[Numpy-discussion] Combining Sigmoid Curves

Christopher Barker Chris.Barker@noaa....
Fri May 2 17:59:55 CDT 2008


Anne Archibald wrote:
> 2008/5/2 Rich Shepard <rshepard@appl-ecosys.com>:
> No, no. You *want* scaled_x to range from -1 to 1. 

Why not just scale to -pi to pi right there?

(The 0.998 is because you didn't include the endpoint, 100.)

Which is why you want linspace, rather than arange. Really, trust me on 
this!

If the cosine curve isn't right for you, a little create use of np.where 
would let you do what you want in maybe another line or two of code. 
Something like:

y = np.where( x < 0 , Leftfun(x), Rightfun(x) )

or just compute one side and then flip it to make the other side:

y = np.zeros_like(x)
y[center:] = fun(x[center:])
y[:center] = y[center+1:][::-1] # don't want the center point twice

if it's symetric anyway.

-Chris


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Christopher Barker, Ph.D.
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