matplotlib-users Mailing List for matplotlib

Jouni K Seppanen wrote:
>It looks like the sys.platform check is trying to guard against this
>condition, but plain Mac Python without py2app does not have
>sys.frozen. I suppose it would be better to check whether sys.frozen
>exists and then its truth value. Would the following change work for
>everyone?
> 
>
Hi Jouni,
I applied your patch in SVN revision 2166. Thanks for the pointer.
Cheers!
Andrew

"Charlie Moad" <cw...@gm...> writes:
> On 2/19/06, Josh Marshall <jos...@gm...> wrote:
>> Change the line to either:
>> if (sys.platform=='win32' or sys.platform=='darwin') and sys.frozen:
>
> Done.
This is causing problems on OS X, since (on at least Python 2.4.1 on
Tiger from http://undefined.org/python/) sys.platform is 'darwin' but
sys.frozen does not exist:
>>> sys.platform
'darwin'
>>> sys.frozen
Traceback (most recent call last):
 File "<stdin>", line 1, in ?
AttributeError: 'module' object has no attribute 'frozen'
It looks like the sys.platform check is trying to guard against this
condition, but plain Mac Python without py2app does not have
sys.frozen. I suppose it would be better to check whether sys.frozen
exists and then its truth value. Would the following change work for
everyone?
Index: lib/matplotlib/__init__.py
===================================================================
--- lib/matplotlib/__init__.py (revision 2151)
+++ lib/matplotlib/__init__.py (working copy)
@@ -349,7 +349,7 @@
 if os.path.isdir(path): return path
 
 # py2exe zips pure python, so still need special check
- if (sys.platform=='win32' or sys.platform=='darwin') and sys.frozen:
+ if getattr(sys, 'frozen', None):
 path = os.path.join(os.path.split(sys.path[0])[0], 'matplotlibdata')
 if os.path.isdir(path): return path
 else:
See also: http://pythonmac.org/wiki/FAQ#head-fda52eabc4c64a21d7044d62a49319a7c85faca9
The reason I ran into this was that I installed the svn version with
"setupegg.py develop"1, and there is no mpl-data directory in
lib/matplotlib. I made a symlink to an existing mpl-data directory,
but I wonder if there is some more elegant way for matplotlib to
support setuptools' develop mode?
1 http://mail.python.org/pipermail/distutils-sig/2005-July/004692.html
-- 
Jouni

John,
It might be nice if we could add a "what if" type function to all the 
backends for text sizing. That way we could write much better auto-layout 
algorithms for the axis and legend code. A very simple improvement to the 
auto-date labeller would then work like this:
- Find min, max values of the time axis
- Convert to the label format using the date formatter
- Ask the backend what the size of the min/max labels would be
- Take the max of that as a reasonable guess for the date label size
- Divide up the total interval (in pixels) by the label size + pad
- Pick nice ticks based on the total time interval and number of ticks you 
can fit
This would be really handy for us in that we do a lot of date plotting with 
widely varying time ranges and it would be nice to have an "auto-ticker" 
that insures the labels don't overlap for a plot of a given size and range.
On a scale of 1-10, how difficult do you think this type of thing would be 
to do?
Ted
At 07:52 PM 3/17/2006, John Hunter wrote:
> >>>>> "Michael" == Michael P Mossey <mo...@jp...> writes:
>
> Michael> Is there a way to find out in terms of pixels, points, or
> Michael> fraction of figure, how large a text string is? In other
> Michael> words if I generate "Some label" as the x-axis label, can
> Michael> I find out how tall and wide it is?
>
>It can be done -- it's not terribly elegant. The basic problem is
>that text size depends on the backend and configuration settings.
>Since we have arbitrary fonts, multiline text with arbitrary rotation,
>possible using TeX to render, with multiple output targets that might
>handle text differently, you can see how this seemingly simple
>question is actually tough.
>
>All text instances have a method called "get_window_extent" which
>returns a matplotlib.transforms.BBox that bounds the text instance.
>This bbox is in pixel coords.
>
> bbox = sometext.get_window_extent()
> l,b,w,h = bbox.get_bounds() # left, bottom, width, height
>
>
>Here's the rub: we can't realistically know the text size until we
>have a renderer, because the same text may be different in different
>renderers. matplotlib sets the figure renderer at draw time, and so
>by default we don't know the text size until draw size. This is
>sometimes cumbersome.
>
>One solution is to do something like
>
> plot(something)
> sometext = text(x,y,s)
> draw() # force a draw to set the renderer
> l,b,w,h = sometext.get_window_extent().get_bounds()
> ..adjust the postion of some objects based on this info
> ...draw again
>
>not terribly elegant because we must redraw. If you did not first
>force the draw command before calling get_window_extent, you would get
>an exception about needing to first set the renderer.
>
>Another approach if you want to avoid the duplicate drawing is to
>create a proxy renderer and pass that off to the text instance.
>
> l,b,w,h = fig.bbox.get_bounds()
> renderer = RendererAgg(w, h, fig.dpi)
> l,b,w,h = sometext.get_window_extent(renderer).get_bounds()
>
>This is not ideal either because you have a duplicate renderer.
>
>If you are using a *Agg backend and have a figure instance, you can do
>the following, which requires no duplicate drawing and no duplicate
>renderer (the get_renderer method below caches the return value so
>repeated calls do not create duplicate renderers)
>
>Here is a complete example
>
> from matplotlib.patches import Rectangle
> from matplotlib.transforms import identity_transform
> from pylab import figure, show
>
> fig = figure()
> ax = fig.add_subplot(111)
> ax.plot([1,2,3,4], [1,2,3,4])
> t = ax.text(2,2,'Look Ma!\nNo hands', fontsize=40, rotation=-45)
> renderer = fig.canvas.get_renderer()
> bbox = t.get_window_extent(renderer)
> l,b,w,h = bbox.get_bounds()
>
> # no transformation necessary, already in pixel coords
> r = Rectangle((l,b),w,h, transform=identity_transform())
> ax.add_patch(r)
> show()
>
>If we made the get_renderer method standard across backends, we could
>probably hide the get_renderer call from the user and make this a
>little more friendly, but the above should suffice. Note if you have
>some data in pixel coords, you can transform it into another
>coordinate system (eg data coords) using the inverse transform
>methods. The l,b,w,h bounding box of the text bbox in "data"
>coordinates (ie, the coords of the [1,2,3,4] plot) can be obtained
>with
>
> from matplotlib.transforms import inverse_transform_bbox
> databbox = inverse_transform_bbox(ax.transData, bbox)
> print databbox.get_bounds()
>
>In general, different coordinate systems in matplotlib communicate
>with one another by transforming a data point to pixel space and then
>inverse transforming that point into a different own space. There are
>two inverse methods to help with these tasks. The first is a
>transform method to handle single points:
>
> # apply the inverse transformation to tuple xy
> xi, yi = trans.inverse_xy_tup(xy)
>
>and the second is a stand-alone function defined in
>matplotlib.transforms to handle bboxes
>
> # apply the inverse transformation of a bbox
> bboxi = inverse_transform_bbox(trans, bbox)
>
>
>You might be thinking: why aren't we simply using an affine
>transformation matrix with a standard matrix inverse? All I can offer
>in response is that this architecture supports nonlinear
>transformations, ie, an affine plus a nonlinear transformation, for
>polar, log, etc.... There is probably a better way, but this is what
>we've got.
>
>JDH
>
>
>
>
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