Re: [Matplotlib-users] Getting data from a figure

[Richard B. <rg...@gm...>]

On 30/03/07, bre...@un...
<bre...@un...> wrote:
>
> Not sure what region[:] is supposed to achieve.  You are creating a copy
> with the same name, so you are over-riding the original variable.
>

That doesn't seem to be the case - it returns the right thing on the
first call - i.e. region got changed, but on subsequent calls the
figure is displayed and the function returns array([0,0,0,0]). I
thought taking the slice just gave access to the internals of region
...

How does one assign a new value to a variable in a containing scope?

Richard


>
> Hi there
>
> I have a function where I want to display an image, get the user to
> zoom in on a region of interest, and then return the axes limits.
>
> But the problem is, I can only use it once, the second time it gets
> called in a script the figure doesn't appear. I know this is to do
> with show() not being supposed to be used multiple times, but I don't
> know what I should be doing instead ... any tips? (I'm still new to
> python btw)
>
> Also, if there's a better (more pythonic way) to do what I'm doing, I
> would appreciate your input. I'm not sure if what I'm doing with the
> region variable is dodgy or not.
>
> Currently, I'm doing this:
>
> from pylab import *
>
> def getroi(im):
>    imshow(im)
>    title('Zoom in to region of interest, then press a key')
>    region = array([0, 0, 0, 0]) # Placeholder values
>
>    def keypressed(event):
>        region[:] = [round(i) for i in gca().axis()]
>        close(gcf())
>
>    # Connect keypressed to event handler
>    connect('key_press_event', keypressed)
>
>    show()
>    return region
>
>
>
> thanks,
>
> Richard