单的while循环的for循环只运行两次？也很糟糕
我尝试在这个while循环上循环几次，以收集有关输出正确的行序列所需时间的信息(拼写为“编码器”)。我预计我的for循环会循环十次。相反，我只得到了一次循环，然后在0秒内完成了一次故障重复。
我可以用while i < 10替换for i in (0, 10)行，然后添加一个i += 1，以获得更长的故障输出(它将把第一个结论循环到while循环n次，而不是2次)。我还尝试在for循环中移动列表和字典，但这并不能使循环正常运行。
from random import randint
from time import sleep
import datetime
stats_collection = []
correct_order = [0, 1, 2, 3, 4] # A list of numbers between 0 and 4
output_order = []
iterations = 0
the_lines = {0: "...###.................#####...####..",
1: "..#...#.........####...#.......#...#.",
2: "..#.......###...#...#..##......##....",
3: "..#...#..#...#..#...#..#.......#.#...",
4: "...###....###...####...#####...#..#..",}
for i in (0,10):
a_currentDT = str(datetime.datetime.now())
while output_order[-5:] != correct_order:
next = randint(0, 4) # Select between
output_order.append(next)
print(the_lines[next])
iterations += 1
# sleep(0.125)
final_iterations = iterations
b_currentDT = str(datetime.datetime.now())
print("Finished!")
print("Iterations: {num}".format(num=final_iterations))
print(a_currentDT)
print(b_currentDT)
stats_collection.append(final_iterations)
print(stats_collection)我所期望的是来自print(stats_collection)的打印列表，类似于：[134, 2948, 4001, 598, 910, 1000, 2000, 3003, 10593, 403]或另一组10个数字。但是我只打印第一次运行两次，或者如果我用一个n循环替换for循环(就像在while i < 10或其他什么地方)，就会打印while次。
下面是我从for i in (0, 10):得到的输出，作为在while循环上循环的机制：
Finished!
Iterations: 8598
2019-06-02 15:21:21.543503
2019-06-02 15:21:21.641444
Finished!
Iterations: 8598
2019-06-02 15:21:21.641444
2019-06-02 15:21:21.641444
[8598, 8598]我期望代码再次运行while循环，并得到一个完全不同的结果，包括总共10个不同的结果，如下所示：
Finished!
Iterations: 8598
2019-06-02 15:21:21.543503
2019-06-02 15:21:21.641444
Finished!
Iterations: 159
2019-06-02 15:21:21.641445
2019-06-02 15:21:21.700555
[8598, 159]但当然有十种不同的结果。
除了这个杂项错误之外，代码可以很好地工作。我真的不明白为什么代码要这么做。
看到第二个循环实际上是瞬间完成的，这可能是有用的。我根本不知道发生了什么事。我不能像那样在for循环中托管一个while循环吗？
回答 2
Stack Overflow用户
发布于 2019-06-03 07:56:08
您的while循环有1/ 3125的机会在每次迭代中产生适当的顺序。大约需要2000次迭代才有50%的机会找到合适的顺序。5000次迭代将有80%的机会找到它。这应该会提供随机的执行时间，但是，由于您的代码现在很紧凑，它只会一遍又一遍地重复第一个结果。
边走边打印行会大大减慢速度。
由于您没有重置样本之间的output_order，因此您的第二次遍历将立即找到匹配结果(如时间所示)，但将显示之前的迭代次数，因为您也没有重置该变量。
Stack Overflow用户
发布于 2019-06-03 07:58:40
我对您的代码做了一些修改，因为您似乎执行了很多不必要的重复。根据我对你的规范的理解，你想计算一下拼写编码器需要重复多少次。我更改了代码，使其只在随机整数与要打印的当前行的索引匹配时才移动到下一行。
`from random import randint
from time import sleep
import datetime
stats_collection = []
correct_order = [0, 1, 2, 3, 4] # A list of numbers between 0 and 4
iterations = 0
the_lines = {0: "...###.................#####...####..",
1: "..#...#.........####...#.......#...#.",
2: "..#.......###...#...#..##......##....",
3: "..#...#..#...#..#...#..#.......#.#...",
4: "...###....###...####...#####...#..#..",}
for i in range(0,10):
output_order = [None for i in range(len(correct_order))]
a_currentDT = str(datetime.datetime.now())
idx = 0
while output_order != correct_order:
next = randint(0, 4) # Select between
if output_order[idx] == None and idx == next:
output_order[idx] = next
idx += 1
print(the_lines[next])
iterations += 1
# sleep(0.125)
print(output_order)
final_iterations = iterations
b_currentDT = str(datetime.datetime.now())
print("Finished!")
print("Iterations: {num}".format(num=final_iterations))
print(a_currentDT)
print(b_currentDT)
stats_collection.append(final_iterations)
iterations = 0
print(stats_collection)`我也有一个修改，最接近匹配你在一开始。
`from random import randint
from time import sleep
import datetime
stats_collection = []
correct_order = [0, 1, 2, 3, 4] # A list of numbers between 0 and 4
iterations = 0
the_lines = {0: "...###.................#####...####..",
1: "..#...#.........####...#.......#...#.",
2: "..#.......###...#...#..##......##....",
3: "..#...#..#...#..#...#..#.......#.#...",
4: "...###....###...####...#####...#..#..",}
for i in range(0,10):
output_order = []
a_currentDT = str(datetime.datetime.now())
while output_order[-5:] != correct_order:
next = randint(0, 4) # Select between
output_order.append(next)
iterations += 1
# print(the_lines[next])
# sleep(0.125)
# print(output_order[-5:])
final_iterations = iterations
b_currentDT = str(datetime.datetime.now())
print("Finished!")
print("Iterations: {num}".format(num=final_iterations))
print(a_currentDT)
print(b_currentDT)
stats_collection.append(final_iterations)
iterations = 0
print(stats_collection)`https://stackoverflow.com/questions/56419454
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