我在python中的以下函数有一个问题(swap是我以前创建的一个函数,工作正常):
def swap (cards):
"""
>>> swap('FBFFFBFFBF')
'BFBBBFBBFB'
>>> swap('BFFBFBFFFBFBBBFBBBBFF')
'FBBFBFBBBFBFFFBFFFFBB'
>>> swap('FFBFBFBFBFBFBFBBFBFBFBFBBFBFBBFBF')
'BBFBFBFBFBFBFBFFBFBFBFBFFBFBFFBFB'
"""
invert=""
for i in cards:
if i is "B":
invert+="F"
else:
invert+="B"
return (invert)
def swap2 (cards):
"""
>>> next('FBFFFBFFBF')
'FFBBBFBBFF'
>>> next('BFFBFBFFFBFBBBFBBBBFF')
'FBBFBFBBBFBFFFBFFFFFF'
>>> next('FFBFBFBFBFBFBFBBFBFBFBFBBFBFBBFBF')
'FFFBFBFBFBFBFBFFBFBFBFBFFBFBFFBFF'
"""
indices=""
for pos, i in enumerate(cards):
if i =="B":
indices+=str(pos)
first= int(indices[0])
last= int(indices[-1])
prefix= cards [:first]
middle= cards [first:last+1]
suffix= cards [last+1:]
middle2=swap(middle)
return (prefix+middle2+suffix)
def turns (cards):
"""
>>> turns('FBFFFBFFBF')
3
>>> turns('BFFBFBFFFBFBBBFBBBBFF')
6
>>> turns('FFBFBFBFBFBFBFBBFBFBFBFBBFBFBBFBF')
14
"""
turn=0
while cards != 'F'*len(cards):
cards=swap2(cards)
turn+=1
return (turn)
if __name__ == '__main__':
import doctest
doctest.testmod()
当我运行这个函数时,它工作得很好,但是如果我使用doctest来查看是否有错误,它会告诉我:
^{pr2}$我不知道错误从何而来。 有人能帮我吗?在
doctest的完整输出:
File "C:\Users\manuel\Documents\Gent MaStat\programming and algorithms\workspace_python\homeworks\Week 5\looking_up.py", line 25, in __main__.swap2
Failed example:
next('FBFFFBFFBF')
Exception raised:
Traceback (most recent call last):
File "C:\Users\manuel\Anaconda3\lib\doctest.py", line 1321, in __run
compileflags, 1), test.globs)
File "<doctest __main__.swap2[0]>", line 1, in <module>
next('FBFFFBFFBF')
TypeError: 'str' object is not an iterator
**********************************************************************
File "C:\Users\manuel\Documents\Gent MaStat\programming and algorithms\workspace_python\homeworks\Week 5\looking_up.py", line 27, in __main__.swap2
Failed example:
next('BFFBFBFFFBFBBBFBBBBFF')
Exception raised:
Traceback (most recent call last):
File "C:\Users\manuel\Anaconda3\lib\doctest.py", line 1321, in __run
compileflags, 1), test.globs)
File "<doctest __main__.swap2[1]>", line 1, in <module>
next('BFFBFBFFFBFBBBFBBBBFF')
TypeError: 'str' object is not an iterator
**********************************************************************
File "C:\Users\manuel\Documents\Gent MaStat\programming and algorithms\workspace_python\homeworks\Week 5\looking_up.py", line 29, in __main__.swap2
Failed example:
next('FFBFBFBFBFBFBFBBFBFBFBFBBFBFBBFBF')
Exception raised:
Traceback (most recent call last):
File "C:\Users\manuel\Anaconda3\lib\doctest.py", line 1321, in __run
compileflags, 1), test.globs)
File "<doctest __main__.swap2[2]>", line 1, in <module>
next('FFBFBFBFBFBFBFBBFBFBFBFBBFBFBBFBF')
TypeError: 'str' object is not an iterator
函数名为
swap2
,但在doctest中,您使用的是next
,它恰好是一个built-in function,它的作用完全不同。这就是你看到错误的原因。在在这种情况下,实际查看错误消息非常重要。它清楚地告诉你什么叫:
^{pr2}$所以,如果你不知道这是从哪里来的,那么检查一下错误信息。Doctest将告诉您它正在执行什么:
swap2[0]
,swap2[1]
,等等。告诉您Doctest正在执行的docstring函数名以及它是哪个测试用例(0
是第一个,1
是第二个等等)。它甚至给出了错误出现的行号(在doctest案例中),当然还有导致错误的行。因此,使用这些信息可以找到有问题的代码,并找出问题所在。在相关问题 更多 >
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