Re: [Matplotlib-users] ValueError: x and y must have same first dimension

[surfcast23 <sur...@gm...>]

Thanks for catching that sigma was still a vector! I am no longer getting the
errors, but the best fit line is not showing up.Is there something else I am
missing ?
BTW thanks for the heads up on the np.mean and np.standard functions. 

Khary 

Daπid wrote:
> 
> On Fri, Jul 27, 2012 at 9:57 PM, surfcast23 <sur...@gm...> wrote:
>> y = mlab.normpdf( nbins, avg, sigma)
>> l = plt.plot(nbins, y, 'r--', linewidth=1)
>> plt.show()
> 
> You should not change bins there, as you are evaluating the gaussian
> function at different values.
> 
> Also, sigma is a vector, but it should be an scalar:
> 
> sigma = np.sqrt((1./len(C))*(diff**2))
> 
> should be
> 
> sigma = np.sum(np.sqrt((1./len(C))*(diff**2)))    # The sum of the
> previous
> 
> But, much better, you can change the three lines of code by:
> 
> avg=np.mean(C)
> sigma=np.std(C)
> 
> They are way faster and more numerically accurate and stable.
> 
> 
> As a rule of thumb, if you want to do something simple, think that
> there should be an easy way of doing it. And if it is something people
> do every day (like taking the mean or the std of a vector, or loading
> from a txt file), there should be a very easy way of doing it. :-) And
> it would probably be faster and more flexible than any naive
> implementation.
> 
> 
> Good luck with your galaxies!
> 
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