[Matplotlib-users] dataLim and getting the data from `scatter` (bonus: an attempt at a Frame class)

[Tony S Yu <to...@MI...>]

Hi. A couple of questions about `scatter`:

Q1
====

The bounding box `axes.dataLim` increases in size when calling  
scatter(x, y) compared to plot(x, y) (for the same x, y data, of  
course). I think this change is due to the size of the markers being  
added to the data limits (not sure if this is true). Is there an easy  
way to get the same data limits I would have for a call to `plot`?

Q2
====

Is there a way to get the data from the axes of a scatter plot?

Initially I thought I could get it with:

 >>> for collection in ax.collections:
 >>>     for path in collection._paths:
 >>>         print path.vertices

But this seems to be the path that draws the scatter markers. Any ideas?

Frame Class
==========

Finally, if anyone is interested, I'm playing around with a Frame  
class for `axes.frame`. This class adds customizable axes frames  
similar to the topic of this thread:
http://sourceforge.net/mailarchive/message.php?msg_id=87d57vjgye.fsf%40peds-pc311.bsd.uchicago.edu
In this older thread, the SAGE axes frames were criticized for not  
being flexible enough. I've tried to make this class as general as  
possible (within my ability:).  As an example of the flexibility of  
this Frame class, I've added some Tufte-style frames similar to:
http://hupp.org/adam/weblog/2007/09/03/etframes-applying-the-ideas-of-edward-tufte-to-matplotlib/

To the developers on this thread: If there's anything I could do to  
make the attached Frame class more flexible (and more suitable for  
possible inclusion into MPL), I'd be happy to get some feedback.

Current Limitations:
================
* the frame can only be placed on the borders of the axes (mainly  
because I don't know how to move the tickers anywhere else).
* RangeFrame only works with linear data (I'm not sure how to use the  
`axes.transScale` to properly transform the data)
* RangeFrame and DashDotFrame don't work properly with `scatter`  
(because of the questions in this post).

The frame class itself isn't too long, but I got a little carried away  
adding in extra crap.

Sorry for the long, rambling email.;)
-Tony