我有这个程序，计算回答特定问题所花费的时间，并在答案不正确时退出while循环，但我想删除最后的计算，所以我可以调用min()，这不是错误的时间，抱歉，如果这是令人困惑的。
from time import time
q = input('What do you want to type? ')
a = ' '
record = []
while a != '':
start = time()
a = input('Type: ')
end = time()
v = end-start
record.append(v)
if a == q:
print('Time taken to type name: {:.2f}'.format(v))
else:
break
for i in record:
print('{:.2f} seconds.'.format(i))
当前回答
如果你做了很多时间，我可以推荐这个小(20行)上下文管理器:
https://github.com/brouberol/timer-context-manager
你的代码可以是这样的:
#!/usr/bin/env python
# coding: utf-8
from timer import Timer
if __name__ == '__main__':
a, record = None, []
while not a == '':
with Timer() as t: # everything in the block will be timed
a = input('Type: ')
record.append(t.elapsed_s)
# drop the last item (makes a copy of the list):
record = record[:-1]
# or just delete it:
# del record[-1]
仅供参考，以下是定时器上下文管理器的完整内容:
from timeit import default_timer
class Timer(object):
""" A timer as a context manager. """
def __init__(self):
self.timer = default_timer
# measures wall clock time, not CPU time!
# On Unix systems, it corresponds to time.time
# On Windows systems, it corresponds to time.clock
def __enter__(self):
self.start = self.timer() # measure start time
return self
def __exit__(self, exc_type, exc_value, exc_traceback):
self.end = self.timer() # measure end time
self.elapsed_s = self.end - self.start # elapsed time, in seconds
self.elapsed_ms = self.elapsed_s * 1000 # elapsed time, in milliseconds
其他回答
你应该用这个
del record[-1]
问题在于
record = record[:-1]
是不是每次你删除一个项目时，它都会复制一份列表，所以不是很有效
必须使用*list，_ = list，如下例所示
record = [1,2,3]
*record,_ = record
record
---
[1, 2]
如果你做了很多时间，我可以推荐这个小(20行)上下文管理器:
https://github.com/brouberol/timer-context-manager
你的代码可以是这样的:
#!/usr/bin/env python
# coding: utf-8
from timer import Timer
if __name__ == '__main__':
a, record = None, []
while not a == '':
with Timer() as t: # everything in the block will be timed
a = input('Type: ')
record.append(t.elapsed_s)
# drop the last item (makes a copy of the list):
record = record[:-1]
# or just delete it:
# del record[-1]
仅供参考，以下是定时器上下文管理器的完整内容:
from timeit import default_timer
class Timer(object):
""" A timer as a context manager. """
def __init__(self):
self.timer = default_timer
# measures wall clock time, not CPU time!
# On Unix systems, it corresponds to time.time
# On Windows systems, it corresponds to time.clock
def __enter__(self):
self.start = self.timer() # measure start time
return self
def __exit__(self, exc_type, exc_value, exc_traceback):
self.end = self.timer() # measure end time
self.elapsed_s = self.end - self.start # elapsed time, in seconds
self.elapsed_ms = self.elapsed_s * 1000 # elapsed time, in milliseconds
只需简单地使用list.pop() 现在，如果你想以另一种方式使用:list.popleft()
如果我理解正确，你可以使用切片符号来保留除最后一项以外的所有内容:
record = record[:-1]
但更好的方法是直接删除该项:
del record[-1]
注意1:注意使用record = record[:-1]并不真正删除最后一个元素，而是将子列表分配给record。如果您在函数中运行它，而record是一个参数，则会产生不同。使用record = record[:-1]，原始列表(在函数之外)不变，使用del record[-1]或record.pop()，列表被改变。(正如@pltrdy在评论中所说)
注2:代码可以使用一些Python习语。我强烈推荐大家读读这篇文章: 像Pythonista一样编写代码:地道的Python(通过wayback machine存档)。
