[wxPython-users] FloatCanvas x/y scaling question

[Christopher Barker]

Grant,

if we get into much more detail, we might want to move the thread over =

to the FloatCanvas mailing list. I've cc'd that list, as I like to have =

this sort of thing archived.

Grant Edwards wrote:
> In a FloatCanvas, I can't seem to find a way to unlock the x
> scaling and the y scaling.  Is that not possible?

oddly enough, I don't think anyone has had the need for this yet...

> Does one use a projection function for that?  =


That should be able to do it.

> I'm plotting a triangulation where the x values range from
> 50e-6 to 2000e-6, and the y values range from 0 to 50000, so
> having the x and y scaled the same doesn't produce very useful
> results.  ;)

I'm trying to figure out what what delauney triangulation means when x =

and y have different units...nevertheless,

> If so, what is the API for a projection function?
 > Google wasn't able to find any examples or docs for a projection
> function.

Do you have the new distro? (rather than the one built in to wx.lib?) It =

has at least one example: YDownDemo.py

The api is:

a projection function takes the (x,y) coords of the center of the =

viewport, and returns a (Xscale, Yscale) vector that, when multiplied by =

a NX2 numpy array of (x,y) points, give the desired values.

clear as mud?

In your case, I think you want something like:

def YScaleFun(center):
     """
     function that returns a scaling vector to scale y data to same =

range as x data

     """
     #center gets ignored in this case
     return N.array((5e7, 1), N.float)

example enclosed.

-Chris




-- =

Christopher Barker, Ph.D.
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