matplotlib-users Mailing List for matplotlib

>
> "Alexander Michael" <[EMAIL PROTECTED]> writes:
>
> > I would like to create a plot axis with major tick labels centered
> > *between* major tick markers instead below tick markers.
>
> Take a look at
>
> http://thread.gmane.org/gmane.comp.python.matplotlib.general/5271
> http://thread.gmane.org/gmane.comp.python.matplotlib.general/5296
> http://www.scipy.org/Cookbook/Matplotlib/Transformations
>
> --
> Jouni
>
>
>From your references, I have been mostly able to figure out how to do it.
Thank you.
So far, I have:

# create transformation with x in data coords and y in axes coordinates
transLabels = matplotlib.transforms.blend_xy_sep_transform(
    ax.transData, ax.transAxes)

# get major locator and usurp major formatter for custom positioning
major_locator = ax.xaxis.get_major_locator()
major_formatter = ax.xaxis.get_major_formatter()
ax.xaxis.set_major_formatter(matplotlib.ticker.NullFormatter())

# create custom text labels centered between major tick marks
major_locs = major_locator()
for i in range(1,len(major_locs)):
    x_last,x = major_locs[i-1],major_locs[i]
    ax.text(0.5*(x+x_last), -0.04, major_formatter(x, i),
        transform=transLabels, horizontalalignment='center')

When "zooming around" an interactive plot, however, my custom labels get
pushed
off into the margins. I'm guessing I need to put them in a clip box somehow.
Any hints?

Thanks!
Alex

Thanks for the detailed reply. I was just wondering whether I was  
missing something obvious and
that doesn't seem to be the case.

Cheers

Daniel Wheeler

On Aug 2, 2006, at 2:15 PM, John Hunter wrote:

>>>>>> "Daniel" == Daniel Wheeler <dan...@ni...> writes:
>
>     Daniel>    It seems that resetting the axes limits every time data
>     Daniel> needs to be redisplayed is rather inefficient.  A script
>     Daniel> is included with this mail that tests the efficiency of
>     Daniel> resizing the y axis.  The script has two loops, in the
>     Daniel> first loop pylab.ylim() is continuously called with the
>     Daniel> changing size of the domain, in the second loop
>     Daniel> pylab.ylim() is not called inside the loop. The first loop
>     Daniel> takes roughly twice as long to perform.  Is this an
>     Daniel> unavoidable cost for resizing the y axis or is there
>     Daniel> another way to resize the axis that is less costly than
>     Daniel> using ylim()?
>
> The cost from the tick layout and formatting -- this could be made
> more efficient but that is where the cost is currently.  For every
> tick label, matplotlib does a layout assuming you may have passed a
> rotated multiline string.  Special casing the no newline, non-rotated
> case is probably where the biggest win would come from.  It is
> a good project for someone to tackle, but the text layout code is kind
> of hairy because it deals with so many cases: mathtext, usetex,
> rotated strings, multiline strings, top/bottom left/right alignment,
> and so on.
>
> A complete refactoring of ticks to treat them as a single
> collection-like object rather than a bunch of independent objects
> would also help a lot here.
>
> JDH


Daniel Wheeler

>>>>> "Daniel" == Daniel Wheeler <dan...@ni...> writes:

    Daniel>    It seems that resetting the axes limits every time data
    Daniel> needs to be redisplayed is rather inefficient.  A script
    Daniel> is included with this mail that tests the efficiency of
    Daniel> resizing the y axis.  The script has two loops, in the
    Daniel> first loop pylab.ylim() is continuously called with the
    Daniel> changing size of the domain, in the second loop
    Daniel> pylab.ylim() is not called inside the loop. The first loop
    Daniel> takes roughly twice as long to perform.  Is this an
    Daniel> unavoidable cost for resizing the y axis or is there
    Daniel> another way to resize the axis that is less costly than
    Daniel> using ylim()?

The cost from the tick layout and formatting -- this could be made
more efficient but that is where the cost is currently.  For every
tick label, matplotlib does a layout assuming you may have passed a
rotated multiline string.  Special casing the no newline, non-rotated
case is probably where the biggest win would come from.  It is
a good project for someone to tackle, but the text layout code is kind
of hairy because it deals with so many cases: mathtext, usetex,
rotated strings, multiline strings, top/bottom left/right alignment,
and so on.

A complete refactoring of ticks to treat them as a single
collection-like object rather than a bunch of independent objects
would also help a lot here.

JDH

It seems that resetting the axes limits every time data needs to be =20
redisplayed is rather inefficient.

A script is included with this mail that tests the efficiency of =20
resizing the y axis.
The script has two loops, in the first loop pylab.ylim() is =20
continuously called with the changing
size of the domain, in the second loop pylab.ylim() is not called =20
inside the loop. The first loop takes roughly
twice as long to perform.

Is this an unavoidable cost for resizing the y axis or is there =20
another way to resize the axis that is less costly
than using ylim()?

=EF=BF=BC
Cheers

Daniel Wheeler