Re: [Tutor] Change dictionary value depending on a conditional statement.
I don't think I saw anyone point this out yet, but, using "list" as a
variable name is a bad idea, because it hides the list method.
>>> x = list("abcdefg")
>>> x
['a', 'b', 'c', 'd', 'e', 'f', 'g']
This works. You now have a variable named "x" that is a list.
>>> list = list("hijklmnop")
>>> list
['h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p']
This works, sort of. You now have a variable named "list" that is a list.
But since you reused the name "list," it can no longer point to the list
function.
>>> y = list("qrstuv")
Traceback (most recent call last):
File "", line 1, in
TypeError: 'list' object is not callable
And so this fails.
On Tue, 12 Feb 2008, Norman Khine wrote:
> Thank you all, very nice.
>
> Steve Willoughby wrote:
> > Kent Johnson wrote:
> >> Try
> >>list.append({'id': 'name', 'link': ('YY','XX')[total > 0]})
> >
> > I'd caution against that, though. It's clever and cute, sure, but the
> > meaning of it is obfuscated enough to be unpythonic because [total > 0]
> > as a subscript doesn't mean anything unless you know you're taking
> > advantage of an implementation detail that booleans are 0 for false and
> > 1 for true. No matter how reliable that fact may be, I don't think that
> > value should be stuck into a numeric context like that.
> >
> >> Or, in Python 2.5,
> >>list.append({'id': 'name', 'link': ('XX' if total > 0 else 'YY')})
> >
> > This is much more clear, and would IMHO be fine.
> >
> >
> >
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> >
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Re: [Tutor] Change dictionary value depending on a conditional statement.
Thank you all, very nice.
Steve Willoughby wrote:
> Kent Johnson wrote:
>> Try
>>list.append({'id': 'name', 'link': ('YY','XX')[total > 0]})
>
> I'd caution against that, though. It's clever and cute, sure, but the
> meaning of it is obfuscated enough to be unpythonic because [total > 0]
> as a subscript doesn't mean anything unless you know you're taking
> advantage of an implementation detail that booleans are 0 for false and
> 1 for true. No matter how reliable that fact may be, I don't think that
> value should be stuck into a numeric context like that.
>
>> Or, in Python 2.5,
>>list.append({'id': 'name', 'link': ('XX' if total > 0 else 'YY')})
>
> This is much more clear, and would IMHO be fine.
>
>
>
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>
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Re: [Tutor] Change dictionary value depending on a conditional statement.
Kent Johnson wrote:
> Try
>list.append({'id': 'name', 'link': ('YY','XX')[total > 0]})
I'd caution against that, though. It's clever and cute, sure, but the
meaning of it is obfuscated enough to be unpythonic because [total > 0]
as a subscript doesn't mean anything unless you know you're taking
advantage of an implementation detail that booleans are 0 for false and
1 for true. No matter how reliable that fact may be, I don't think that
value should be stuck into a numeric context like that.
> Or, in Python 2.5,
>list.append({'id': 'name', 'link': ('XX' if total > 0 else 'YY')})
This is much more clear, and would IMHO be fine.
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Re: [Tutor] Change dictionary value depending on a conditional statement.
bob gailer wrote:
> The terse version:
>
> list.append({'id': 'name', 'link': ('XX','YY')[total > 0]})
I think you have it backwards:
In [1]: total=0
In [2]: ('XX','YY')[total > 0]
Out[2]: 'XX'
In [3]: total=1
In [4]: ('XX','YY')[total > 0]
Out[4]: 'YY'
Try
list.append({'id': 'name', 'link': ('YY','XX')[total > 0]})
Or, in Python 2.5,
list.append({'id': 'name', 'link': ('XX' if total > 0 else 'YY')})
Kent
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Re: [Tutor] Change dictionary value depending on a conditional statement.
Norman Khine wrote:
> Hello,
> Is there a better way to do this:
>
> >>> list = []
> >>> total = 0
> >>> if total > 0:
> ... x = {'id': 'name', 'link': 'XX'}
> ... list.append(x)
> ... else:
> ... y = {'id': 'name', 'link': 'YY'}
> ... list.append(y)
> ...
>
> I would like to change the key 'link' value depending on the value of
> 'total' so for example if total == 2, then append x else y to the list.
>
The terse version:
list.append({'id': 'name', 'link': ('XX','YY')[total > 0]})
--
Bob Gailer
919-636-4239 Chapel Hill, NC
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[Tutor] Change dictionary value depending on a conditional statement.
Hello,
Is there a better way to do this:
>>> list = []
>>> total = 0
>>> if total > 0:
... x = {'id': 'name', 'link': 'XX'}
... list.append(x)
... else:
... y = {'id': 'name', 'link': 'YY'}
... list.append(y)
...
I would like to change the key 'link' value depending on the value of
'total' so for example if total == 2, then append x else y to the list.
Thanks
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