Re: [Matplotlib-users] Fwd: Re: Colobar and change axis x and y labels

[Jerzy K. <jer...@un...>]

"Pythphys", would it be too demanding to ask you to sign your messages 
with a human name?...
Danke.

You ask:

> - changing to an image grey scale only needs ... what?
plt.set_cmap(plt.cm.gray)

in the context of your current figure. Or, use cmap=... in your imshow.
Please, look up "colormap" in the documentation.

> - I need to do a 'plane fit' of the image. Does matplotlib
>     have some routine for this? Or shall I use other math libs?

I am not a guru of matplotlib, but this is a visualisation package, not 
a data processing one. Scipy (numpy) have some interpolation procedures, 
polyfit, etc. but I don't remember without digging the docs (which you 
might do as well) whether multidimensional fitting is there.

Anyway, why not use your head? This is a standard student exercise.

You need to fit:   zf = ax + by + c, having z =f(x,y) in your image, am 
I right? If not, forget the rest.

Use the linear regression, find the zero of the gradient wrt (a,b,c) of

SUM[(ax +by +c - z)^2]

and that's all.

The most tragic part of the exercise is the necessity of solving a 
linear equation set in 3 variables...

Jerzy Karczmarczuk
Caen, France