grab more points from a database when panning?

I've got the NavigationToolbar2 going nicely on my app
(OO, embedded in wx, mpl 0.98.5), and was wondering
how difficult it might be to change how the pan works,
in the following way...

Right now, when I show a plot, I am grabbing a subset
of data from the database. Panning within that plot
allows exploration of *just that data*. E.g., if I have
values between x = 100 and x = 200, I can pan past
either of these values, but there are no more data points
beyond that, because I didn't fetch those points when I
created the plot.

What would be nice is if, on panning, I could fetch
new points, namely those that are found in that part of
the x axis. This would be just like Google Maps' ability
to allow one to pan the map over and see new land area,
because it fetches those land patches of the map.

I could of course just fetch all the data I have first
and set the x limits to show the requested subset
of data initially, but I thought maybe it would
be more efficient to only get what is requested and
then grab more data on pans. I thought I'd ask if
anyone had done something like this already.

Thanks,
Che

In SVN trunk, there is an example in examples/event_handling/viewlims.py that redraws a fractal when you zoom in. You could probably adopt a similar approach to grab new data points, though the details would depend on the type of plot.

Ryan

···

On Mon, Mar 30, 2009 at 1:34 PM, C M <cmpython@…287…> wrote:

I’ve got the NavigationToolbar2 going nicely on my app

(OO, embedded in wx, mpl 0.98.5), and was wondering

how difficult it might be to change how the pan works,

in the following way…

Right now, when I show a plot, I am grabbing a subset

of data from the database. Panning within that plot

allows exploration of just that data. E.g., if I have

values between x = 100 and x = 200, I can pan past

either of these values, but there are no more data points

beyond that, because I didn’t fetch those points when I

created the plot.

What would be nice is if, on panning, I could fetch

new points, namely those that are found in that part of

the x axis. This would be just like Google Maps’ ability

to allow one to pan the map over and see new land area,

because it fetches those land patches of the map.

I could of course just fetch all the data I have first

and set the x limits to show the requested subset

of data initially, but I thought maybe it would

be more efficient to only get what is requested and

then grab more data on pans. I thought I’d ask if

anyone had done something like this already.


Ryan May
Graduate Research Assistant
School of Meteorology
University of Oklahoma
Sent from Enterprise, Alabama, United States