# [SciPy-user] CDF/PDF Stats with SciPy

Omer Khalid Omer.Khalid@cern...
Mon Jul 20 15:39:06 CDT 2009

```Hi Robert,

> >
> > Thanks for your reply. But I am getting a little confused here now. It
> seems
> > there are multiple ways to get the CDF for a distribution. You mean
> linspace
> > function returns a CDF for a normal distribution.
>
> No, not at all. linspace() returns uniformly increasing numbers
> between the given endpoints. Ivo showed you how to find the empirical
> CDF of the dataset. It is not related to any particular family of
> probability distributions.

Sorry for my ignorance, but what is Empirical CDF and how's that different
from a CDF lets say for Normal distribution or Piosson other than that it's
calculated differently?

>
>
> > As far as I understood from other sources is that scipy.stats.norm.cdf
> > (mean, std) will return the CDF for the normal distribution or for
> > non-normal distribution given one replace *norm* with the distributions
> > name.
>
> Yes.
>

OK, so that I understood correctly :-)

>
> > And what about scipy.stats.<dist>.fit function?
>
> It will find the maximum likelihood parameters for fitting the given
> distribution to your dataset. These parameters can be then used the
> the <dist> object to return the fitted CDF, PDF, etc. The .fit()
> method is not very flexible, though.

Sorry, what do you mean that .fit() is not very flexible?

And can you explain with some python code as then it would be easier for me
to understand.

Thanks,
Omer
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