Floating numbers and str

[Tuvas]

I would like to limit a floating variable to 4 signifigant digits, when
running thorugh a str command. Ei,


x=.13241414515
y=str(x)+" something here"

But somehow limiting that to 4 sign. digits. I know that if you use the
print statement, you can do something like %.4d, but how can I do this
with converting the number to a string? Thanks!

[Jeffrey Schwab]

Re: Floating numbers and str

Tuvas wrote:[color=blue]
> I would like to limit a floating variable to 4 signifigant digits, when
> running thorugh a str command. Ei,
>
>
> x=.13241414515
> y=str(x)+" something here"
>
> But somehow limiting that to 4 sign. digits. I know that if you use the
> print statement, you can do something like %.4d, but how can I do this
> with converting the number to a string? Thanks![/color]

%d for a floating-point type? Is that right?

Anyway, ITYW:

"%.4g" % x

E.g:
[color=blue][color=green][color=darkred]
>>> x=.13241414515
>>> y="%.4g something here" % x
>>> print y[/color][/color][/color]
0.1324 something here[color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

[Jeremy Moles]

Re: Floating numbers and str

I think you answered your own question. :)

x = 0.12345678
y = "%.4f something here" % x

On Wed, 2005-11-09 at 11:52 -0800, Tuvas wrote:[color=blue]
> I would like to limit a floating variable to 4 signifigant digits, when
> running thorugh a str command. Ei,
>
>
> x=.13241414515
> y=str(x)+" something here"
>
> But somehow limiting that to 4 sign. digits. I know that if you use the
> print statement, you can do something like %.4d, but how can I do this
> with converting the number to a string? Thanks!
>[/color]

[Tuvas]

Re: Floating numbers and str

Yep, I was thinking in C, not python. Thanks for the help!

[Grant Edwards]

Re: Floating numbers and str

On 2005-11-09, Tuvas <tuvas21@gmail. com> wrote:
[color=blue]
> I would like to limit a floating variable to 4 signifigant digits, when
> running thorugh a str command.[/color]

Sorry, that's not possible.
[color=blue]
> x=.13241414515
> y=str(x)+" something here"
>
> But somehow limiting that to 4 sign. digits. I know that if
> you use the print statement, you can do something like %.4d,
> but how can I do this with converting the number to a string?[/color]

I don't understand what you mean about the print statement.

If using str() isn't really a requirement, you can use the
string formatting operator "%" like this:
[color=blue][color=green][color=darkred]
>>> x=.13241414515
>>> y = "%0.4g" % x
>>> y[/color][/color][/color]
'0.1324'

--
Grant Edwards grante Yow! A GRAM?? A BRAM... A
at GROOM... A BROOM... Oh,
visi.com Yeh!! Wash the ROOM!!

[Tuvas]

Re: Floating numbers and str

Wait, one more question. If the number is something like:

1.32042

It is like
"1.32 stuff"

I would like it's size to remain constant. Any way around this?

[Fredrik Lundh]

Re: Floating numbers and str

"Tuvas" <tuvas21@gmail. com> wrote:
[color=blue]
>I would like to limit a floating variable to 4 signifigant digits, when
> running thorugh a str command. Ei,
>
> x=.13241414515
> y=str(x)+" something here"
>
> But somehow limiting that to 4 sign. digits. I know that if you use the
> print statement, you can do something like %.4d, but how can I do this
> with converting the number to a string? Thanks![/color]

you mean "%.4g" ? the % operator is a string operator, and can be used
outside print:

text = "%.4g" % value

for more details, here's the first google hit for "python string formatting":

http://docs.python.org/lib/typesseq-strings.html

but that doesn't make too much sense if you don't know how things work
in C, which is explained here:

http://www.cplusplus.com/ref/cstdio/printf.html

here are some examples:
[color=blue][color=green][color=darkred]
>>> x=.13241414515
>>> x[/color][/color][/color]
0.13241414515[color=blue][color=green][color=darkred]
>>> "%.4f" % x[/color][/color][/color]
'0.1324'[color=blue][color=green][color=darkred]
>>> "%.4g" % x[/color][/color][/color]
'0.1324'
[color=blue][color=green][color=darkred]
>>> x=5.13241414515
>>> "%.4f" % x[/color][/color][/color]
'5.1324'[color=blue][color=green][color=darkred]
>>> "%.4g" % x[/color][/color][/color]
'5.132'

</F>

[Grant Edwards]

Re: Floating numbers and str

On 2005-11-09, Tuvas <tuvas21@gmail. com> wrote:[color=blue]
> Wait, one more question. If the number is something like:
>
> 1.32042
>
> It is like
> "1.32 stuff"
>
> I would like it's size to remain constant. Any way around this?[/color]

http://www.python.org/doc/current/lib/typesseq-strings.html#l2h-211

--
Grant Edwards grante Yow! WHO sees a BEACH
at BUNNY sobbing on a SHAG
visi.com RUG?!

[Dan Bishop]

Re: Floating numbers and str

Grant Edwards wrote:[color=blue]
> On 2005-11-09, Tuvas <tuvas21@gmail. com> wrote:
>[color=green]
> > I would like to limit a floating variable to 4 signifigant digits, when
> > running thorugh a str command.[/color]
>
> Sorry, that's not possible.[/color]

Technically, it is.
[color=blue][color=green][color=darkred]
>>> class Float4(float):[/color][/color][/color]
.... def __str__(self):
.... return '%.4g' % self
....[color=blue][color=green][color=darkred]
>>> x = Float4(1.234567 89)
>>> str(x)[/color][/color][/color]
'1.235'

But, of course, I'd recommend just using '%.4g'%x directly.

[Grant Edwards]

Re: Floating numbers and str

On 2005-11-10, Dan Bishop <danb_83@yahoo. com> wrote:[color=blue]
> Grant Edwards wrote:[color=green]
>> On 2005-11-09, Tuvas <tuvas21@gmail. com> wrote:
>>[color=darkred]
>> > I would like to limit a floating variable to 4 signifigant digits, when
>> > running thorugh a str command.[/color]
>>
>> Sorry, that's not possible.[/color]
>
> Technically, it is.[/color]

Ah well, I assumed that by "floating variable" he meant the
built-in "float" type.

--
Grant Edwards grante Yow! I always wanted a
at NOSE JOB!!
visi.com

[Jeffrey Schwab]

Re: Floating numbers and str

Tuvas wrote:[color=blue]
> Wait, one more question. If the number is something like:
>
> 1.32042
>
> It is like
> "1.32 stuff"
>
> I would like it's size to remain constant. Any way around this?[/color]

s/%g/%f
[color=blue][color=green][color=darkred]
>>> print "%.4f stuff" % 1.3241414515[/color][/color][/color]
1.3241 stuff[color=blue][color=green][color=darkred]
>>> print "%.4f stuff" % 1.32042[/color][/color][/color]
1.3204 stuff[color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

[Christian Stapfer]

Re: Floating numbers and str

"Tuvas" <tuvas21@gmail. com> wrote in message
news:1131565949 .678342.39890@g 44g2000cwa.goog legroups.com...[color=blue]
>I would like to limit a floating variable to 4 signifigant digits, when
> running thorugh a str command. Ei,
>
>
> x=.13241414515
> y=str(x)+" something here"
>
> But somehow limiting that to 4 sign. digits. I know that if you use the
> print statement, you can do something like %.4d, but how can I do this
> with converting the number to a string? Thanks![/color]

from scipy import round

print round(0.1324141 4515,4)

Regards,
Christian