matplotlib-users Mailing List for matplotlib

On Tuesday 01 August 2006 08:52, John Hunter wrote:
> >>>>> "Jouni" == Jouni K Seppanen <jk...@ik...> writes:
>
>     Jouni> The draw_lines method in the PS backend divides the line
>     Jouni> into subsequences of at most 50 points, and calls the
>     Jouni> "stroke" operator for each subsequence, which in effect
>     Jouni> resets the dash offset. Thus if 50 consecutive points fit
>     Jouni> within a dash, the line appears solid.
>
> 50 seems awfully small to me.  There are maximum length path
> limitations of some postscript interpreters which is why we batch
> these up.  Darren, could we get away with a step of 1000 here rather
> than 50?

Here are GGV's render times for a line containing 1e6 points:

division | time (s)
50		3
1000	9
100000	8
none	28

I bumped it up to 100,000 in svn 2644, which seems to have improved the dash 
problem.

Darren

>
>
> There is a nice little trick where you can make two axes share the
> same xaxis.  Then when you pan or zoom on one, the other is
> automagically changed to
>
> ax1 = subplot(211)
> ax2 = subplot(212, sharex=ax1)


But that's not retroactive, or is it ? i.e. if ax2 has a wider x range than
ax1, it won't show up.
f = figure(1)
s1 = subplot(211)
s1.plot([1,2,3], [1,2,3])
s2 = subplot(212, sharex = s1)
s2.plot([4,5,6], [1,2,3])


I came up with the following function to solve that problem. Is there a more
elegant solution?

def uniform_limits(axes, xrange = 'widest', yrange = 'widest'):
    """For all axes, sets xlim and ylim to the widest (shortest) range."""
    x = []
    y = []
    for ax in axes:
        x.append(ax.get_xlim())
        y.append(ax.get_ylim())
    x = vstack(asarray(x))
    y = vstack(asarray(y))
    if xrange == 'widest':
        xlims = x.min(0)[0], x.max(0)[1]
    elif xrange == 'shortest':
        xlims = x.max(0)[0], x.min(0)[1]
    if yrange == 'widest':
        ylims = y.min(0)[0], y.max(0)[1]
    elif yrange == 'shortest':
        ylims = y.max(0)[0], y.min(0)[1]
    setp(axes, 'xlim', xlims, 'ylim', ylims)


David

>>>>> "Jouni" == Jouni K Seppanen <jk...@ik...> writes:
    Jouni> The draw_lines method in the PS backend divides the line
    Jouni> into subsequences of at most 50 points, and calls the
    Jouni> "stroke" operator for each subsequence, which in effect
    Jouni> resets the dash offset. Thus if 50 consecutive points fit
    Jouni> within a dash, the line appears solid.

50 seems awfully small to me.  There are maximum length path
limitations of some postscript interpreters which is why we batch
these up.  Darren, could we get away with a step of 1000 here rather
than 50?

JDH

>>>>> "David" == David Huard <dav...@gm...> writes:

    David> Hi John, Thanks for taking the time to answer a badly
    David> formulated question. With your indications, I have been
    David> able to get an example working.

Great.

    David> s1.set_xlim(s2.get_xlim()) 

There is a nice little trick where you can make two axes share the
same xaxis.  Then when you pan or zoom on one, the other is
automagically changed to

ax1 = subplot(211)
ax2 = subplot(212, sharex=ax1)

Ditto for sharey.  A very useful trick!

JDH

Eric Emsellem <ems...@ob...> writes:

> But when saving it in a postscript the dashed line looks solid on most
> of the plot.
> This happens if there are too many points in the line:

The draw_lines method in the PS backend divides the line into
subsequences of at most 50 points, and calls the "stroke" operator for
each subsequence, which in effect resets the dash offset. Thus if 50
consecutive points fit within a dash, the line appears solid.

I suppose the division into subsequences solves some memory or speed
problem with PS interpreters, so it should be retained. Then the
solution would be to compute the length X of each subsequence and do
something like "currentdash pop X setdash" after the "stroke".

-- 
Jouni

Hi,
I just produced a plot with a curve dashed line:

when saving it into a png file it works fine.
But when saving it in a postscript the dashed line looks solid on most
of the plot.
This happens if there are too many points in the line:

x = arange(0,1.,0.0001)
y = sqrt(x)
plot(x,y,'k--')
## Png file is ok
savefig("toto.png")
## Eps file is NOT ok
savefig("toto.eps")

Any cure to that behaviour?

Thanks!!!
Eric

"Alexander Michael" <lxa...@gm...> 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

Hi John,

Thanks for taking the time to answer a badly formulated question. With your
indications, I have been able to get an example working.

The point was that I had a function with a number of arguments that returned
a subplot(111) instance. Inside this function there are thousands of  calls
to plot, there are labels and a title. I called the function  from my main
script, called savefig and stored the figure. Now I want to compare two such
figures side by side, and ideally tweak the axes so they are identical.

Here is what I came up with your help:

def make_complicated_graph(x, sub = None):
    s = sub or subplot(111)
    s.plot(x)
    s.set_title('test12')
    s.set_xlabel('T')
    s.set_ylabel('Y')
    s.scatter([3,4], [5,2], s= 5, c='r')
    if sub is None:
        return s


fig = figure(1)
s1 = subplot(2,1,1)
s2 = subplot(2,1,2)
make_complicated_graph(arange(5), sub = s1)
make_complicated_graph(arange(10), sub = s2)
s1.set_xlim(s2.get_xlim())
show()


Thanks again for your help.

David