It's great to have you chime in, Steven. I do wish you would stop
pulling your punches, however. ;)
On Fri, Oct 22, 2010 at 17:23, Steven D'Aprano <st...@pearwood.info> wrote:
> On Sat, 23 Oct 2010 12:42:50 am Richard D. Moores wrote:
>
>> So I wrote a function:
>>
>> def float2n_decimals(floatt, n):
>> """
>> Given a float (floatt), return floatt to n decimal places.
>>
>> E.g., with n = 2, 81.34567 -> 81.35
>> """
>> return ("%%.%sf" % n) % floatt
>>
>> which works fine,
>
>
> float2n_decimals(x, 3)
>
> is better written in place as:
>
> "%.*f" % (3, x)
>
> There's no need for a function for something so simple.
Yes, but I needed one for ("%%.%sf" % n) % floatt .
>> but a question remains: n is an integer. Why the
>> 's' in '%sf'?
>
> Your function might be more clear if you split the formatting into two
> lines:
>
> template = "%%.%sf" % n
> return template % floatt
>
> The first line builds a template string from n. Now it becomes clear
> what %s is for: it's to insert the n as a string into the template. %d
> would express the intention of the function better.
>
OK, I'll do that.
>
> By the way, the function docstring is seriously misleading. It describes
> a completely different function:
>
>> Given a float (floatt), return floatt to n decimal places.
>>
>> E.g., with n = 2, 81.34567 -> 81.35
>
> It does nothing of the sort! What you are describing is the built-in
> function round:
>
>>>> print round(81.34567, 2)
> 81.35
>
> What your function does is return a string, not a float.
OK, point well-taken.
> Besides, given
> a float, where does n come from? A global variable?
Yes. See line 5 of <http://tutoree7.pastebin.com/M2wnPzLr>. This
version incorporates all your suggestions.
> There is a convention for giving examples that you should follow.
> Putting the three of these together, your docstring should say
> something like:
>
> Given a float floatt and an integer n, returns floatt formatted
> as a string to n decimal places.
>
> >>> float2n_decimals(2, 81.34567)
> '81.35'
I've never seen that convention, but I'll try to follow it.
>
> (BTW, I really hate the name "floatt". It makes me think you're
> stuttering.)
I'll use "x" instead. Anything you'd like to say about the rest of the script?
Thanks, Steven.
Dick
_______________________________________________
Tutor maillist - Tutor@python.org
To unsubscribe or change subscription options:
http://mail.python.org/mailman/listinfo/tutor
