I = 2; lst = [i ** = 2而i <1000] [英] i=2; lst=[i**=2 while i<1000]
问题描述
你好NG，
我想知道在这个
NG中是否有提议或以前的讨论，考虑在理解列表中使用''while'' br />
＃伪代码
i = 2
lst = [i ** = 2而i <1000]
当然这可以很容易地重写成
i = 2
lst = []
而i< 1000：
i ** = 2
lst.append（i）
通常我更喜欢一个衬里，比如
lines = [line.strip（）for line in file（" foo"）。readlines（）if line]
他们使目的明确
so如果在理解列表中允许''while''这将允许
写上简洁的代码
到上面的例子，我尝试了一个解决方法
i = 2
lst = [i ** = 2 for _ in iter（lambda：_< 1000，False）]
但是由于i ** = 2
而导致SyntaxError失效，并且必须重写为
Hello NG,
I am wondering if there were proposals or previous disscussions in this
NG considering using ''while'' in comprehension lists
# pseudo code
i=2
lst=[i**=2 while i<1000]
of course this could be easily rewritten into
i=2
lst=[]
while i<1000:
i**=2
lst.append(i)
usually I would prefer one liners like
lines=[line.strip() for line in file("foo").readlines() if line]
they make the purpose clear
so if ''while'' were allowed in comprehension list this would allow
to write concise code
to the example above, I tried a workaround
i=2
lst=[i**=2 for _ in iter(lambda:_<1000, False)]
but this failes with SyntaxError because of i**=2
and must be also rewritten into
i = 2
def f（）：
.... global i
....我** = 2
....返回我
.... lst = [f（）for _ in iter（lambda： i< 1000，False）]
lst
i=2
def f(): .... global i
.... i**=2
.... return i
.... lst=[f() for _ in iter(lambda:i<1000, False)]
lst
[4,16,256,65536]
我认为这与此相比损失了
i = 2
lst = [i ** = 2而i <1000]
问候，Daniel
[4, 16, 256, 65536]
I think this loses compared with
i=2
lst=[i**=2 while i<1000]
Regards, Daniel
推荐答案
DanielSchüle写道：
Daniel Schüle wrote:
Hello NG，
我想知道在这个
NG考虑在理解列表中使用''while'时是否有提议或先前的讨论
＃pseudo code
i = 2
lst = [i ** = 2而我<1000]
当然这可以很容易地改写成
我= 2
lst = []
而我< 1000：
我** = 2
lst.append（i）
Hello NG,
I am wondering if there were proposals or previous disscussions in this
NG considering using ''while'' in comprehension lists
# pseudo code
i=2
lst=[i**=2 while i<1000]
of course this could be easily rewritten into
i=2
lst=[]
while i<1000:
i**=2
lst.append(i)
因为你没有增加我，所以无休止地循环。
你可以在范围（1000）中使用i ** = 2代替
That would loop endlessly since you don''t increment i.
You can use i**=2 for i in range(1000) instead
DH写道：
D H wrote:
DanielSchüle写道：
Daniel Schüle wrote:
Hello NG，
我想知道是否有提案或以前在这个NG中的讨论考虑在理解列表中使用''while''
＃伪代码
i = 2
lst = [i ** = 2 while我< 1000]
当然这可以很容易地改写成
我= 1000：
我* * = 2
lst.append（i）
Hello NG,
I am wondering if there were proposals or previous disscussions in this
NG considering using ''while'' in comprehension lists
# pseudo code
i=2
lst=[i**=2 while i<1000]
of course this could be easily rewritten into
i=2
lst=[]
while i<1000:
i**=2
lst.append(i)
这会无休止地循环，因为你不会增加我。
你可以使用i ** = 2我在范围（1000）而不是
That would loop endlessly since you don''t increment i.
You can use i**=2 for i in range(1000) instead
我不认为可以在列表理解或生成器中使用赋值
表达式。限制非常像lambda。
I don''t think one can use assignment in list comprehension or generator
expression. The limitation is very much like lambda.
bo **** @ gmail.com 写道：
你可以在范围（1000）中使用i ** = 2代替
You can use i**=2 for i in range(1000) instead
我不认为可以在列表理解或生成器
表达式中使用赋值。限制非常像lambda。
I don''t think one can use assignment in list comprehension or generator
expression. The limitation is very much like lambda.
i ** 2
i**2
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