matplotlib-devel Mailing List for matplotlib

Hi,
I think I've found a bug in matplotlib 0.53. The bug can be triggered
with the following commands

from matplotlib.matlab import *
plot(arange(40), array([1]*40))
show()

Basically, bad things happen if you try to plot a flat line. By
themselves, flat lines aren't very interesting, but they do occasionally
show up in the automated graphing batches I do. The first problem is an
easily patched bug in ticker.py where matplotlib tries to take the
logarithm of the interval span of the input data. For a constant data
series, that interval span is zero, and log(0) is naturally unhappy. 

Unfortunately, after fixing that problem, another problem arises. In
transformer.py, a divide by zero is triggered when trying to determine
display scale for much the same reason.

I've patched these bugs as best I can, but my fix isn't worth much since
the results look awful (no tick marks, data is uncentered). Its probably
best to let someone who knows what they're doing fix this for real.

Thanks a lot,
Mike Salib

>>>>> "Todd" == Todd Miller <jm...@st...> writes:

    Todd> No, not yet.  I was thinking about adding a minimal Matrix
    Todd> class to the numarray half of matplotlib.numerix for now.
    Todd> Then I'll add a more full-featured Matrix class to
    Todd> numarray-1.0.  Does that sound OK?

Sounds great - all I need is Matrix multiplication -- cf,
text.Text.get_rotation and text.Text._get_text_shift_and_size

JDH

On Tue, 2004-05-04 at 14:32, John Hunter wrote:
> I factored matplotlib.text.Text instances and layouts out of the
> backends.  Now matplotlib.text.Text does all the layout and passes the
> backends a *string* plus font properties etc.  This simplifies the
> text handling on the backends considerably, which only need to know
> how to compute the width and height of an unrotated string.  The
> frontend will then do the proper alignment for rotated text.
> 
> The benefits of these changes are
> 
>   * simpler backends
> 
>   * arbitrary rotated text layout works in agg, gd, and PS
> 
>   * this lays the ground work for newline spearated text across
>     backends since the layout will be on the front and the frontend
>     can pass the backends newline split strings to render.
>  
>   * the backend draw_text method is now is consistent with other
>     backend methods, eg draw_lines, draw_rectangles.  That is, the
>     backends no nothing about matplotlib.Artists
> 
> KNOWN BUGS
> 
>   * vertical text problem in PS to be fixed
> 
> This was a pretty comprehensive change so I recommend syncing your CVS
> tree.
> 
> Todd, I needed Numeric.Matrix to do the linear algebra for the
> rotations in the text module text.  Is there a numarray equivalent
> that we can expose in numerix?

No, not yet.  I was thinking about adding a minimal Matrix class to the
numarray half of matplotlib.numerix for now.  Then I'll add a more
full-featured Matrix class to numarray-1.0.  Does that sound OK?

Todd

> 
> Paul, I committed these changes after synching with your new font
> caching and there doesn't appear to be any problem; miraculously CVS
> seems to be working pretty well.  I did some additional caching of AFM
> instances in backend_ps.  You might want to rerun your ps profile
> script and see if the numbers improve further still.
> 
> JDH
> 
> 
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-- 
Todd Miller <jm...@st...>

I factored matplotlib.text.Text instances and layouts out of the
backends.  Now matplotlib.text.Text does all the layout and passes the
backends a *string* plus font properties etc.  This simplifies the
text handling on the backends considerably, which only need to know
how to compute the width and height of an unrotated string.  The
frontend will then do the proper alignment for rotated text.

The benefits of these changes are

  * simpler backends

  * arbitrary rotated text layout works in agg, gd, and PS

  * this lays the ground work for newline spearated text across
    backends since the layout will be on the front and the frontend
    can pass the backends newline split strings to render.
 
  * the backend draw_text method is now is consistent with other
    backend methods, eg draw_lines, draw_rectangles.  That is, the
    backends no nothing about matplotlib.Artists

KNOWN BUGS

  * vertical text problem in PS to be fixed

This was a pretty comprehensive change so I recommend syncing your CVS
tree.

Todd, I needed Numeric.Matrix to do the linear algebra for the
rotations in the text module text.  Is there a numarray equivalent
that we can expose in numerix?

Paul, I committed these changes after synching with your new font
caching and there doesn't appear to be any problem; miraculously CVS
seems to be working pretty well.  I did some additional caching of AFM
instances in backend_ps.  You might want to rerun your ps profile
script and see if the numbers improve further still.

JDH