[SciPy-user] scipy.stats.lognorm

Matthieu Brucher matthieu.brucher@gmail....
Fri Sep 28 02:16:24 CDT 2007


Hi,

Do not worry about loc and scale. The first thing to know is that you modify
the shape of your distribution with s. Then, with loc and shape, you can
move the center and change the scale. Don't think that scale is another way
of defining the shape, it's only a way to change the scale of the
distribution.

Matthieu

2007/9/28, Manu Hack <manuhack@gmail.com>:
>
> Hi all,
>
> I have a quick question on scipy.stats.lognorm.  From the manual it said:
>
>     Lognormal distribution
>
>     lognorm.pdf(x,s) = 1/(s*x*sqrt(2*pi)) * exp(-1/2*(log(x)/s)**2)
>     for x > 0, s > 0.
>
> At the same time there are loc and scale to control the shape of the
> distribution.  So it's like there are 3 parameters to control the
> shape of the distribution (but 2 should be enough to specify one).
> In fact, if we look at R, the function dlnorm, plnorm, etc.  are
> simple and just did the job.  And after searching and trying different
> parameters and compare with R's function, I still couldn't figure out
> how to use scipy.stats.lognorm.  So am I missing anything there?
>
> Manu
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